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Isoroku Yamamoto

Isoroku Yamamoto (山本 五十六) was a Marshal Admiral of the Imperial Japanese Navy (IJN) and the commander-in-chief of the Combined Fleet during World War II. Yamamoto held several important posts in the Imperial Navy, and undertook many of its changes and reorganizations, especially its development of naval aviation. He was the commander-in-chief during the early years of the Pacific War and oversaw major engagements including the attack on Pearl Harbor and the Battle of Midway. Yamamoto was killed in April 1943 after American code breakers identified his flight plans, enabling the United States Army Air Forces to shoot down his aircraft.

Family background
Yamamoto was born as Isoroku Takano (高野 五十六) in Nagaoka, Niigata. His father, Sadayoshi Takano (高野 貞吉), had been an intermediate-rank samurai of the Nagaoka Domain. "Isoroku" is a Japanese term meaning "56"; the name referred to his father's age at Isoroku's birth.

In 1916, Isoroku was adopted into the Yamamoto family (another family of former Nagaoka samurai) and took the Yamamoto name. It was a common practice for samurai families lacking sons to adopt suitable young men in this fashion to carry on the family name, the rank and the income that went with it. Isoroku married Reiko Mihashi in 1918; they had two sons and two daughters.

Early career
Yamamoto graduated from the Imperial Japanese Naval Academy in 1904, ranking 11th in his class. He then subsequently served on the armored cruiser JAPANESE CRUISER Nisshin during the Russo-Japanese War. He was wounded at the Battle of Tsushima, losing his index and middle fingers on his left hand, as the cruiser was hit repeatedly by the Russian battle line. He returned to the Naval Staff College in 1914, emerging as a lieutenant commander in 1916. In December 1919, he was promoted to commander.

1920s and 1930s
Yamamoto was part of the Japanese Navy establishment, who were rivals of the more aggressive Army establishment, especially the officers of the Kwantung Army. He promoted a policy of a strong fleet to project force through gunboat diplomacy, rather than a fleet used primarily for the transport of invasion land forces, as some of his political opponents in the Army wanted. This stance led him to oppose the invasion of China. He also opposed war against the United States, partly because of his studies at Harvard University (1919–1921) and his two postings as a naval attaché in Washington, D.C., where he learned to speak fluent English. Yamamoto traveled extensively in the United States during his tour of duty there, where he studied American customs and business practices.

He was promoted to captain in 1923. On February 13, 1924, Captain Yamamoto was part of the Japanese delegation visiting the United States Naval War College. Later that year, he changed his specialty from gunnery to naval aviation. His first command was the cruiser JAPANESE CRUISER Isuzu in 1928, followed by the aircraft carrier JAPANESE AIRCRAFT CARRIER Akagi.

He participated in the London Naval Conference 1930 as a rear admiral and the London Naval Conference 1935 as a vice admiral, as the growing military influence on the government at the time deemed that a career military specialist needed to accompany the diplomats to the arms limitations talks. Yamamoto was a strong proponent of naval aviation and served as head of the Aeronautics Department, before accepting a post as commander of the First Carrier Division. Yamamoto opposed the Japanese invasion of northeast China in 1931, the subsequent full-scale land war with China in 1937, and the Tripartite Pact with Nazi Germany and Fascist Italy in 1940. As Deputy Navy Minister, he apologized to United States Ambassador Joseph C. Grew for the bombing of the gunboat USS Panay in December 1937. These issues made him a target of assassination threats by pro-war militarists.

Throughout 1938, many young army and naval officers began to speak publicly against Yamamoto and certain other Japanese admirals, such as Mitsumasa Yonai and Shigeyoshi Inoue, for their strong opposition to a tripartite pact with Nazi Germany and Fascist Italy, which the admirals saw as inimical to "Japan's natural interests". Yamamoto received a steady stream of hate mail and death threats from Japanese nationalists. His reaction to the prospect of death by assassination was passive and accepting. The admiral wrote: "To die for Emperor and Nation is the highest hope of a military man. After a brave hard fight the blossoms are scattered on the fighting field. But if a person wants to take a life instead, still the fighting man will go to eternity for Emperor and country. One man's life or death is a matter of no importance. All that matters is the Empire. As Confucius said, 'They may crush cinnabar, yet they do not take away its color; one may burn a fragrant herb, yet it will not destroy the scent.' They may destroy my body, yet they will not take away my will."

The Japanese Army, annoyed at Yamamoto's unflinching opposition to a Rome-Berlin-Tokyo treaty, dispatched military police to "guard" him, a ruse by the Army to keep an eye on him. He was later reassigned from the naval ministry to sea as the commander-in-chief of the Combined Fleet on August 30, 1939. This was done as one of the last acts of acting Navy Minister Mitsumasa Yonai, under Baron Hiranuma Kiichirō's short-lived administration. It was done partly to make it harder for assassins to target Yamamoto. Yonai was certain that if Yamamoto remained ashore, he would be killed before the year [1939] ended.

1940–1941
Yamamoto was promoted to admiral on November 15, 1940. This was in spite of the fact that when Hideki Tojo was appointed Prime Minister on October 18, 1941, many political observers thought that Yamamoto's career was essentially over. Tojo had been Yamamoto's old opponent from the time when the latter served as Japan's deputy naval minister and Tojo was the prime mover behind Japan's takeover of Manchuria. It was believed that Yamamoto would be appointed to command the Yokosuka Naval Base, "a nice safe demotion with a big house and no power at all". However, after a brief stint in the post, a new Japanese cabinet was announced, and Yamamoto found himself returned to his position of power despite his open conflict with Tojo and other members of the Army's oligarchy who favored war with the European powers and the United States.

Two of the main reasons for Yamamoto's political survival were his immense popularity within the fleet, where he commanded the respect of his men and officers, and his close relations with the imperial family. He also had the acceptance of Japan's naval hierarchy: "There was no officer more competent to lead the Combined Fleet to victory than Admiral Yamamoto. His daring plan for the Pearl Harbor attack had passed through the crucible of the Japanese naval establishment, and after many expressed misgivings, his fellow admirals had realized that Yamamoto spoke no more than the truth when he said that Japan's hope for victory in this [upcoming] war was limited by time and oil. Every sensible officer of the navy was well aware of the perennial oil problems. Also, it had to be recognized that if the enemy could seriously disturb Japanese merchant shipping, then the fleet would be endangered even more."

Consequently, Yamamoto stayed in his post. With Tojo now in charge of Japan's highest political office, it became clear the Army would lead the Navy into a war about which Yamamoto had serious reservations. He wrote to an ultranationalist: "Should hostilities once break out between Japan and the United States, it would not be enough that we take Guam and the Philippines, nor even Hawaii and San Francisco. To make victory certain, we would have to march into Washington and dictate the terms of peace in the White House. I wonder if our politicians [who speak so lightly of a Japanese-American war] have confidence as to the final outcome and are prepared to make the necessary sacrifices."

This quote was spread by the militarists, minus the last sentence, so it was interpreted in America as a boast that Japan would conquer the entire continental United States. The omitted sentence showed Yamamoto's counsel of caution towards a war that could cost Japan dearly. Nevertheless, Yamamoto accepted the reality of impending war and planned for a quick victory by destroying the United States Pacific Fleet at Pearl Harbor in a preventive strike, while simultaneously thrusting into the oil- and rubber-rich areas of Southeast Asia, especially the Dutch East Indies, Borneo, and Malaya. In naval matters, Yamamoto opposed the building of the battleships JAPANESE BATTLESHIP Yamato and JAPANESE BATTLESHIP Musashi as an unwise investment of resources.

Yamamoto was responsible for a number of innovations in Japanese naval aviation. Although remembered for his association with aircraft carriers, Yamamoto did more to influence the development of land-based naval aviation, particularly the Mitsubishi G3M and G4M medium bombers. His demand for great range and the ability to carry a torpedo was intended to conform to Japanese conceptions of bleeding the American fleet as it advanced across the Pacific. The planes did achieve long range, but long-range fighter escorts were not available. These planes were lightly constructed and when fully fueled, they were especially vulnerable to enemy fire. This earned the G4M the sardonic nickname the "flying cigarette lighter". Yamamoto would eventually die in one of these aircraft.

The range of the G3M and G4M contributed to a demand for great range in a fighter aircraft. This partly drove the requirements for the A6M Zero, which was as noteworthy for its range as for its maneuverability. Both qualities were again purchased at the expense of light construction and flammability that later contributed to the A6M's high casualty rates as the war progressed.

As Japan moved toward war during 1940, Yamamoto gradually moved toward strategic as well as tactical innovation, again with mixed results. Prompted by talented young officers such as Lieutenant Commander Minoru Genda, Yamamoto approved the reorganization of Japanese carrier forces into the First Air Fleet, a consolidated striking force that gathered Japan's six largest carriers into one unit. This innovation gave great striking capacity, but also concentrated the vulnerable carriers into a compact target. Yamamoto also oversaw the organization of a similar large land-based organization in the 11th Air Fleet, which would later use the G3M and G4M to neutralize American air forces in the Philippines and sink the British Force Z. In January 1941, Yamamoto went even further and proposed a radical revision of Japanese naval strategy. For two decades, in keeping with the doctrine of Captain Alfred T. Mahan, the Naval General Staff had planned in terms of Japanese light surface forces, submarines, and land-based air units whittling down the American fleet as it advanced across the Pacific until the Japanese Navy engaged it in a climactic Kantai Kessen ("decisive battle") in the northern Philippine Sea (between the Ryukyu Islands and the Marianas), with battleships fighting in traditional battle lines.

Correctly pointing out this plan had never worked even in Japanese war games, and painfully aware of American strategic advantages in military production capacity, Yamamoto proposed instead to seek parity with the Americans by first reducing their forces with a preventive strike, then following up with a "decisive battle" fought offensively, rather than defensively. Yamamoto hoped, but probably did not believe, that if the Americans could be dealt terrific blows early in the war, they might be willing to negotiate an end to the conflict. The Naval General Staff proved reluctant to go along, and Yamamoto was eventually driven to capitalize on his popularity in the fleet by threatening to resign to get his way. Admiral Osami Nagano and the Naval General Staff eventually caved in to this pressure, but only insofar as approving the attack on Pearl Harbor. In January 1941 Yamamoto began developing a plan to attack the American base in Pearl Harbor, Hawaii. which the Japanese continued to refine during the next months. On November 5, 1941, Yamamoto in his "Top Secret Operation Order no. 1" issued to the Combined Fleet, the Empire of Japan must drive out Britain and America from Greater East Asia and hasten the settlement of China, whereas, in the event that Britain and America were driven out from the Philippines and Dutch East Indies, an independent, self-supporting economic entity will be firmly established—mirroring the principle of the Greater East Asia Co-Prosperity Sphere in another personification.

Two days later, he set the date for the intended surprise attack in Pearl Harbor and that would be on December 7 for one simple reason: it was a Sunday, the day that American military personnel would be least alert to an attack.

The First Air Fleet commenced preparations for the Pearl Harbor raid, solving a number of technical problems along the way, including how to launch torpedoes in the shallow waters of Pearl Harbor and how to craft armor-piercing bombs by machining down battleship gun projectiles.

Attack on Pearl Harbor
Although the United States and Japan were officially at peace, the First Air Fleet of six carriers attacked on December 7, 1941, launching 353 aircraft against Pearl Harbor and other locations within Honolulu in two waves. The attack was a success according to the parameters of the mission, which sought to sink at least four American battleships and prevent the United States from interfering in Japan's southward advance for at least six months. Three American aircraft carriers were also considered a choice target, but these were at sea at the time.

In the end, four American battleships were sunk, four were damaged, and eleven other cruisers, destroyers, and auxiliaries were sunk or seriously damaged, 188 American aircraft were destroyed and 159 others damaged, and 2,403 people were killed and 1,178 others wounded. The Japanese lost 64 servicemen and only 29 aircraft, with 74 others damaged by anti-aircraft fire from the ground. The damaged aircraft were disproportionately dive and torpedo bombers, seriously reducing the ability to exploit the first two waves' success, so the commander of the First Air Fleet, Naval Vice Admiral Chuichi Nagumo, withdrew. Yamamoto later lamented Nagumo's failure to seize the initiative to seek out and destroy the American carriers or further bombard various strategically important facilities on Oahu.

Nagumo had absolutely no idea where the American carriers were, and remaining on station while his forces looked for them ran the risk of his own forces being found first and attacked while his aircraft were absent searching. In any case, insufficient daylight remained after recovering the aircraft from the first two waves for the carriers to launch and recover a third before dark, and Nagumo's escorting destroyers lacked the fuel capacity to loiter long. Much has been made of Yamamoto's hindsight, but in keeping with Japanese military tradition to not criticize the commander on the spot, he did not punish Nagumo for his withdrawal. On the strategic, moral, and political level, the attack was a disaster for Japan, rousing Americans' thirst for revenge due to what is famously called a "sneak attack". The shock of the attack, coming in an unexpected place with devastating results and without a declaration of war, galvanized the American public's determination to avenge the attack. When asked by Prime Minister Fumimaro Konoe in mid-1941 about the outcome of a possible war with the United States, Yamamoto made a well-known and prophetic statement: If ordered to fight, he said, "I shall run wild considerably for the first six months or a year, but I have utterly no confidence for the second and third years." His prediction would be validated, as Japan easily conquered territories and islands in Asia and the Pacific for the first six months of the war, before suffering a major defeat at the Battle of Midway on June 4–7, 1942, which ultimately tilted the balance of power in the Pacific toward the United States.

December 1941 – May 1942

With the American fleet largely neutralized at Pearl Harbor, Yamamoto's Combined Fleet turned to the task of executing the larger Japanese war plan devised by the Imperial Japanese Army and Navy General Staff. The First Air Fleet made a circuit of the Pacific, striking American, Australian, Dutch, and British installations from Wake Island to Australia to Ceylon in the Indian Ocean. The 11th Air Fleet caught the United States Fifth Air Force on the ground in the Philippines hours after Pearl Harbor, and then sank the British Force Z's battleship HMS Prince of Wales (53) and battlecruiser HMS Repulse (1916) at sea.

Under Yamamoto's able subordinates, Vice Admirals Jisaburō Ozawa, Nobutake Kondō, and Ibō Takahashi, the Japanese swept the inadequate remaining American, British, Dutch and Australian naval assets from the Dutch East Indies in a series of amphibious landings and surface naval battles culminating in the Battle of the Java Sea on February 27, 1942. Along with the occupation of the Dutch East Indies came the fall of Singapore on February 15, and the eventual reduction of the remaining American-Filipino defensive positions in the Philippines on the Bataan peninsula on April 9 and Corregidor Island on May 6. The Japanese had secured their oil- and rubber-rich "southern resources area".

By late March, having achieved their initial aims with surprising speed and little loss, albeit against enemies ill-prepared to resist them, the Japanese paused to consider their next moves. Yamamoto and a few Japanese military leaders and officials waited, hoping that the United States or Great Britain would negotiate an armistice or a peace treaty to end the war. But when the British, as well as the Americans, expressed no interest in negotiating, Japanese thoughts turned to securing their newly seized territory and acquiring more with an eye to driving one or more of their enemies out of the war.

Competing plans were developed at this stage, including thrusts to the west against British India, south against Australia, and east against the United States. Yamamoto was involved in this debate, supporting different plans at different times with varying degrees of enthusiasm and for varying purposes, including "horse-trading" for support of his own objectives.

Plans included ideas as ambitious as invading India or Australia, or seizing Hawaii. These grandiose ventures were inevitably set aside, as the Army could not spare enough troops from China for the first two, which would require a minimum of 250,000 men, nor shipping to support the latter two (transports were allocated separately to the Navy and Army, and jealously guarded). Instead, the Imperial General Staff supported an army thrust into Burma in hopes of linking up with Indian nationalists revolting against British rule, and attacks in New Guinea and the Solomon Islands designed to imperil Australia's lines of communication with the United States. Yamamoto argued for a decisive offensive strike in the east to finish off the American fleet, but the more conservative Naval General Staff officers were unwilling to risk it.

On April 18, in the midst of these debates, the Doolittle Raid struck Tokyo and surrounding areas, demonstrating the threat posed by American aircraft carriers, and giving Yamamoto an event he could exploit to get his way, and further debate over military strategy came to a quick end. The Naval General Staff agreed to Yamamoto's Midway Island (MI) Operation, subsequent to the first phase of the operations against Australia's link with America, and concurrent with its plan to invade the Aleutian Islands.

Yamamoto rushed planning for the Midway and Aleutians missions, while dispatching a force under Vice Admiral Takeo Takagi, including the Fifth Carrier Division (the large new carriers JAPANESE AIRCRAFT CARRIER Shōkaku and JAPANESE AIRCRAFT CARRIER Zuikaku), to support the effort to seize the islands of Tulagi and Guadalcanal for seaplane and airplane bases, and the town of Port Moresby on Papua New Guinea's south coast facing Australia.

The Port Moresby (MO) Operation proved an unwelcome setback. Although Tulagi and Guadalcanal were taken, the Port Moresby invasion fleet was compelled to turn back when Takagi clashed with an American carrier task force in the Battle of the Coral Sea in early May. Although the Japanese sank the carrier USS Lexington (CV-2) and damaged the USS Yorktown (CV-5), the Americans damaged the carrier Shōkaku so badly that she required dockyard repairs, and the Japanese lost the light carrier JAPANESE AIRCRAFT CARRIER Shoho. Just as importantly, Japanese operational mishaps and American fighters and anti-aircraft fire devastated the dive bomber and torpedo plane formations of both Shōkakus and Zuikakus air groups. These losses sidelined Zuikaku while she awaited replacement aircraft and aircrews, and saw to tactical integration and training. These two ships would be sorely missed a month later at Midway.

Battle of Midway, June 1942
Yamamoto's plan for Midway Island was an extension of his efforts to knock the American Pacific Fleet out of action long enough for Japan to fortify its defensive perimeter in the Pacific island chains. Yamamoto felt it necessary to seek an early, offensive decisive battle.

This plan was long believed to have been to draw American attention—and possibly carrier forces—north from Pearl Harbor by sending his Fifth Fleet (one carrier, one light carrier, four battleships, eight cruisers, 25 destroyers, and four transports) against the Aleutians, raiding Dutch Harbor on Unalaska Island and invading the more distant islands of Kiska and Attu.

While Fifth Fleet attacked the Aleutians, First Mobile Force (four carriers, two battleships, three cruisers, and 12 destroyers) would attack Midway and destroy its air force. Once this was neutralized, Second Fleet (one light carrier, two battleships, 10 cruisers, 21 destroyers, and 11 transports) would land 5,000 troops to seize the atoll from the United States Marines.

The seizure of Midway was expected to draw the American carriers west into a trap where the First Mobile Force would engage and destroy them. Afterwards, First Fleet (one light carrier, three battleships, one light cruiser and nine destroyers), in conjunction with elements of Second Fleet, would mop up remaining US surface forces and complete the destruction of the American Pacific Fleet.

To guard against failure, Yamamoto initiated two security measures. The first was an aerial reconnaissance mission (Operation K) over Pearl Harbor to ascertain if the American carriers were there. The second was a picket line of submarines to detect the movement of enemy carriers toward Midway in time for First Mobile Force, First Fleet, and Second Fleet to combine against it. In the event, the first measure was aborted and the second delayed until after the American carriers had already sortied.

The plan was a compromise and hastily prepared, apparently so it could be launched in time for the anniversary of the Battle of Tsushima, but appeared well thought out, well organized, and finely timed when viewed from a Japanese viewpoint. Against four fleet carriers, two light carriers, seven battleships, 14 cruisers and 42 destroyers likely to be in the area of the main battle, the United States could field only three carriers, eight cruisers, and 15 destroyers. The disparity appeared crushing. Only in numbers of carrier decks, available aircraft, and submarines was there near parity between the two sides. Despite various mishaps developed in the execution, it appeared that—barring something unforeseen—Yamamoto held all the cards.

Unknown to Yamamoto, the Americans had learned of Japanese plans thanks to the code breaking of Japanese naval code D (known to the US as JN-25). As a result, Admiral Chester Nimitz, the Pacific Fleet commander, was able to place his outnumbered forces in a position to conduct their own ambush. By Nimitz's calculation, his three available carrier decks, plus Midway, gave him rough parity with Nagumo's First Mobile Force.

Following a nuisance raid by Japanese flying boats in May, Nimitz dispatched a minesweeper to guard the intended refueling point for Operation K near French Frigate Shoals, causing the reconnaissance mission to be aborted and leaving Yamamoto ignorant of whether the Pacific Fleet carriers were still at Pearl Harbor. It remains unclear why Yamamoto permitted the earlier attack, and why his submarines did not sortie sooner, as reconnaissance was essential to success at Midway. Nimitz also dispatched his carriers toward Midway early, and they passed the Japanese submarines en route to their picket line positions. Nimitz's carriers positioned themselves to ambush the Kidō Butai (striking force) when it struck Midway. A token cruiser and destroyer force was sent toward the Aleutians, but otherwise Nimitz ignored them. On June 4, 1942, days before Yamamoto expected them to interfere in the Midway operation, American carrier-based aircraft destroyed the four carriers of the Kidō Butai, catching the Japanese carriers at especially vulnerable times.

With his air power destroyed and his forces not yet concentrated for a fleet battle, Yamamoto maneuvered his remaining forces, still strong on paper, to trap the American forces. He was unable to do so because his initial dispositions had placed his surface combatants too far from Midway, and because Admiral Raymond Spruance prudently withdrew to the east to further defend Midway Island, believing (based on a mistaken submarine report) the Japanese still intended to invade. Not knowing several battleships, including the powerful JAPANESE BATTLESHIP Yamato, were in the Japanese order of battle, he did not comprehend the severe risk of a night surface battle, in which his carriers and cruisers would be at a disadvantage. However, his move to the east avoided that possibility. Correctly perceiving he had lost and could not bring surface forces into action, Yamamoto withdrew. The defeat marked the high tide of Japanese expansion.

Yamamoto's plan has been the subject of much criticism. Some historians state it violated the principle of concentration of force and was overly complex. Others point to similarly complex Allied operations, such as Operation MB8, that were successful, and note the extent to which the American intelligence coup derailed the operation before it began. Had Yamamoto's dispositions not denied Nagumo adequate pre-attack reconnaissance assets, both the American cryptanalytic success and the unexpected appearance of the American carriers would have been irrelevant.

Actions after Midway
The Battle of Midway checked Japanese momentum, but the Japanese Navy was still a powerful force, capable of regaining the initiative. It planned to resume the thrust with Operation FS, aimed at eventually taking Fiji and Samoa to cut the American lifeline to Australia.

Yamamoto remained as commander-in-chief, retained at least partly to avoid diminishing the morale of the Combined Fleet. However, he had lost face as a result of the Midway defeat, and the Naval General Staff were disinclined to indulge in further gambles. This reduced Yamamoto to pursuing the classic defensive "decisive battle strategy" he had attempted to avoid.

Yamamoto committed Combined Fleet units to a series of small attrition actions across the south and central Pacific that stung the Americans, but in return suffered losses he could ill afford. Three major efforts to beat the Americans moving on Guadalcanal precipitated a pair of carrier battles that Yamamoto commanded personally: the Battles of the Eastern Solomons and Santa Cruz Islands in September and October, respectively, and finally a pair of wild surface engagements in November, all timed to coincide with Japanese Army pushes. The effort was wasted when the Army could not hold up its end of the operation. Yamamoto's naval forces won a few victories and inflicted considerable losses and damage to the American fleet in several battles around Guadalcanal which included the Battles of Savo Island, Cape Esperance, and Tassafaronga, but he could never draw the United States into a decisive fleet action. As a result, Japanese naval strength declined.

Death
To boost morale following the defeat at Guadalcanal, Yamamoto decided to make an inspection tour throughout the South Pacific. It was during this tour that U.S. officials commenced an operation to kill him. On April 14, 1943, the United States naval intelligence effort, codenamed "Magic", intercepted and decrypted a message containing specifics of Yamamoto's tour, including arrival and departure times and locations, as well as the number and types of aircraft that would transport and accompany him on the journey. Yamamoto, the itinerary revealed, would be flying from Rabaul to Balalae Airfield, on an island near Bougainville in the Solomon Islands, on the morning of April 18, 1943.

President Franklin D. Roosevelt may have authorized Secretary of the Navy Frank Knox to "get Yamamoto", but no official record of such an order exists, and sources disagree whether he did so. Knox essentially let Admiral Chester W. Nimitz make the decision. Nimitz first consulted Admiral William Halsey Jr., Commander, South Pacific, and then authorized the mission on April 17 to intercept and shoot down Yamamoto's flight en route. A squadron of United States Army Air Forces Lockheed P-38 Lightning aircraft were assigned the task as only they possessed sufficient range. Select pilots from three units were informed that they were intercepting an "important high officer", with no specific name given.

On the morning of April 18, despite urging by local commanders to cancel the trip for fear of ambush, Yamamoto's two Mitsubishi G4M bombers, used as fast transport aircraft without bombs, left Rabaul as scheduled for the 315 mi trip. Sixteen P-38s intercepted the flight over Bougainville, and a dogfight ensued between them and the six escorting Mitsubishi A6M Zeroes. First Lieutenant Rex T. Barber engaged the first of the two Japanese transports, which turned out to be T1-323, the one Yamamoto was travelling in. He fired on the aircraft until it began to spew smoke from its left engine. Barber turned away to attack the other transport as Yamamoto's aircraft crashed into the jungle.

Yamamoto's body, along with the crash site, was found the next day in the jungle of the island of Bougainville by a Japanese search-and-rescue party, led by army engineer Lieutenant Tsuyoshi Hamasuna. According to Hamasuna, Yamamoto had been thrown clear of the plane's wreckage, his white-gloved hand grasping the hilt of his katana, still upright in his seat under a tree. Hamasuna said Yamamoto was instantly recognizable, head dipped down as if deep in thought. A post-mortem disclosed that Yamamoto had received two .50-caliber bullet wounds, one to the back of his left shoulder and another to the left side of his lower jaw that exited above his right eye. The Japanese navy doctor examining the body determined that the head wound had killed Yamamoto. The more violent details of Yamamoto's death were hidden from the Japanese public. The medical report was changed "on orders from above", according to biographer Hiroyuki Agawa.

Yamamoto's death was a major blow to Japanese military morale. His staff cremated his remains at Buin, Papua New Guinea, and his ashes were returned to Tokyo aboard the battleship JAPANESE BATTLESHIP Musashi, his last flagship. He was given a full state funeral on June 5, 1943, where he received, posthumously, the title of Marshal Admiral and was awarded the Order of the Chrysanthemum (1st Class). He was also awarded Nazi Germany's Knight's Cross of the Iron Cross with Oak Leaves and Swords. Some of his ashes were buried in the public Tama Cemetery, Tokyo (多摩霊園) and the remainder at his ancestral burial grounds at the temple of Chuko-ji in Nagaoka City. He was succeeded as commander-in-chief of the Combined Fleet by Admiral Mineichi Koga.

Personal life
Yamamoto practiced calligraphy. He and his wife, Reiko, had four children: two sons and two daughters. Yamamoto was an avid gambler, enjoying Go, shogi, billiards, bridge, mahjong, poker, and other games that tested his wits and sharpened his mind. He frequently made jokes about moving to Monaco and starting his own casino.

He enjoyed the company of geisha, and his wife Reiko revealed to the Japanese public in 1954 that Yamamoto was closer to his favorite geisha Kawai Chiyoko than to her, which stirred some controversy. His funeral procession passed by Kawai's quarters on the way to the cemetery. Yamamoto was close friends with Teikichi Hori, a Navy admiral and Yamamoto's classmate from the Imperial Japanese Naval Academy who was purged from the Navy for supporting the Washington Naval Treaty. Before and during the war Yamamoto frequently corresponded with Hori, these personal letters would become the subject of the NHK documentary The Truth of Yamamoto.

The claim that Yamamoto was a Catholic is likely due to confusion with retired Admiral Shinjiro Stefano Yamamoto, who was a decade older than Isoroku, and died in 1942.

Decorations

 * Grand Cordon of the Order of the Chrysanthemum (posthumous appointment, 18 April 1943)
 * Grand Cordon of the Order of the Rising Sun (29 April 1940; Fourth Class: 1 November 1920)
 * Grand Cordon of the Order of the Sacred Treasure (23 March 1939; Second Class: 31 October 1931; Fifth Class: 27 November 1911)
 * Order of the Golden Kite (1st class: 18 April 1943 (posthumous); Second Class: 4 April 1942)
 * Grand Cross of the Order of the German Eagle (Nazi Germany, 9 February 1940)
 * Knight's Cross of the Iron Cross with Oak Leaves and Swords (Nazi Germany, 27 May 1943 (posthumous))

Dates of rank

 * Midshipman – November 14, 1904
 * Ensign – August 31, 1905
 * Sublieutenant – September 28, 1907
 * Lieutenant – October 11, 1909
 * Lieutenant Commander – December 13, 1915
 * Commander – December 1, 1919
 * Captain – December 1, 1923
 * Rear Admiral – November 30, 1929
 * Vice Admiral – November 15, 1934
 * Admiral – November 15, 1940
 * Marshal-Admiral – April 18, 1943 (posthumous)

In film and fiction
Yamamoto was portrayed by Denjirō Ōkōchi in Toho's 1953 film Eagle of the Pacific.

The 1960 film The Gallant Hours depicts the battle of wits between Vice-Admiral William Halsey, Jr. and Yamamoto from the start of the Guadalcanal Campaign in August 1942 to Yamamoto's death in April 1943. The film, however, portrays Yamamoto's death as occurring in November 1942, the day after the Naval Battle of Guadalcanal, and the P-38 aircraft that killed him as coming from Guadalcanal.

In 1960's Storm Over the Pacific from Toho Studios, Yamamoto is portrayed by Susumu Fujita.

In Daiei Studios's 1969 film Aa, kaigun (later released in the United States as Gateway to Glory), Yamamoto was portrayed by Shōgo Shimada.

Yamamoto is portrayed by Japanese actor Sō Yamamura in the 1970 movie Tora! Tora! Tora!; he states after the attack on Pearl Harbor: "I fear that all we have done is to awaken a sleeping giant and fill him with a terrible resolve."

Professional wrestler Harold Watanabe adopted the villainous Japanese gimmick of Tojo Yamamoto in reference to both Yamamoto and Hideki Tojo.

Award-winning Japanese actor Toshiro Mifune (star of The Seven Samurai) portrayed Yamamoto in three films:
 * Rengō Kantai Shirei Chōkan: Yamamoto Isoroku (1968, later released in Canada and the United States as Admiral Yamamoto),
 * Gekido no showashi 'Gunbatsu'  (1970, lit. "Turning Point of Showa History: The Militarists"), and
 * Midway (1976, where all of the Japanese scenes had English dialogue).

A fictionalized version of Yamamoto's death was portrayed in the Baa Baa Black Sheep episode "The Hawk Flies on Sunday", though only photos of Yamamoto were shown. In this episode, set much later in the war than in real life, the Black Sheep, a Marine Corsair squadron, joins an army squadron of P-51 Mustangs. The Marines intercepted fighter cover while the army shot down Yamamoto.

In Shūe Matsubayashi's 1981 film Rengō kantai (lit. "Combined Fleet", later released in the United States as The Imperial Navy), Yamamoto was portrayed by Keiju Kobayashi.

In the 1993 OVA series Konpeki no Kantai (lit. Deep Blue Fleet), right after his plane is shot down, Yamamoto suddenly wakes up as his younger self, Isoroku Takano, after the Battle of Tsushima in 1905. His memory from the original timeline intact, Yamamoto uses his knowledge of the future to help Japan become a stronger military power, eventually launching a coup d'état against Hideki Tōjō's government. In the subsequent Pacific War, Japan's technologically advanced navy decisively defeats the United States, and grants all of the former European and American colonies in Asia full independence. Yamamoto convinces Japan to join forces with the United States and Britain to defeat Nazi Germany. The series was criticized outside Japan as a whitewash of Imperial Japan's intentions towards its neighbors, and distancing itself from the wartime alliance with Nazi Germany.

In Neal Stephenson's 1999 book Cryptonomicon, Yamamoto's final moments are depicted, with him realizing that Japan's naval codes have been broken and that he must inform headquarters.

In the 2001 film Pearl Harbor, Yamamoto was portrayed by Japanese-born American actor Mako Iwamatsu. Like ''Tora! Tora! Tora!'', Yamamoto also says the sleeping giant quote.

In the 2004 anime series Zipang, Yamamoto, voiced by Bunmei Tobayama, works to develop the uneasy partnership with the crew of the JMSDF Mirai, which has been transported back through time to 1942.

In the Axis of Time trilogy by author John Birmingham, after a naval task force from the year 2021 is accidentally transported back through time to 1942, Yamamoto assumes a leadership role in the dramatic alteration of Japan's war strategy.

In The West Wing episode "We Killed Yamamoto", the Chairman of the Joint Chiefs of Staff uses the killing of Yamamoto to advocate for an assassination.

In Douglas Niles' 2007 book MacArthur's War: A Novel of the Invasion of Japan (written with Michael Dobson), which focuses on General Douglas MacArthur and an alternate history of the Pacific War (following a considerably different outcome of the Battle of Midway), Yamamoto is portrayed sympathetically, with much of the action in the Japanese government seen through his eyes, though he could not change the major decisions of Japan in World War II.

In Toei's 2011 war film Rengō Kantai Shirei Chōkan: Yamamoto Isoroku (Blu-Ray titles:- English "The Admiral"; German "Der Admiral"), Yamamoto was portrayed by Kōji Yakusho. The film portrays his career from Pearl Harbor to his death in Operation Vengeance.

In Robert Conroy's 2011 book Rising Sun, Yamamoto directs the IJN to launch a series of attacks on the American West Coast, in the hope the United States can be convinced to sue for peace and securing Japan's place as a world power; but cannot escape his lingering fear the war will ultimately doom Japan.

In the 2019 motion picture Midway, Yamamoto is portrayed by Etsushi Toyokawa. As with ''Tora! Tora! Tora! and Pearl Harbor'', the sleeping giant quote is included once again.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Isoroku Yamamoto


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Infrared spectroscopy

Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency, wavenumber or wavelength on the horizontal axis. Typical units of wavenumber used in IR spectra are reciprocal centimeters, with the symbol cm−1. Units of IR wavelength are commonly given in micrometers (formerly called "microns"), symbol μm, which are related to the wavenumber in a reciprocal way. A common laboratory instrument that uses this technique is a Fourier transform infrared (FTIR) spectrometer. Two-dimensional IR is also possible as discussed below.

The infrared portion of the electromagnetic spectrum is usually divided into three regions; the near-, mid- and far- infrared, named for their relation to the visible spectrum. The higher-energy near-IR, approximately 14,000–4,000 cm−1 (0.7–2.5 μm wavelength) can excite overtone or combination modes of molecular vibrations. The mid-infrared, approximately 4,000–400 cm−1 (2.5–25 μm) is generally used to study the fundamental vibrations and associated rotational–vibrational structure. The far-infrared, approximately 400–10 cm−1 (25–1,000 μm) has low energy and may be used for rotational spectroscopy and low frequency vibrations. The region from 2–130 cm−1, bordering the microwave region, is considered the terahertz region and may probe intermolecular vibrations. The names and classifications of these subregions are conventions, and are only loosely based on the relative molecular or electromagnetic properties.

Uses and applications
Infrared spectroscopy is a simple and reliable technique widely used in both organic and inorganic chemistry, in research and industry. In catalysis research it is a very useful tool to characterize the catalyst,  as well as to detect intermediates and products during the catalytic reaction. It is used in quality control, dynamic measurement, and monitoring applications such as the long-term unattended measurement of CO2 concentrations in greenhouses and growth chambers by infrared gas analyzers.

It is also used in forensic analysis in both criminal and civil cases, for example in identifying polymer degradation. It can be used in determining the blood alcohol content of a suspected drunk driver.

IR spectroscopy has been successfully used in analysis and identification of pigments in paintings and other art objects such as illuminated manuscripts.

Infrared spectroscopy is also useful in measuring the degree of polymerization in polymer manufacture. Changes in the character or quantity of a particular bond are assessed by measuring at a specific frequency over time. Modern research instruments can take infrared measurements across the range of interest as frequently as 32 times a second. This can be done whilst simultaneous measurements are made using other techniques. This makes the observations of chemical reactions and processes quicker and more accurate.

Infrared spectroscopy has also been successfully utilized in the field of semiconductor microelectronics: for example, infrared spectroscopy can be applied to semiconductors like silicon, gallium arsenide, gallium nitride, zinc selenide, amorphous silicon, silicon nitride, etc.

Another important application of infrared spectroscopy is in the food industry to measure the concentration of various compounds in different food products.

The instruments are now small, and can be transported, even for use in field trials.

Infrared spectroscopy is also used in gas leak detection devices such as the DP-IR and EyeCGAs. These devices detect hydrocarbon gas leaks in the transportation of natural gas and crude oil.

In February 2014, NASA announced a greatly upgraded database, based on IR spectroscopy, for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. According to scientists, more than 20% of the carbon in the universe may be associated with PAHs, possible starting materials for the formation of life. PAHs seem to have been formed shortly after the Big Bang, are widespread throughout the universe, and are associated with new stars and exoplanets.

Infrared spectroscopy is an important analysis method in the recycling process of household waste plastics, and a convenient stand-off method to sort plastic of different polymers (PET, HDPE, ...).

Other developments include a miniature IR-spectrometer that's linked to a cloud based database and suitable for personal everyday use, and NIR-spectroscopic chips that can be embedded in smartphones and various gadgets.

Infrared spectroscopy coupled with machine learning and artificial intelligence also has potential for rapid, accurate and non-invasive sensing of bacteria. The complex chemical composition of bacteria, including nucleic acids, proteins, carbohydrates and fatty acids, results in high-dimensional datasets where the essential features are effectively hidden under the total spectrum. Extraction of the essential features therefore requires advanced statistical methods such as machine learning and deep-neural networks. The potential of this technique for bacteria classification have been demonstrated for differentiation at the genus, species and serotype taxonomic levels, and it has also been shown promising for antimicrobial susceptibility testing,  which is important for many clinical settings where faster susceptibility testing would decrease unnecessary blind-treatment with broad-spectrum antibiotics. The main limitation of this technique for clinical applications is the high sensitivity to technical equipment and sample preparation techniques, which makes it difficult to construct large-scale databases. Attempts in this direction have however been made by Bruker with the IR Biotyper for food microbiology.

Theory
Infrared spectroscopy exploits the fact that molecules absorb frequencies that are characteristic of their structure. These absorptions occur at resonant frequencies, i.e. the frequency of the absorbed radiation matches the vibrational frequency. The energies are affected by the shape of the molecular potential energy surfaces, the masses of the atoms, and the associated vibronic coupling.

In particular, in the Born–Oppenheimer and harmonic approximations (i.e. when the molecular Hamiltonian corresponding to the electronic ground state can be approximated by a harmonic oscillator in the neighbourhood of the equilibrium molecular geometry), the resonant frequencies are associated with the normal modes of vibration corresponding to the molecular electronic ground state potential energy surface. Thus, it depends on both the nature of the bonds and the mass of the atoms that are involved. Using Schrödinger equation leads to the selection rule for the system undergoing vibrational changes:

$$\bigtriangleup v =\pm 1$$

The compression and extension of a bond may be likened to the behaviour of a spring, real molecules are hardly perfectly elastic in nature. If a bond between atoms is stretched, for instance, there comes a point at which the bond breaks, i.e., the molecule dissociates into atoms. Thus, real life molecules do not have exactly have perfect harmonic motion, they rather tend to deviate from it or, there exists anharmonicity in real life molecular vibrational motion. A purely empirical expression that fits the energy curve of a diatomic molecule undergoing anharmonic extension and compression to a good approximation s derived by P.M. Morse, and is called the Morse function. Using Schrödinger equation leads to the selection rule for the system undergoing vibrational changes :

$$\bigtriangleup v = \pm 1, \pm 2, \pm 3, \cdot\cdot\cdot$$

Number of vibrational modes
In order for a vibrational mode in a sample to be "IR active", it must be associated with changes in the molecular dipole moment. A permanent dipole is not necessary, as the rule requires only a change in dipole moment.

A molecule can vibrate in many ways, and each way is called a vibrational mode. For molecules with N number of atoms, geometrically linear molecules have 3N – 5 degrees of vibrational modes, whereas nonlinear molecules have 3N – 6 degrees of vibrational modes (also called vibrational degrees of freedom). As examples linear carbon dioxide (CO2) has 3 × 3 – 5 = 4, while non-linear water (H2O), has only 3 × 3 – 6 = 3.

Simple diatomic molecules have only one bond and only one vibrational band. If the molecule is symmetrical, e.g. N2, the band is not observed in the IR spectrum, but only in the Raman spectrum. Asymmetrical diatomic molecules, e.g. carbon monoxide (CO), absorb in the IR spectrum. More complex molecules have many bonds, and their vibrational spectra are correspondingly more complex, i.e. big molecules have many peaks in their IR spectra.

The atoms in a CH2X2 group, commonly found in organic compounds and where X can represent any other atom, can vibrate in nine different ways. Six of these vibrations involve only the CH2 portion: two stretching modes (ν): symmetric (νs) and antisymmetric (νas); and four bending modes: scissoring (δ), rocking (ρ), wagging (ω) and twisting (τ), as shown below. Structures that do not have the two additional X groups attached have fewer modes because some modes are defined by specific relationships to those other attached groups. For example, in water, the rocking, wagging, and twisting modes do not exist because these types of motions of the H atoms represent simple rotation of the whole molecule rather than vibrations within it. In case of more complex molecules, out-of-plane (γ) vibrational modes can be also present.

These figures do not represent the "recoil" of the C atoms, which, though necessarily present to balance the overall movements of the molecule, are much smaller than the movements of the lighter H atoms.

The simplest and most important or fundamental IR bands arise from the excitations of normal modes, the simplest distortions of the molecule, from the ground state with vibrational quantum number v = 0 to the first excited state with vibrational quantum number v = 1. In some cases, overtone bands are observed. An overtone band arises from the absorption of a photon leading to a direct transition from the ground state to the second excited vibrational state (v = 2). Such a band appears at approximately twice the energy of the fundamental band for the same normal mode. Some excitations, so-called combination modes, involve simultaneous excitation of more than one normal mode. The phenomenon of Fermi resonance can arise when two modes are similar in energy; Fermi resonance results in an unexpected shift in energy and intensity of the bands etc.

Practical IR spectroscopy
The infrared spectrum of a sample is recorded by passing a beam of infrared light through the sample. When the frequency of the IR is the same as the vibrational frequency of a bond or collection of bonds, absorption occurs. Examination of the transmitted light reveals how much energy was absorbed at each frequency (or wavelength). This measurement can be achieved by scanning the wavelength range using a monochromator. Alternatively, the entire wavelength range is measured using a Fourier transform instrument and then a transmittance or absorbance spectrum is generated using a dedicated procedure.

This technique is commonly used for analyzing samples with covalent bonds. Simple spectra are obtained from samples with few IR active bonds and high levels of purity. More complex molecular structures lead to more absorption bands and more complex spectra.

Gas samples
Gaseous samples require a sample cell with a long pathlength to compensate for the diluteness. The pathlength of the sample cell depends on the concentration of the compound of interest. A simple glass tube with length of 5 to 10 cm equipped with infrared-transparent windows at both ends of the tube can be used for concentrations down to several hundred ppm. Sample gas concentrations well below ppm can be measured with a White's cell in which the infrared light is guided with mirrors to travel through the gas. White's cells are available with optical pathlength starting from 0.5 m up to hundred meters.

Liquid samples
Liquid samples can be sandwiched between two plates of a salt (commonly sodium chloride, or common salt, although a number of other salts such as potassium bromide or calcium fluoride are also used). The plates are transparent to the infrared light and do not introduce any lines onto the spectra. With increasing technology in computer filtering and manipulation of the results, samples in solution can now be measured accurately (water produces a broad absorbance across the range of interest, and thus renders the spectra unreadable without this computer treatment).

Solid samples
Solid samples can be prepared in a variety of ways. One common method is to crush the sample with an oily mulling agent (usually mineral oil Nujol). A thin film of the mull is applied onto salt plates and measured. The second method is to grind a quantity of the sample with a specially purified salt (usually potassium bromide) finely (to remove scattering effects from large crystals). This powder mixture is then pressed in a mechanical press to form a translucent pellet through which the beam of the spectrometer can pass. A third technique is the "cast film" technique, which is used mainly for polymeric materials. The sample is first dissolved in a suitable, non-hygroscopic solvent. A drop of this solution is deposited on the surface of a KBr or NaCl cell. The solution is then evaporated to dryness and the film formed on the cell is analysed directly. Care is important to ensure that the film is not too thick otherwise light cannot pass through. This technique is suitable for qualitative analysis. The final method is to use microtomy to cut a thin (20–100 μm) film from a solid sample. This is one of the most important ways of analysing failed plastic products for example because the integrity of the solid is preserved.

In photoacoustic spectroscopy the need for sample treatment is minimal. The sample, liquid or solid, is placed into the sample cup which is inserted into the photoacoustic cell which is then sealed for the measurement. The sample may be one solid piece, powder or basically in any form for the measurement. For example, a piece of rock can be inserted into the sample cup and the spectrum measured from it.

A useful way of analyzing solid samples without the need for cutting samples uses ATR or attenuated total reflectance spectroscopy. Using this approach, samples are pressed against the face of a single crystal. The infrared radiation passes through the crystal and only interacts with the sample at the interface between the two materials.

Comparing to a reference
It is typical to record spectrum of both the sample and a "reference". This step controls for a number of variables, e.g. infrared detector, which may affect the spectrum. The reference measurement makes it possible to eliminate the instrument influence.

The appropriate "reference" depends on the measurement and its goal. The simplest reference measurement is to simply remove the sample (replacing it by air). However, sometimes a different reference is more useful. For example, if the sample is a dilute solute dissolved in water in a beaker, then a good reference measurement might be to measure pure water in the same beaker. Then the reference measurement would cancel out not only all the instrumental properties (like what light source is used), but also the light-absorbing and light-reflecting properties of the water and beaker, and the final result would just show the properties of the solute (at least approximately).

A common way to compare to a reference is sequentially: first measure the reference, then replace the reference by the sample and measure the sample. This technique is not perfectly reliable; if the infrared lamp is a bit brighter during the reference measurement, then a bit dimmer during the sample measurement, the measurement will be distorted. More elaborate methods, such as a "two-beam" setup (see figure), can correct for these types of effects to give very accurate results. The Standard addition method can be used to statistically cancel these errors.

Nevertheless, among different absorption-based techniques which are used for gaseous species detection, Cavity ring-down spectroscopy (CRDS) can be used as a calibration-free method. The fact that CRDS is based on the measurements of photon life-times (and not the laser intensity) makes it needless for any calibration and comparison with a reference

Some instruments also automatically identify the substance being measured from a store of thousands of reference spectra held in storage.

FTIR
Fourier transform infrared (FTIR) spectroscopy is a measurement technique that allows one to record infrared spectra. Infrared light is guided through an interferometer and then through the sample (or vice versa). A moving mirror inside the apparatus alters the distribution of infrared light that passes through the interferometer. The signal directly recorded, called an "interferogram", represents light output as a function of mirror position. A data-processing technique called Fourier transform turns this raw data into the desired result (the sample's spectrum): light output as a function of infrared wavelength (or equivalently, wavenumber). As described above, the sample's spectrum is always compared to a reference.

An alternate method for acquiring spectra is the "dispersive" or "scanning monochromator" method. In this approach, the sample is irradiated sequentially with various single wavelengths. The dispersive method is more common in UV-Vis spectroscopy, but is less practical in the infrared than the FTIR method. One reason that FTIR is favored is called "Fellgett's advantage" or the "multiplex advantage": The information at all frequencies is collected simultaneously, improving both speed and signal-to-noise ratio. Another is called "Jacquinot's Throughput Advantage": A dispersive measurement requires detecting much lower light levels than an FTIR measurement. There are other advantages, as well as some disadvantages, but virtually all modern infrared spectrometers are FTIR instruments.

Infrared microscopy
Various forms of infrared microscopy exist. These include IR versions of sub-diffraction microscopy such as IR NSOM, photothermal microspectroscopy, Nano-FTIR and atomic force microscope based infrared spectroscopy (AFM-IR).

Other methods in molecular vibrational spectroscopy
Infrared spectroscopy is not the only method of studying molecular vibrational spectra. Raman spectroscopy involves an inelastic scattering process in which only part of the energy of an incident photon is absorbed by the molecule, and the remaining part is scattered and detected. The energy difference corresponds to absorbed vibrational energy.

The selection rules for infrared and for Raman spectroscopy are different at least for some molecular symmetries, so that the two methods are complementary in that they observe vibrations of different symmetries.

Another method is electron energy loss spectroscopy (EELS), in which the energy absorbed is provided by an inelastically scattered electron rather than a photon. This method is useful for studying vibrations of molecules adsorbed on a solid surface.

Recently, high-resolution EELS (HREELS) has emerged as a technique for performing vibrational spectroscopy in a transmission electron microscope (TEM). In combination with the high spatial resolution of the TEM, unprecedented experiments have been performed, such as nano-scale temperature measurements, mapping of isotopically labeled molecules, mapping of phonon modes in position- and momentum-space,  vibrational surface and bulk mode mapping on nanocubes, and investigations of polariton modes in van der Waals crystals. Analysis of vibrational modes that are IR-inactive but appear in inelastic neutron scattering is also possible at high spatial resolution using EELS. Although the spatial resolution of HREELs is very high, the bands are extremely broad compared to other techniques.

Computational infrared microscopy
By using computer simulations and normal mode analysis it is possible to calculate theoretical frequencies of molecules.

Absorption bands
IR spectroscopy is often used to identify structures because functional groups give rise to characteristic bands both in terms of intensity and position (frequency). The positions of these bands are summarized in correlation tables as shown below.

Regions
A spectrograph is often interpreted as having two regions. In the functional region there are one to a few troughs per functional group. In the fingerprint region there are many troughs which form an intricate pattern which can be used like a fingerprint to determine the compound.
 * functional group region $$\geq 1,500 \text{ cm}^{-1}$$
 * fingerprint region $$ < 1,500 \text{ cm}^{-1}$$

Badger's rule
For many kinds of samples, the assignments are known, i.e. which bond deformation(s) are associated with which frequency. In such cases further information can be gleaned about the strength on a bond, relying on the empirical guideline called Badger's rule. Originally published by Richard McLean Badger in 1934, this rule states that the strength of a bond (in terms of force constant) correlates with the bond length. That is, increase in bond strength leads to corresponding bond shortening and vice versa.

Isotope effects
The different isotopes in a particular species may exhibit different fine details in infrared spectroscopy. For example, the O–O stretching frequency (in reciprocal centimeters) of oxyhemocyanin is experimentally determined to be 832 and 788 cm−1 for ν(16O–16O) and ν(18O–18O), respectively.

By considering the O–O bond as a spring, the frequency of absorbance can be calculated as a wavenumber [= frequency/(speed of light)]

 * $$\tilde{\nu} = \frac{1}{2 \pi c} \sqrt{\frac{k}{\mu}}$$

where k is the spring constant for the bond, c is the speed of light, and μ is the reduced mass of the A–B system:

 * $$\mu = \frac{m_\mathrm A m_\mathrm B}{m_\mathrm A + m_\mathrm B}$$

($$m_i$$ is the mass of atom $$i$$).

The reduced masses for 16O–16O and 18O–18O can be approximated as 8 and 9 respectively. Thus

 * $$\frac{\tilde{\nu}(^{16}\mathrm O)}{\tilde{\nu}(^{18}\mathrm O)} = \sqrt{\frac{9}{8}} \approx \frac{832}{788}.$$

The effect of isotopes, both on the vibration and the decay dynamics, has been found to be stronger than previously thought. In some systems, such as silicon and germanium, the decay of the anti-symmetric stretch mode of interstitial oxygen involves the symmetric stretch mode with a strong isotope dependence. For example, it was shown that for a natural silicon sample, the lifetime of the anti-symmetric vibration is 11.4 ps. When the isotope of one of the silicon atoms is increased to 29Si, the lifetime increases to 19 ps. In similar manner, when the silicon atom is changed to 30Si, the lifetime becomes 27 ps.

Two-dimensional IR
Two-dimensional infrared correlation spectroscopy analysis combines multiple samples of infrared spectra to reveal more complex properties. By extending the spectral information of a perturbed sample, spectral analysis is simplified and resolution is enhanced. The 2D synchronous and 2D asynchronous spectra represent a graphical overview of the spectral changes due to a perturbation (such as a changing concentration or changing temperature) as well as the relationship between the spectral changes at two different wavenumbers.

Nonlinear two-dimensional infrared spectroscopy is the infrared version of correlation spectroscopy. Nonlinear two-dimensional infrared spectroscopy is a technique that has become available with the development of femtosecond infrared laser pulses. In this experiment, first a set of pump pulses is applied to the sample. This is followed by a waiting time during which the system is allowed to relax. The typical waiting time lasts from zero to several picoseconds, and the duration can be controlled with a resolution of tens of femtoseconds. A probe pulse is then applied, resulting in the emission of a signal from the sample. The nonlinear two-dimensional infrared spectrum is a two-dimensional correlation plot of the frequency ω1 that was excited by the initial pump pulses and the frequency ω3 excited by the probe pulse after the waiting time. This allows the observation of coupling between different vibrational modes; because of its extremely fine time resolution, it can be used to monitor molecular dynamics on a picosecond timescale. It is still a largely unexplored technique and is becoming increasingly popular for fundamental research.

As with two-dimensional nuclear magnetic resonance (2DNMR) spectroscopy, this technique spreads the spectrum in two dimensions and allows for the observation of cross peaks that contain information on the coupling between different modes. In contrast to 2DNMR, nonlinear two-dimensional infrared spectroscopy also involves the excitation to overtones. These excitations result in excited state absorption peaks located below the diagonal and cross peaks. In 2DNMR, two distinct techniques, COSY and NOESY, are frequently used. The cross peaks in the first are related to the scalar coupling, while in the latter they are related to the spin transfer between different nuclei. In nonlinear two-dimensional infrared spectroscopy, analogs have been drawn to these 2DNMR techniques. Nonlinear two-dimensional infrared spectroscopy with zero waiting time corresponds to COSY, and nonlinear two-dimensional infrared spectroscopy with finite waiting time allowing vibrational population transfer corresponds to NOESY. The COSY variant of nonlinear two-dimensional infrared spectroscopy has been used for determination of the secondary structure content of proteins.

title: Infrared spectroscopy


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Irenaeus

Irenaeus (Εἰρηναῖος; c. 130) was a Greek bishop noted for his role in guiding and expanding Christian communities in the southern regions of present-day France and, more widely, for the development of Christian theology by combating heterodox or Gnostic interpretations of Scripture as heresy and defining proto-orthodoxy. Originating from Smyrna, he had seen and heard the preaching of Polycarp, who in turn was said to have heard John the Evangelist, and thus was the last-known living connection with the Apostles.

Chosen as bishop of Lugdunum, now Lyon, his best-known work is Against Heresies, often cited as Adversus Haereses, a refutation of gnosticism, in particular that of Valentinus. To counter the doctrines of the gnostic sects claiming secret wisdom, he offered three pillars of orthodoxy: the scriptures, the tradition handed down from the apostles, and the teaching of the apostles' successors. He is the earliest surviving witness to regard all four of the now-canonical gospels as essential.

Irenaeus is venerated as a saint in the Catholic Church and in the ancient Churches of the Christian East: the Eastern Orthodox Church, and the Oriental Orthodox Churches, including the Assyrian Church of the East.

The Latin Catholic Church celebrates his memorial on 28 June. Pope Francis declared Irenaeus the 37th Doctor of the Church on 21 January 2022.

The Eastern Orthodox Church celebrates Irenaeus, the feast being also on 23 August.

Irenaeus is honored in the Church of England and in the Episcopal Church on 28 June.

Biography
Irenaeus was a Greek from Polycarp's hometown of Smyrna in Asia Minor, now İzmir, Turkey, born during the first half of the 2nd century. The exact date is thought to be between the years 120 and 140. Unlike many of his contemporaries, he was brought up in a Christian family rather than converting as an adult.

During the persecution of Christians by Marcus Aurelius, the Roman emperor from 161 to 180, Irenaeus was a priest of the Church of Lyon. The clergy of that city, many of whom were suffering imprisonment for the faith, sent him in 177 to Rome with a letter to Pope Eleutherius concerning the heresy of Montanism, and that occasion bore emphatic testimony to his merits. While Irenaeus was in Rome, a persecution took place in Lyon. Returning to Gaul, Irenaeus succeeded the martyr Saint Pothinus and became the second bishop of Lyon.

During the religious peace which followed the persecution by Marcus Aurelius, the new bishop divided his activities between the duties of a pastor and of a missionary (as to which we have but brief data, late and not very certain). Almost all his writings were directed against Gnosticism. The most famous of these writings is Adversus haereses (Against Heresies). Irenaeus alludes to coming across Gnostic writings, and holding conversations with Gnostics, and this may have taken place in Asia Minor or in Rome. However, it also appears that Gnosticism was present near Lyon: he writes that there were followers of 'Marcus the Magician' living and teaching in the Rhone valley.

Little is known about the career of Irenaeus after he became bishop. The last action reported of him (by Eusebius, 150 years later) is that in 190 or 191, he exerted influence on Pope Victor I not to excommunicate the Christian communities of Asia Minor which persevered in the practice of the Quartodeciman celebration of Easter.

Nothing is known of the date of his death, which must have occurred at the end of the second or the beginning of the third century. He is regarded as a martyr by the Catholic Church and by some within the Orthodox Church. He was buried under the Church of Saint John in Lyon, which was later renamed St Irenaeus in his honour. The church was devastated in 1562 by the Huguenots. Several relics supposedly of Irenaeus are held in various churches in Lyon. Two crania from different churches were dated by carbon-14 to the Middle Ages, but a piece of heelbone kept in the Lyon Cathedral is from the right time period.

Writings
Irenaeus wrote a number of books, but the most important that survives is the Against Heresies (or, in its Latin title, Adversus haereses). In Book I, Irenaeus talks about the Valentinian Gnostics and their predecessors, who he says go as far back as the magician Simon Magus. In Book II he attempts to provide proof that Valentinianism contains no merit in terms of its doctrines. In Book III Irenaeus purports to show that these doctrines are false, by providing counter-evidence gleaned from the Gospels. Book IV consists of Jesus's sayings, and here Irenaeus also stresses the unity of the Old Testament and the Gospel. In the final volume, Book V, Irenaeus focuses on more sayings of Jesus plus the letters of Paul the Apostle.

Irenaeus wrote: "One should not seek among others the truth that can be easily gotten from the Church. For in her, as in a rich treasury, the apostles have placed all that pertains to truth, so that everyone can drink this beverage of life. She is the door of life." But he also said, "Christ came not only for those who believed from the time of Tiberius Caesar, nor did the Father provide only for those who are now, but for absolutely all men from the beginning, who, according to their ability, feared and loved God and lived justly. . . and desired to see Christ and to hear His voice."

The purpose of "Against Heresies" was to refute the teachings of various Gnostic groups; apparently, several Greek merchants had begun an oratorial campaign in Irenaeus's bishopric, teaching that the material world was the accidental creation of an evil god, from which we are to escape by the pursuit of gnosis. Irenaeus argued that the true gnosis is in fact knowledge of Christ, which redeems rather than escapes from bodily existence.

Until the discovery of the Library of Nag Hammadi in 1945, Against Heresies was the best-surviving description of Gnosticism. Some religious scholars have argued the findings at Nag Hammadi have shown Irenaeus's description of Gnosticism to be inaccurate and polemic in nature. However, the general consensus among modern scholars is that Irenaeus was fairly accurate in his transmission of gnostic beliefs, and that the Nag Hammadi texts have raised no substantial challenges to the overall accuracy of Irenaeus's information. Religious historian Elaine Pagels criticizes Irenaeus for describing Gnostic groups as sexual libertines, for example, when some of their own writings advocated chastity more strongly than did orthodox texts. However, the Nag Hammadi texts do not present a single, coherent picture of any unified gnostic system of belief, but rather divergent beliefs of multiple Gnostic sects. Some of these sects were indeed libertine because they considered bodily existence meaningless; others praised chastity, and strongly prohibited any sexual activity, even within marriage.

Irenaeus also wrote The Demonstration of the Apostolic Preaching (also known as Proof of the Apostolic Preaching), an Armenian copy of which was discovered in 1904. This work seems to have been an instruction for recent Christian converts.

Eusebius attests to other works by Irenaeus, today lost, including On the Ogdoad, an untitled letter to Blastus regarding schism, On the Subject of Knowledge, On the Monarchy or How God is not the Cause of Evil, On Easter.

Irenaeus exercised wide influence on the generation which followed. Both Hippolytus and Tertullian freely drew on his writings. However, none of his works aside from Against Heresies and The Demonstration of the Apostolic Preaching survive today, perhaps because his literal hope of an earthly millennium may have made him uncongenial reading in the Greek East. Even though no complete version of Against Heresies in its original Greek exists, we possess the full ancient Latin version, probably of the third century, as well as thirty-three fragments of a Syrian version and a complete Armenian version of books 4 and 5.

Evelyn Underhill in her book Mysticism credited Irenaeus as being one of those to whom we owe "the preservation of that mighty system of scaffolding which enabled the Catholic mystics to build up the towers and bulwarks of the City of God."

Irenaeus's works were first translated into English by John Keble and published in 1872 as part of the Library of the Fathers series.

Scripture
Irenaeus pointed to the public rule of faith, authoritatively articulated by the preaching of bishops and inculcated in Church practice, especially worship, as an authentic apostolic tradition by which to read Scripture truly against heresies. He classified as Scripture not only the Old Testament but most of the books now known as the New Testament, while excluding many works, a large number by Gnostics, that flourished in the 2nd century and claimed scriptural authority. Oftentimes, Irenaeus, as a student of Polycarp, who was a direct disciple of the Apostle John, believed that he was interpreting scriptures in the same hermeneutic as the Apostles. This connection to Jesus was important to Irenaeus because both he and the Gnostics based their arguments on Scripture. Irenaeus argued that since he could trace his authority to Jesus and the Gnostics could not, his interpretation of Scripture was correct. He also used "the Rule of Faith", a "proto-creed" with similarities to the Apostles' Creed, as a hermeneutical key to argue that his interpretation of Scripture was correct.

Before Irenaeus, Christians differed as to which gospel they preferred. The Christians of Asia Minor preferred the Gospel of John. The Gospel of Matthew was the most popular overall. Irenaeus asserted that all four of the Gospels, John, Luke, Matthew, and Mark (which is the order presented in his four pillar narrative in Adversus haereses (Against Heresies) III 11,8), were canonical scripture. Thus Irenaeus provides the earliest witness to the assertion of the four canonical Gospels, possibly in reaction to Marcion's edited version of the Gospel of Luke, which Marcion asserted was the one and only true gospel.

Based on the arguments Irenaeus made in support of only four authentic gospels, some interpreters deduce that the fourfold Gospel must have still been a novelty in Irenaeus's time. Against Heresies 3.11.7 acknowledges that many heterodox Christians use only one gospel while 3.11.9 acknowledges that some use more than four. The success of Tatian's Diatessaron in about the same time period is "... a powerful indication that the fourfold Gospel contemporaneously sponsored by Irenaeus was not broadly, let alone universally, recognized." (The apologist and ascetic Tatian had previously harmonized the four gospels into a single narrative, the Diatesseron c. 150–160)

Irenaeus is also the earliest attestation that the Gospel of John was written by John the Apostle, and that the Gospel of Luke was written by Luke, the companion of Paul.

Scholars contend that Irenaeus quotes from 21 of the 27 New Testament books, such as:

 * Matthew 3:16
 * Mark 3:10
 * Luke 3:14
 * John 3:11
 * Acts of the Apostles 3:14
 * Romans 3:16
 * 1 Corinthians 1:3
 * 2 Corinthians 3:7
 * Galatians 3:22
 * Ephesians 5:2
 * Philippians 4:18
 * Colossians 1:3
 * 1 Thessalonians 5:6
 * 2 Thessalonians 5:25
 * 1 Timothy (Preface)
 * 2 Timothy 3:14
 * Titus 3:3
 * 1 Peter 4:9
 * 1 John 3:16
 * 2 John 1:16
 * Revelation 4:20

He may refer to Hebrews 2:30 and James 4:16 and maybe even 2 Peter 5:28, but does not cite Philemon.

Irenaeus cited the New Testament approximately 1,000 times. About one third of his citations are made to Paul's letters. Irenaeus considered all 13 letters belonging to the Pauline corpus to have been written by Paul himself.

Apostolic authority

In his writing against the Gnostics, who claimed to possess a secret oral tradition from Jesus himself, Irenaeus maintained that the bishops in different cities are known as far back as the Apostles and that the oral tradition he lists from the Apostles is a safe guide to the interpretation of Scripture. In a passage that became a locus classicus of Catholic-Protestant polemics, he cited the Roman church as an example of the unbroken chain of authority, which text Catholic polemics would use to assert the primacy of Rome over Eastern churches by virtue of its preeminent authority. The succession of bishops and presbyters was important to establish a chain of custody for orthodoxy.

Irenaeus's point when refuting the Gnostics was that all of the Apostolic churches had preserved the same traditions and teachings in many independent streams. It was the unanimous agreement between these many independent streams of transmission that proved the orthodox faith, current in those churches, to be true.

Theology and contrast with Gnosticism
The central point of Irenaeus's theology is the unity and the goodness of God, in opposition to the Gnostics' theory of God; a number of divine emanations (Aeons) along with a distinction between the Monad and the Demiurge. Irenaeus uses the Logos theology he inherited from Justin Martyr. Irenaeus was a student of Polycarp, who was said to have been tutored by John the Apostle. (John had used Logos terminology in the Gospel of John and the letter of 1 John). Irenaeus often spoke of the Son and the Spirit as the "hands of God," though he also spoke of the Son as the "Logos."

Unity of salvation history
Irenaeus's emphasis on the unity of God is reflected in his corresponding emphasis on the unity of salvation history. Irenaeus repeatedly insists that God began the world and has been overseeing it ever since this creative act; everything that has happened is part of his plan for humanity. The essence of this plan is a process of maturation: Irenaeus believes that humanity was created immature, and God intended his creatures to take a long time to grow into or assume the divine likeness.

Everything that has happened since has therefore been planned by God to help humanity overcome this initial mishap and achieve spiritual maturity. The world has been intentionally designed by God as a difficult place, where human beings are forced to make moral decisions, as only in this way can they mature as moral agents. Irenaeus likens death to the big fish that swallowed Jonah: it was only in the depths of the whale's belly that Jonah could turn to God and act according to the divine will. Similarly, death and suffering appear as evils, but without them we could never come to know God.

According to Irenaeus, the high point in salvation history is the advent of Jesus. For Irenaeus, the Incarnation of Christ was intended by God before he determined that humanity would be created. Irenaeus develops this idea based on [https://www.biblegateway.com/passage/?search=Romans+5%3A14&version=NRSVCE Rom. 5:14], saying "Forinasmuch as He had a pre-existence as a saving Being, it was necessary that what might be saved should also be called into existence, in order that the Being who saves should not exist in vain." Some theologians maintain that Irenaeus believed that Incarnation would have occurred even if humanity had never sinned; but the fact that they did sin determined his role as the savior.

Irenaeus sees Christ as the new Adam, who systematically undoes what Adam did: thus, where Adam was disobedient concerning God's edict concerning the fruit of the Tree of Knowledge of Good and Evil, Christ was obedient even to death on the wood of a tree. Irenaeus is the first to draw comparisons between Eve and Mary, contrasting the faithlessness of the former with the faithfulness of the latter. In addition to reversing the wrongs done by Adam, Irenaeus thinks of Christ as "recapitulating" or "summing up" human life.

Irenaeus conceives of our salvation as essentially coming about through the incarnation of God as a man. He characterizes the penalty for sin as death and corruption. God, however, is immortal and incorruptible, and simply by becoming united to human nature in Christ he conveys those qualities to us: they spread, as it were, like a benign infection. Irenaeus emphasizes that salvation occurs through Christ's Incarnation, which bestows incorruptibility on humanity, rather than emphasizing His Redemptive death in the crucifixion, although the latter event is an integral part of the former.

Christ's life
Part of the process of recapitulation is for Christ to go through every stage of human life, from infancy to old age, and simply by living it, sanctify it with his divinity. Although it is sometimes claimed that Irenaeus believed Christ did not die until he was older than is conventionally portrayed, the bishop of Lyon simply pointed out that because Jesus turned the permissible age for becoming a rabbi (30 years old and above), he recapitulated and sanctified the period between 30 and 50 years old, as per the Jewish custom of periodization on life, and so touches the beginning of old age when one becomes 50 years old. (see Adversus Haereses, book II, chapter 22).

In the passage of Adversus Haereses under consideration, Irenaeus is clear that after receiving baptism at the age of thirty, citing Luke 3:23, Gnostics then falsely assert that "He [Jesus] preached only one year reckoning from His baptism," and also, "On completing His thirtieth year He [Jesus] suffered, being in fact still a young man, and who had by no means attained to advanced age." Irenaeus argues against the Gnostics by using scripture to add several years after his baptism by referencing 3 distinctly separate visits to Jerusalem. The first is when Jesus makes wine out of water, he goes up to the Paschal feast-day, after which he withdraws and is found in Samaria. The second is when Jesus goes up to Jerusalem for Passover and cures the paralytic, after which he withdraws over the sea of Tiberias. The third mention is when he travels to Jerusalem, eats the Passover, and suffers on the following day.

Irenaeus quotes scripture (John 8:57), to suggest that Jesus ministers while in his 40s. In this passage, Jesus's opponents want to argue that Jesus has not seen Abraham, because Jesus is too young. Jesus's opponents argue that Jesus was not yet 50 years old. Irenaeus argues that if Jesus were in his thirties, his opponents would have argued that he was not yet 40 years old, since that would make him even younger. Irenaeus's argument is that they would not weaken their own argument by adding years to Jesus's age. Irenaeus also writes: "The Elders witness to this, who in Asia conferred with John the Lord's disciple, to the effect that John had delivered these things unto them: for he abode with them until the times of Trajan. And some of them saw not only John, but others also of the Apostles, and had this same account from them, and witness to the aforesaid relation."

In Demonstration (74) Irenaeus notes "For Pontius Pilate was governor of Judæa, and he had at that time resentful enmity against Herod the king of the Jews. But then, when Christ was brought to him bound, Pilate sent Him to Herod, giving command to enquire of him, that he might know of a certainty what he should desire concerning Him; making Christ a convenient occasion of reconciliation with the king." Pilate was the prefect of the Roman province of Judaea from AD 26–36. He served under Emperor Tiberius Claudius Nero. Herod Antipas was tetrarch of Galilee and Perea, a client state of the Roman Empire. He ruled from 4 BC to 39 AD. In refuting Gnostic claims that Jesus preached for only one year after his baptism, Irenaeus used the "recapitulation" approach to demonstrate that by living beyond the age of thirty Christ sanctified even old age.

Use of Paul's Epistles
Many aspects of Irenaeus's presentation of salvation history depend on Paul's Epistles.

Irenaeus's conception of salvation relies heavily on the understanding found in Paul's letters. Irenaeus first brings up the theme of victory over sin and evil that is afforded by Jesus's death. God's intervention has saved humanity from the Fall of Adam and the wickedness of Satan. Human nature has become joined with God's in the person of Jesus, thus allowing human nature to have victory over sin. Paul writes on the same theme, that Christ has come so that a new order is formed, and being under the Law, is being under the sin of Adam.

Reconciliation is also a theme of Paul's that Irenaeus stresses in his teachings on Salvation. Irenaeus believes Jesus coming in flesh and blood sanctified humanity so that it might again reflect the perfection associated with the likeness of the Divine. This perfection leads to a new life, in the lineage of God, which is forever striving for eternal life and unity with the Father. This is a carryover from Paul, who attributes this reconciliation to the actions of Christ: "For since death came through a human being, the resurrection of the dead has also come through a human being; for as all die in Adam, so all will be made alive in Christ".

A third theme in both Paul's and Irenaeus's conceptions of salvation is the sacrifice of Christ being necessary for the new life given to humanity in the triumph over evil. It is in this obedient sacrifice that Jesus is victor and reconciler, thus erasing the marks that Adam left on human nature. To argue against the Gnostics on this point, Irenaeus uses Colossians in showing that the debt which came by a tree has been paid for us in another tree. Furthermore, the first chapter of Ephesians is picked up in Irenaeus's discussion of the topic when he asserts, "By His own blood He redeemed us, as also His apostle declares, 'In whom we have redemption through His blood, even the remission of sins.'"

The frequencies of quotations and allusions to the Pauline Epistles in Against Heresies are:

Christ as the New Adam
To counter his Gnostic opponents, Irenaeus significantly develops Paul's presentation of Christ as the Last Adam.

Irenaeus's presentation of Christ as the New Adam is based on Paul's Christ-Adam parallel in. Irenaeus uses this parallel to demonstrate that Christ truly took human flesh. Irenaeus considered it important to emphasize this point because he understands the failure to recognize Christ's full humanity the bond linking the various strains of Gnosticism together, as seen in his statement that "according to the opinion of no one of the heretics was the Word of God made flesh." Irenaeus believes that unless the Word became flesh, humans were not fully redeemed. He explains that by becoming man, Christ restored humanity to being in the image and likeness of God, which they had lost in the Fall of man. Just as Adam was the original head of humanity through whom all sinned, Christ is the new head of humanity who fulfills Adam's role in the Economy of Salvation. Irenaeus calls this process of restoring humanity recapitulation.

For Irenaeus, Paul's presentation of the Old Law (the Mosaic covenant) in this passage indicates that the Old Law revealed humanity's sinfulness but could not save them. He explains that "For as the law was spiritual, it merely made sin to stand out in relief, but did not destroy it. For sin had no dominion over the spirit, but over man." Since humans have a physical nature, they cannot be saved by a spiritual law. Instead, they need a human Savior. This is why it was necessary for Christ to take human flesh. Irenaeus summarizes how Christ's taking human flesh saves humanity with a statement that closely resembles, "For as by the disobedience of the one man who was originally moulded from virgin soil, the many were made sinners, and forfeited life; so was it necessary that, by the obedience of one man, who was originally born from a virgin, many should be justified and receive salvation." The physical creation of Adam and Christ is emphasized by Irenaeus to demonstrate how the Incarnation saves humanity's physical nature.

Irenaeus emphasizes the importance of Christ's reversal of Adam's action. Through His obedience, Christ undoes Adam's disobedience. Irenaeus presents the Passion as the climax of Christ's obedience, emphasizing how this obedience on the tree of the Cross undoes the disobedience that occurred through a tree.

Irenaeus's interpretation of Paul's discussion of Christ as the New Adam is significant because it helped develop the recapitulation theory of atonement. Irenaeus emphasizes that it is through Christ's reversal of Adam's action that humanity is saved, rather than considering the Redemption to occur in a cultic or juridical way.

The biblical passage, "Death has been swallowed up in victory", implied for Irenaeus that the Lord will surely resurrect the first human, i.e. Adam, as one of the saved. According to Irenaeus, those who deny Adam's salvation are “shutting themselves out from life for ever” and the first one who did so was Tatian. The notion that the Second Adam saved the first Adam was advocated not only by Irenaeus, but also by Gregory Thaumaturgus, which suggests that it was popular in the Early Church.

Valentinian Gnosticism
Valentinian Gnosticism was one of the major forms of Gnosticism that Irenaeus opposed.

According to the Gnostic view of Salvation, creation was perfect to begin with; it did not need time to grow and mature. For the Valentinians, the material world is the result of the loss of perfection which resulted from Sophia's desire to understand the Forefather. Therefore, one is ultimately redeemed, through secret knowledge, to enter the pleroma of which the Achamoth originally fell.

According to the Valentinian Gnostics, there are three classes of human beings. They are the material, who cannot attain salvation; the psychic, who are strengthened by works and faith (they are part of the church); and the spiritual, who cannot decay or be harmed by material actions. Essentially, ordinary humans—those who have faith but do not possess the special knowledge—will not attain salvation. Spirituals, on the other hand—those who obtain this great gift—are the only class that will eventually attain salvation.

In his article entitled "The Demiurge", J.P. Arendzen sums up the Valentinian view of the salvation of man. He writes, "The first, or carnal men, will return to the grossness of matter and finally be consumed by fire; the second, or psychic men, together with the Demiurge as their master, will enter a middle state, neither heaven (pleroma) nor hell (whyle); the purely spiritual men will be completely freed from the influence of the Demiurge and together with the Saviour and Achamoth, his spouse, will enter the pleroma divested of body (húle) and soul (psuché)."

In this understanding of salvation, the purpose of the Incarnation was to redeem the Spirituals from their material bodies. By taking a material body, the Son becomes the Savior and facilitates this entrance into the pleroma by making it possible for the Spirituals to receive his spiritual body. However, in becoming a body and soul, the Son Himself becomes one of those needing redemption. Therefore, the Word descends onto the Savior at His Baptism in the Jordan, which liberates the Son from his corruptible body and soul. His redemption from the body and soul is then applied to the Spirituals. In response to this Gnostic view of Christ, Irenaeus emphasized that the Word became flesh and developed a soteriology that emphasized the significance of Christ's material Body in saving humanity, as discussed in the sections above.

In his criticism of Gnosticism, Irenaeus made reference to a Gnostic gospel which portrayed Judas in a positive light, as having acted in accordance with Jesus's instructions. The recently discovered Gospel of Judas dates close to the period when Irenaeus lived (late 2nd century), and scholars typically regard this work as one of many Gnostic texts, showing one of many varieties of Gnostic beliefs of the period.

Quartodeciman Controversy
Irenaeus took part in the Quartodeciman Controversy. When Victor I of Rome tried to force a universal practice of fasting until Easter to supersede the Jewish practice and prevent Christians from partaking of the Passover, Polycrates who led the Churches of Asia Minor continued to hold old traditions of the paschal feast. For this reason Victor I wanted to excommunicate Polycrates and his supporters, but this was a step too far for Irenaeus and other bishops.

title: Irenaeus


text:
Talk:I Have a Dream

history
What was  martin   dream  about  america 197.186.5.140 (talk) 17:36, 15 May 2022 (UTC)

Dr. King's later thoughts on the speech
Having quickly glanced through the article, I've noticed that there is an absence regarding Dr. King's later thoughts on the speech (particularly those he reiterated in his 1967 interview with Sander Vanocur). To summarize, he said that his 'dream' has "...at many points turned into a nightmare..." and regarded the speech as overly optimistic, in light of the resistances to further civil rights advancements and the Vietnam War, both of which he viewed as parts of or results of the evils (his 'Triple Evils' as he called them) he thought the USA was complicit in. All in all, he had essentially disavowed his speech - prior to directly commenting on the speech, he mentioned that integration as a sole focus of the Civil Rights movement wasn't enough without a "revolution of values" and quoted James Baldwin, saying "What advantage is there in being integrated into a burning house?" The interview can be found here. With all of that said - considering this interview, as well as Dr. King's later stances prior to the end of his life, I believe this should be noted in the article under the 'Legacy' section. Also something of note is how it is often misconstrued by modern-day conservatives as an advocacy of solving racism via a 'colorblind' approach to society (rather than seeing 'colorblindness' as an end goal to strive towards). I can understand the latter not being included but I think it is important for the article to include King's own later thoughts on the speech as a good way to show what he thought about the progress made during that time. Kyle Tatum (talk) 05:27, 6 October 2022 (UTC)

Time
Hello! I am a student, and I can't find information about what time Martin Luther gave his speech. Does anyone know any information about this? If the information is somewhat known, maybe it could be put up with the date at the top of the page? David S. Petersen (talk) 18:19, 5 December 2023 (UTC)

title: Talk:I Have a Dream