Raphaël Marion

Kevin M Dunseath

Mariko Terao-Dunseath

Xavier Urbain
email: xavier.urbain@uclouvain.be

Absolute cross sections and asymmetry parameters

Keywords: numbers: 32.80.Gc, 31.10.+z, 33.60+q

teaching and research institutions in France or abroad, or from public or private research centers.

I. INTRODUCTION

The study of the photodetachment of negative ions, especially of open-shell systems such as carbon and oxygen, presents a double interest: they play an important role in astrophysics and atmospheric physics [1], and provide stringent tests for the description of electron correlation.

The electron affinity, or energy difference between the ground states of the negative ion and the residual atom, is indeed much smaller than the ionization energy of atoms and cations. While the variational principle applies independently for each system, it is much more difficult to guarantee a well-balanced calculation for both systems, and hence an accurate value for the electron affinity.

A comprehensive review of the knowledge of the structure and dynamics of atomic anions has been compiled by Andersen [2], who focused in particular on the decade between 1994 and 2004. In the case of O -, there was a long-standing discrepancy between experiment and theory, which was only recently resolved by new measurements using the Animated Crossed Beam technique to determine absolute total cross sections [3]. These are about 17% larger than the earlier data, and are in very good agreement with new theoretical results presented in the same publication. Since the most extensive set of experimental near-threshold photodetachment cross sections for C -( 4 S o ) dates back to 1962 and was normalized using the earlier data for O - [4], a direct measurement appears timely.

The carbon anion exists in two bound states: the ground state C -(1s 2 2s 2 2p 3 4 S o ), which has an affinity of 1.2621226 (11) eV with respect to the C(1s 2 2s 2 2p 2 3 P 0 ) ground level [5], and an excited state C -(1s 2 2s 2 2p 3 2 D o ) which is very weakly bound by about 33 meV [6]. In this work, we consider only photodetachment from the 4 S o ground state. At low energy, this results in the ejection of a 2p bound electron into the s or d wave, leaving the residual atom in its ground state: C -(1s 2 2s 2 2p 3 4 S o )+γ → C(1s 2 2s 2 2p 2 3 P )+e -(ℓ = 0, 2). is deflected by an electrostatic field and the current is In the second mode, the VMI spectrometer is turned 111 on while working at a higher pulse energy (250 µJ) with 112 much shorter anion packets (1 µs) in order to increase 113 the signal-to-noise ratio (SNR). The photoelectrons are 114 extracted perpendicularly by an electrostatic plate and 115 directed to the electrostatic lens designed following [12].

116

The repeller electrode is split to correct the trajectory 117 of the anions as explained in [13]. Photoelectrons are 118 detected using a COBRA system [14], comprising three for the pulse starting at t = t p,Z is formally given by 152 ρ p (x, y, z, t; Z) = ρ(x, y, z; t p,Z )

× exp -σ x -∞ dx ′ v φ p (x ′ , y, z -Z, t - x -x ′ v ) .
The initial distribution of anions, ρ(x, y, z; t p,Z ), can be For a detector of neutrals located at a position x d far after the interaction zone, with an efficiency η and an active surface S d larger than the cross-sectional area of the anion beam, we can express the count of neutrals for a pulse p as

N p,Z = η dt S d dydz v ρ(x d , y, z; t p,Z ) × 1 -exp -σ x d -∞ dx ′ v φ p (x ′ , y, z -Z, t - x d -x ′ v ) . (1)
If the argument of the exponential in Eq. ( 1) is small enough so that a first order expansion is sufficient, the neutral count N p,Z is proportional to the cross section σ.

After normalizing N p,Z with respect to the current I p,Z

and energy E p,Z and integrating over all laser offsets Z, the remaining integrals involve only φ and ρ, which result in a constant scale factor whose determination does not require any further assumptions about the beam profiles.

We obtain the ACB expression for the photodetachment cross section:

σ ACB pulsed = 1 η Z ∆Z n Z nZ p=1 ω E p,Z ev I p,Z N p,Z . (2)
This highlights the major advantage of the ACB technique; the experimental cross section does not depend on the geometrical overlap of the beams, which is critical and difficult to measure accurately in standard beambeam interaction experiments.

For continuous lasers, the integration over pulse duration is irrelevant and the production rate R Z of neutrals is directly measured by the CEM and normalized to the power P Z of the laser beam at position Z instead of the pulse energy E p,Z , and to the anion current I Z :

σ ACB cont = 1 η Z ∆Z ω P Z ev I Z R Z . (3)

Saturation effects from a pulsed laser

The ACB technique has been successfully implemented and used to determine absolute cross sections for many electron-ion [START_REF] Defrance | Atomic and Plasma-Material Interaction Data for Fusion[END_REF][START_REF] Muller | [END_REF][17] and electron-atom [18,19] interactions as well as for the photodetachment of H - [20] and O - [3,11]. The few necessary assumptions that are satisfied in the case of continuous lasers however do not always hold for pulsed lasers: as the peak intensity may become

198 dt Z ω E p,Z 1 -exp -σ x d -∞ dx ′ v φ p ≡ σ v [1 -s p (σ)] .
Inserting this in Eq. ( 2) yields a self-consistent expression 199 for σ which must be solved by iteration, starting from 200 σ 0 = σ ACB , until a stationary value of the cross section 201 is reached:

202 σ i+1 = σ ACB 1 -s(σ i ) , (4)
where s(σ) is the correction for saturation averaged over

(-T p /2 ≤ t -t M ≤ T p /2) as 212 φ(x, y, z, t) = 2 T p 2 πw 2 0 cos 2 π t -t M T p × exp -2 x 2 + z 2 w 2 0 . (5)
The factor by which σ ACB must be multiplied to correct for saturation effects is shown in Fig. 2. Its effect is to slightly increase the apparent cross section, particularly at lower photon energies. Since assumptions concerning the beam profiles are needed to estimate the saturation correction, it may seem that the main advantage of the ACB technique is somehow lost. The corrections however remain small and the whole procedure can be validated by comparison with measurements using a continuous laser, which is not subject to saturation, or obtained with a pulsed laser at lower energy and/or higher frequency, as will be shown in Sec. IV.

C. Differential cross section measurements

In the case of detachment by linearly polarized light, in the dipole approximation, additional information provided by the angular distribution of photoelectrons can be conveniently summarized using the asymmetry parameter β,

dσ dΩ = σ 4π [1 + βP 2 (cos θ)] , (6)
relating the differential cross section dσ/dΩ to the total cross section σ, where P 2 is the second-order Legendre

η = #(n ∧ e ∧ l) #(e ∧ l) ; Var[η] = η(1 -η) #(e ∧ l) ,
where the symbol # stands for the number of coinci-273 dences of a given type. This estimate can be used to cal-

296 m = P [m d ≥ 1] = 1 -P [m d = 0] = 1 - mp P[m d = 0 |η, m p ] P[m p | m] =⇒ m = 1 -e -η m.
In the following, the quantity η m will be denoted by md .

297

The background contribution to md is estimated by duplicating the coincidence time window with an arbitrary delay and applying the same Poisson correction to the total number b T of neutrals detected out of coincidence during the same n Z pulses. With these definitions, the mean rate and variance for neutral detection per pulse NZ entering Eq. ( 2) is given by NZ = md,Z -bd,Z ;

Var NZ = md,Z + bd,Z n Z .
with md,Z = -ln(1 -mZ ) and bd,Z = -ln(1 -bZ ).

For continuous light, we have improved the estimate of the background compared to our previous setup [3] by implementing a mechanical shutter to measure al- The contribution of the variance of the signal to the variance of the experimental cross section is given by

ternatively
Var[σ pulsed ] = p,Z 1 n Z ∆Z η ω E p,Z ev I p,Z 2 Var[ Np,Z ] Var[σ cont ] = Z ∆Z η ω P Z ev I Z 2 Var[ RZ ].
Sufficient internal statistical precision is usually obtained by one Z-scan for a continuous laser and by 5 Z-scans for pulsed light.

A final source of uncertainties arises from the observed fluctuations of measured cross sections over different runs, which might be due to variations of spatial distributions, especially in the laser beam. Fortunately, these variations average to zero so that increasing the number of runs (a repeatability test) is sufficient to improve the external statistics and reach the objective of 2% uncertainty for a pulsed laser and 0.5% for a continuous laser. The final values are obtained by calculating the weighted average over several runs:

σACB pulsed = j σj Var[σ j ] j 1 Var[σ j ] ; (7)
Var[σ ACB pulsed ] = 1 j 1 Var[σ j ] . (8)
A summary of typical uncertainty values is presented 333 in Table I, following [START_REF]for Guides in Metrology, JCGM 100: Evaluation of Measurement Data -Guide to the Expression of Uncer-tainty in Measurement[END_REF] for the classifications and rules 334 for combining experimental uncertainties.

Asymmetry parameters 336

To the best of our knowledge, there are no reliable 337 statistical estimators for asymmetry parameters. Here

338

we propose one such estimator for N events.

339

We start from a general probability distribution in 340 spherical coordinates with azimuthal symmetry:

341 P(v, θ, φ) = p(v) 4πv 2 L ℓ=0 β ℓ P ℓ (cos θ) , (9)
normalized so that The right hand side of this equation can be interpreted as the expectation value E[X [ℓ] ] of X [ℓ] = (2ℓ + 1)P ℓ (cos θ)

with respect to the probability distribution P (v, θ, φ).

We can also define the variance of X [ℓ] as

Var[X [ℓ] ] = E[(X [ℓ] ) 2 ] -E[X [ℓ] ] 2 = (2ℓ + 1) 2 L ℓ ′ =0 ℓ ℓ ℓ ′ 0 0 0 2 β ℓ ′ -β 2 ℓ . ( 11
)
We now consider an experiment providing N independent observations θ i , i ∈ {1, . . . , N }, of the polar angle

θ. The sample mean βℓ = 1 N N i=1 X [ℓ] i = 2l + 1 N N i=1 P l (cos θ i ), (12)
is then an unbiased estimator which, following the Central Limit Theorem, converges to β ℓ as N → ∞. The experimental variance for large sample sizes is Var[X [ℓ] ]/N , which vanishes as N → ∞ so that the estimator is consistent. We note that the presence of the Wigner 3-j symbol in Eq. ( 11) implies that the precision of βℓ is blurred by all the even distributions P ℓ ′ (cos θ) with ℓ ′ even between 0 and 2ℓ.

In the specific case of photodetachment by linearly polarized light, the dipole selection rules lead to the expression (6) for the differential cross section, which involves only ℓ = 0 and 2. Since β 0 = 1, β 2 is known as the asymmetry parameter commonly denoted β. For the same reasons, the upper limit of the summations over ℓ or ℓ ′ in Eqs. ( 9) and ( 11) is L = 2. The statistical precision for the estimation of β, from Eq. ( 11) with ℓ = 2, only contains contributions from ℓ ′ = 0 and 2, leading to

5 N + 10 β 7N - β2 N . (13)
These results, however, cannot be directly applied to our data since the spherical distribution itself is not known experimentally, only its projection. The Abel inversion provided by the maximum entropy (MAXENT) approach [22] gives an estimate of the distribution in an un-normalized form:

P(v, θ, φ) = 1 4πv 2 [Q 0 (v) + Q 2 (v)P 2 (cos θ)] . (14)
Integrating Eq. ( 14) over the velocity space gives the total number of events N = Q 0 (v)dv, while direct comparison with Eq. ( 9) yields an estimate β

(v) = Q 2 (v) Q 0 (v).
The dependency of β on v, which arises from the unavoidable dispersion associated with the limited precision of the experimental setup, prevents a direct determination of the best and unique value of the asymmetry parameter and its precision from Q 0 (v) and Q 2 (v), even for cases with a single detachment channel. Following Eq. ( 10), we define the experimental esti-385 mate of β as the expectation value of X [2] with respect 386 to the probability distribution (14) normalized by the 387 factor 1/N :

388 β = E[5P 2 (cos θ)] = 5 N ∞ 0 π 0 2π 0 dv dθ dφ v 2 sin θ ×P 2 (cos θ)P(v, θ, φ),
which yields

389 β = 1 N Q 2 (v)dv = Q 2 (v)dv Q 0 (v)dv . ( 15
)
In practice, the definition of the limits of the integrals 390 over v requires some prior information about the phys- closed. Such a solution only exists for a negative energy that must be found numerically by an iterative approach.

In the weak field regime considered here, the photodetachment cross section can be evaluated using perturbation theory: it is proportional to the modulus square of the dipole matrix element between the initial bound state of C -and a final continuum state of the neutral atom and an ejected photoelectron. This collisional wave function is determined at each photoelectron energy by matching at the boundary a the amplitude of the solutions of the inner and outer regions using the inverse log-derivative matrix. Full details of the R-matrix method are given in [START_REF] Burke | R-matrix Theory of Atomic Collisions: Ap-866 plication to Atomic[END_REF], in particular chapter 8 which treats photoionization.

In the spectral range covered by our experiment, we The challenge is to optimize a finite set of orthonormal orbitals while taking into account all these physical effects.

In Table III, we present the parameters of the ten Slater-type orbitals chosen to describe carbon in our Rmatrix calculations. The In Table IV [30].

487

The electron affinity of the carbon ground state is cal-

IV. RESULTS AND DISCUSSION

A. Total cross sections

The absolute cross sections for photodetachment of C -( 4 S o ) from our experiment are presented in Fig. 3 and compared with those by Seman and Branscomb [4] and Haeffler et al. [31]. Other data in the threshold region by Feldmann [6], Hall et al. [32] and Brandon et al. [33] are not reproduced here as they are not absolute and cover a very limited range of photon energies. Further discussion of their work can be found in the review by Andersen [2].

We first note that the cross section does not fall to zero below the photodetachment threshold of C -( 4 S o ), which indicates that some anions are produced in the 2 D excited state. Several control measurements from threshold to a photon energy of 2.7 eV were conducted using the VMI spectrometer to determine the branching ratio between each channel. We found that the branching ratio is almost constant at 2% throughout the controlled range, except around 1.38 eV, just above threshold, where it reaches at most 4%. As this quantity depends on both the population and the cross section of each state entering the beam composition, the problem is not experimentally constrained. We will address this in future work, but some insight can be gained from the theoretical study by Zhou et al. [34], which suggests that the cross section for photodetachment of C -( 2 D) is of a similar order of magnitude to that for photodetachment of C -( 4 S o ) over the energy range considered, with a small peak above the 4 S o photodetachment threshold. This in turn suggests that the population of C -( 2 D) in our anion beam is very small and that the measured cross sections are relatively unaffected by the presence of this state. Even in the worst case, near threshold, the estimate of the error obtained by combining the measured branching ratio and the theoretical cross section is of the order of 1.5%, 545 less than the experimental uncertainty.

546

Just above threshold, the cross section increases as 547 √ E, where E is the photoelectron energy, since the dom-548 inant channel is C(1s 2 2s 2 2p 2 3 P ) + e -(ℓ = 0). Beyond

575

We also note the very good agreement between our measurements using a continuous laser and using a pulsed laser taking into account the saturation effect, validating the developments leading to the correction coefficients of Fig. 2.

In Fig. 4, the current absolute cross sections for photodetachment of C -( 4 S o ) are compared with the results of our R-matrix calculation and those by Zhou et al. [7].

Other theoretical studies undertaken before 2004 [37][38][39] have been thoroughly discussed in [2,7], and since the agreement with experiment tends to be less good, they are not reproduced here. The differences between the cross sections obtained using the length and velocity representations of the dipole matrix are very small, less than 2% over the energy range considered, which is generally a good, but not sufficient, indication of the accuracy of a calculation.

The agreement between calculation and experiment is excellent over the whole range of energy covered by the experiment. The overall agreement with the results by Zhou et al. [7] is also very good. The main difference is in the region just above the first photodetachment threshold where our values for the total cross section, experimental and theoretical, increase monotonically, without the narrow peak due to a slightly larger contribution from the C(1s 2 2s 2 2p 2 3 P ) + e -(ℓ = 0) channel in the calculations of [7].

Since the objective of [7] was to study photodetachment from threshold up to 13 eV, only one orbital occurs at a slightly higher energy than in [7]. 729 FIG. 7. Asymmetry parameter β for the photodetachment of C( 4 S o ). Experiment: circles, present measurements; full square, Hall et al. [32]; open lozenge, Calabrese et al. [48]; open triangle down, Brandon et al. [33]. Theory: black full line: current R-matrix results, length form; red full line: current R-matrix results, velocity form; the thickness of the lines corresponds to the variation of results for different values of the calculation parameters, see text for details; dashed line: Zhou et al. [7], length form. Vertical dotted lines: positions of the C( 3 P ) and C( 5 S o ) thresholds.

V. CONCLUSION

  109measured with a Faraday cup.

  110

119

  stacked microchannel plates (MCP), a phosphor screen, a 120 metal-oxide semiconductor (CMOS) camera and a wave-121 form digitizer. 122 Data acquisition as well as fast digital control are 123 achieved using a field-programmable gate array (FPGA) 124 board while the whole setup is supervised by a LabVIEW 125 application. 126 B. Absolute cross section measurements 127 1. The ACB technique 128 The absolute measurement of the cross section is based 129 on the Animated Crossed Beam (ACB) technique [10], in 130 which the laser beam is periodically swept through the 131 perpendicular anion beam. The laser is characterized by 132 its frequency ω, pulse duration T p and, in a reference 133 frame whose origin is fixed at the beam intersection in 134 the center of the interaction zone, by the flux density 135 of photons φ p (x, y, z -Z, t) in the direction of propaga-136 tion. Z is the offset of the laser beam as it is swept 137 across the anion beam. The normalized photon flux den-138 sity, φ(x, y, z, t), is assumed to be constant from pulse to 139 pulse while the energy E p,Z may substantially vary for 140 each pulse p of the n Z laser shots (typically 120 for good 141 statistics) carried out at each offset Z: 142 φ p (x, y, z -Z, t) = E p,Z ω φ(x, y, z -Z, t). The C -anions, produced in a duoplasmatron source 143 with a bias potential -V S , have a nominal velocity v = 144 2eV S /M C -, where M C -is the mass of C -and e is 145 the elementary charge. At any instant during pulse p, 146 as the velocity v ≪ c, the laser illuminates an almost 147 static distribution of anions ρ(x, y, z, t), governed by the 148 equation 149 ∇ • j + ∂ρ ∂t = -σφρ, where j = ρ v is the anion current density and σ the pho-150 todetachment cross section. The solution of this equation 151

153

  factorized into a normalized distribution ρ(x, y, z) valid 154 for all pulses and a fluctuating magnitude related to the total current I p,Z = eρvdydz delivered by the source to the entrance of the interaction zone at the time of the laser shot: ρ(x, y, z; t p,Z ) = I p,Z ev ρ(x, y, z).

203

  the n Z laser pulses, taking into account the fluctuations 204 of energy shown in Fig. 2. 205 Unfortunately, assumptions concerning the beam pro-206 files are now unavoidable. Provided that the Rayleigh 207 length is greater than the diameter of the circular an-208 ion beam, which has a waist w 0 ∈ [250, 300] µm and 209 a pulse duration T p ∈ [7, 9] ns, we can expand the 210 laser profile about the coordinates of its maximum t M 211

polynomial and θ 1 .

 1 photoelectron cloud which, in the absence of aberrations, is independent of the location where photodetachment took place.Outside the lens, the velocity of the photoelectrons depends on the kinetic energy release (KER) of the photodetachment channel and on the bias potential applied to the repeller electrode. The photoelectrons therefore travel on expanding Newton spheres that are projected onto the detector screen. Assuming an azimuthal symmetry, it is possible to reconstruct from the 2D image the 3D angular distribution of the photoelectrons by an inverse Abel transform, for which many computational techniques are available. In this work, we use the MEVELER algorithm based on a Bayesian approach, developped in[22].

  272

274

  ibrate new detectors or to compensate for ageing, with an 275 accuracy of about one percent, depending on the number 276 of events. For the present experiment we have observed 277 a quite stable value of η = 95 ± 0.5% during the whole 278 process. To test the method, we have analysed the effi-279 ciency of another CEM detector, older and smaller, and 280 obtained a value of η = 90 ± 1%. 281 In ACB measurements with pulsed lasers, two or more 282 events detected during the same laser-neutral coincidence 283 time window will be counted as one. Under normal con-284 ditions, with a weak anion current and low photodetach-285 ment rates, the probability of such a counting loss is 286 small. We expect the number m p of neutrals effectively 287 produced in a pulse to follow Poisson statistics, charac-288 terized by a mean value m: 289 P[m p | m] = mmp m p ! exp(-m), and the number of detected neutrals m d to follow bino-290 mial statistics : 291 P[m d = y |η, m p ] = m p y η y (1 -η) mp-y . The value of m may be deduced from the total number 292 m T of counted neutrals for n pulses by noting that the 293 apparent rate per pulse m = m T /n ( m < 1) is the com-294 plement of the probability of no detection, yielding the 295 relation:

  the signal and the background n s times at each offset Z of the laser beam during the whole sweep time, rather than only at the beginning and at the end of each experimental run. With a switching delay T s leading to durations of direct and background measurements T m = T b = n s T s , during which m T and b T neutrals are respectively counted, the detection rate RZ entering Eq. (3) is estimated by RZ = Rm,Z -Rb,Z ; Var RZ = Rm,Z + Rb,Z n s T s , with Rm,Z = m T,Z /T m and Rb,Z = b T,Z /T b .

  335

  v 2 sin θ P(v, θ, φ) = 1, where p(v) is the radial velocity distribution normalized 343 so that p(v)dv = 1 and P ℓ is the Legendre polynomial 344 of degree ℓ. The coefficients β ℓ are then given by 345 β ℓ = (2ℓ + 1) dφ v 2 sin θ ×P ℓ (cos θ)P(v, θ, φ).(10)

391

  Photodetachment cross sections and asymmetry pa-412

  figuration interaction approach, for describing electron correlations in the inner region, delimited by the spatial extension of the most diffuse target state. The inner region therefore does not need to encompass the entire charge distribution of C -(1s 2 2s 2 2p 3 4 S o ). The orbitals must of course reproduce as accurately as possible not just the energy levels of the residual atom but also its electron affinity, which is very sensitive to the polarization of the target in the presence of the extra electron.

3 P

 3 and 5 S o configurations arising from the main configuration 1s 2 2s 2 2p 2 with excitation of up to two electrons from the n = 2 shell are included in the basis and the respective hamiltonian matrices are diagonalized. The spectroscopic 1s, 2s and 2p orbitals are Hartree-Fock orbitals[27]. The other orbitals are optimized using the CIVPOL computer code[28]: 3s, 3p, 3d and 4f are optimized on the ground state energy of C( 3 P ), 4s, 4p and 4d are optimized on the ground state polarizability.

488

  culated using the program STGB in the UK APAP suite 489 of codes[24]. This uses a perturbative treatment of the 490 long-range potentials in the R-matrix outer region combined with an iterative search over negative energies to find bound state solutions for the (N +1)-electron system.The value of the electron affinity will thus depend of the size of the R-matrix inner region and the number of continuum orbitals used (a larger inner region requires more continuum orbitals to ensure convergence). In addition, we found that it was necessary to include excitation of at least two electrons from the 1s 2 2s 2 2p 3 base configuration in order to obtain a bound state of C -. For the results reported below, we in fact included excitation of up to 3 electrons. For an inner region size varying between 25 a 0 and 35 a 0 and the number of continuum orbitals between 25 and 50, we obtained values of the electron affinity ranging from 1.2575 eV to 1.2613 eV, which compare favourably with the value of 1.2658 eV corresponding to the energy difference between the weighted average of the experimental fine structure levels of C( 3 P ) and the C -( 4 S o ) ground state [5]. The electron affinity in the calculation by Zhou et al. [7] is 1.21 eV.

549 1 eV

 1 , it increases slightly with photon energy before a 550 small dip in the vicinity of the C(1s 2 2s2p 3 5 S o ) thresh-551 old, followed by a steep increase due to the opening of 552 the C( 5 S o ) + e -(ℓ = 1) channel.

FIG. 3 .

 3 FIG. 3. Experimental cross sections for photodetachment of C -( 4 S o ) as a function of the photon energy. Full circle: present work with a pulsed laser and correction for saturation; open circles: present work with a pulsed laser without correction for saturation; full square: present work with a continuous laser. Error bars for the pulsed laser correspond to one standard deviation as estimated by expression (8). Open triangles: Seman and Branscomb [4]; crosses: Haeffler et al. [31]. Vertical dotted lines: positions of the C( 3 P ) and C( 5 S o ) thresholds.In the wake of their pioneering work on the photode-554

  Both calculations are completely ab initio, all coupled angular momenta are included and no energy shift was introduced. The radius a of the inner region is defined by the most diffuse atomic orbital, but as mentioned earlier, we have verified the stability of our results by performing calculations with different values of a from 25 a 0 to 35 a 0 , varying the number of continuum orbitals between 25 and 50, obtaining electron affinities between 1.2575 eV and 1.2613 eV. The cross sections resulting from these parametric tests are summarized in Fig. 4 by the thickness of the lines corresponding to the current R-matrix calculations. More precisely, two curves following the largest and smallest values of the calculated cross sections are plotted, and the area between them is shaded.

( 639 FIG. 5 .

 6395 FIG. 4. Experimental and theoretical photodetachment cross sections of C -( 4 S o ) as a function of the photon energy. Full circles: present work with a pulsed laser and correction for saturation. Black full line: R-matrix method, length form; red full line: R-matrix method, velocity form; the thickness of the lines corresponds to the variation of results for different values of the calculation parameters, see text for details. Dashed line: Zhou et al. [7], length form. Vertical dotted lines: positions of the C( 3 P ) and C( 5 S o ) thresholds.

  717

[ 33 ]

 33 is very good. The agreement with the R-matrix cal-718 culations is also excellent over the whole range of photon 719 energies considered. The small difference in the region 720 of the minimum at 2 eV with the calculation by Zhou et al. [7] reflects the differences at low energies in the ℓ = 0 722 and ℓ = 2 partial cross sections shown in Fig. 5. Above 723 the C(1s 2 2s2p 3 5 S o ) threshold, the ℓ = 1 channel gives 724 a constant contribution of β = 2, and is therefore not 725 shown in Fig. 7. As in the calculations by Zhou et al.

TABLE I .

 I Typical values for experimental uncertainties using the ACB technique.

	Uncertainties Type A (statistical):
	Detector efficiency	0.5 %
	Correction for saturation	1 %
	Statistical uncertainties with pulsed laser	2 %
	Statistical uncertainties with CW laser	0.5 %
	Combined uncertainties type A:
	Pulsed laser	2.3 %
	CW laser	0.7 %
	Uncertainties Type B (systematic):
	Powermeter / Energymeter	3.1 %
	Resolution	0.5 %
	Calibration	3 %
	Electrometer	1.1 %
	Resolution	0.5 %
	Calibration	1 %
	Vertical displacement Z	2 %
	Combined uncertainties type B:	3.8 %
	Final combined uncertainties:
	Pulsed Laser	4.5 %
	Continuous Laser	3.9 %

TABLE II .

 II Typical values for experimental uncertainties in the asymmetry parameters.

	Systematic errors:
	Circularization and Abel inversion	∆β = 0.01
	Background filtering	∆β = 0.01
	Statistical uncertainties:	∆β = 0.007

TABLE III .

 III Parameters of the ten Slater orbitals optimized on the energy and polarizability of the C(1s 2 2s 2 2p 2 3 P ) ground state using the computer code CIVPOL[28].

		C jnℓ I jnℓ	ζ jnℓ	C jnℓ I jnℓ	ζ jnℓ
	1s 23.64032 1 5.43599	2p 0.31061 2 0.98073
		4.04776 1 9.48256	1.58145 2 1.44361
		0.00110 2 1.05749	2.92085 2 2.60051
		-0.00583 2 1.52427	1.27982 2 6.51003
		0.07620 2 2.68435 0.15955 2 4.20096	3p 5.75621 2 1.55007
				-2.37862 3 1.36859
	2s -5.27596 1 5.43599 -0.62547 1 9.48256	4p 2.34572 2 0.51316
		0.10754 2 1.05749	-3.28476 3 0.68909
		2.48567 2 1.52427	1.03114 4 0.85291
		4.57346 2 2.68435 -6.16698 2 4.20096	3d 3.94743 3 1.89468
	3s	6.92570 1 2.34033	4d 2.78398 3 1.99721
		-20.83502 2 2.37260	-0.17968 4 1.07874
		2.68194 3 1.54022
	4s	3.86042 1 1.25514	4f 5.90852 4 2.41065
		-16.39226 2 1.23475
		17.35377 3 1.61817
		-0.05982 4 0.91968

TABLE IV .

 IV Energies of the 1s 2 2s 2 2p 2 3 P and 1s 2 2s2p 3 5 S o terms of carbon, together with those of the three polarized pseudostates included in the R-matrix calculations. The observed values are taken from the NIST Atomic Spectra Database[START_REF] Kramida | NIST ASD 874 Team[END_REF].

			Absolute	Relative Zhou et al. [7] Observed
			(a.u.)	(eV)	(eV)	(eV)
		3 P	-37.77831	0.0	0.0	0.0
		5 S o	-37.62867	4.07191	3.97679	4.17895
		3 P o	-37.40867	10.05842
		3 D o	-37.31503	12.60649
		3 S o	-37.26368	14.00380
		values from NIST and those of an earlier calculation by
	478
	479	combined with the Variable Phase Method (VPM) in the
	480	asymptotic region. The energy of the 5 S o level with re-
	481	spect to that of the ground state differs by 2.6% from
	482	the observed value and can be considered as sufficiently
	483	good for the purpose of this work. The full average polar-
	484	izability ᾱ of C(1s 2 2s 2 2p 2 3 P ) obtained by including 3 S o ,
	485 486	3 P o and 3 D o pseudostates is 11.58 a 3 0 , close to the value of 11.67 a 3 0 from an extensive coupled cluster calculation

477

Zhou et al.

[7]

, who used a similar R-matrix approach

ACKNOWLEDGMENTS

This work was supported by the Fonds de la Recherche 803 Scientifique-FNRS through IISN Contract No. 4.4504.10.


Frédérick Madore

Muslim Feminist, Media Sensation, and Religious Entrepreneur: Aminata Kane Koné as a Figure of Success in Côte d'Ivoire

This article analyzes the career path of Aminata Kane Koné, a highly educated Ivorian Muslim woman, who has emerged as a female figure of success. A prominent activist of the Association des Élèves et Étudiants Musulmans de Côte d'Ivoire in the 2000s, she has become a self-made religious entrepreneur through media and social initiatives. She has overcome social constraints to establish herself as a highly mediatized Muslim public intellectual, influential not only in Islamic circles, but within the broader society. Her case illustrates ways in which relationships between gender and Islamic authority are changing in West Africa. She embodies a uniquely hybrid feminism, influenced by her secular education and her Muslim faith.

Introduction

In Côte d'Ivoire, Islam has grown greatly since the 1950s. This religion accounted for around 20 percent of the population at the time of independence (Miran 2006, 61), but now accounts for 43 percent of the population, compared to 34 percent for Christians, according to 2014 census data [START_REF] Ibrahima | Recensement général de la population et de l'habitat 2014: Rapport d'exécution et présentation des principaux résultats[END_REF]. Researchers have shown considerable interest in Islam in predominantly Muslim countries in West Africa, but they have left Côte d'Ivoire relatively understudied. Nevertheless, a growing body of the literature has pointed out the diverse, changing, and contested Islamic field in Côte d'Ivoire, as illustrated by the rise of a modernist and reformist elite [START_REF] Miran | Islam, histoire et modernité en Côte d'Ivoire[END_REF], the recent dynamism of Salafism (Madore 2016a), and a Sufi revival (Binaté 2017a), with the participation of youth and women in neighborhood-based Islamic associations [START_REF] Leblanc | The Production of Islamic Identities through Knowledge Claims in Bouaké, Côte d'Ivoire[END_REF](LeBlanc , 2000(LeBlanc , 2007)). Since 2011, when Alassane Ouattara, the country's first Muslim president, was inaugurated, prominent imams and Muslim leaders of Abidjan have developed close relations with the ruling regime (Miran-Guyon 2017).

In recent years, several studies have highlighted the proliferation of locally initiated Islamic nongovernmental organizations (NGOs) [START_REF] Binaté | Muslim NGOs in Côte d'Ivoire: Towards an Islamic Culture of Charity[END_REF], including women-led ones (LeBlanc 2014(LeBlanc , 2016)), since the failed putsch of September 19, 2002, which divided Côte d'Ivoire into a southern region under the authority of President Laurent Gbagbo and a northern one controlled by insurgents. During the subsequent civil war, various humanitarian initiatives supported by international funding agencies filled the void left by crumbling state social services [START_REF] Akindès | Introduction: La transition humanitaire en Côte d'Ivoire, éléments de cadrage[END_REF]. Young Muslims in Côte d'Ivoire and elsewhere in West Africa are less engaged in Islamic activism than the 1990s generation while becoming more interested in personal fulfillment and ideas of religious entrepreneurship, which often involve humanitarian activities (LeBlanc 2012; [START_REF] Soares | Islam, jeunesse et trajectoires de mobilisation en Afrique de l'Ouest à l'ère néoliberale: Un regard anthropologique[END_REF].

While Marie Nathalie LeBlanc has focused on the entrepreneurship of "ordinary Muslims," mostly in Bouaké, 1 this article analyzes the career path of Aminata Kane Koné, a highly and secularly educated Ivorian Muslim woman in Abidjan, who has emerged as a female "figure of success" [START_REF] Banégas | Nouvelles figures de la réussite et du pouvoir[END_REF]. Over the last years, President Ouattara has repeatedly stressed the importance of fostering in Côte d'Ivoire an entrepreneurial culture for improving youth employment (Akindès 2017, 8-10); however, the youth, and especially women, still face a daunting labor market, despite impressive GDP growth since 2011 [START_REF] Lefeuvre | Insertion des jeunes sur le marché du travail en Côte d'Ivoire: La bombe à retardement est-elle dégoupillée?[END_REF]. Aminata Kane Koné, a prominent activist of the Association des Élèves et Étudiants Musulmans de Côte d'Ivoire (Association of Muslim Students of Côte d'Ivoire, or AEEMCI) in the 2000s, has become a self-made religious entrepreneur through media and social entrepreneurship. She has overcome social constraints to establish herself as a highly mediatized "Muslim public intellectual" (Soares 2016), influential not only in Islamic circles, but within the broader Ivorian society. She stands as a role model for many Muslim women aspiring to achieve her success. Her story exemplifies alternative trajectories for upward social mobility in African societies in a context where the possibilities are still constrained.

Much of the research on entrepreneurship in Africa has traditionally focused on the economic sector. In a context of dramatic socioeconomic changes following the imposition of structural-adjustment programs from the 1980s-deregulation, liberalization, privatization, currency devaluation, massive underemployment-several studies have examined new entrepreneurial strategies across the continent (e.g., Jalloh and Falola 2002). Some authors have analyzed African entrepreneurs in the development sector, where they act as brokers for international aid [START_REF] Bierschenk | Courtiers en développement: Les villages africains en quête de projets[END_REF], and in digital enterprises [START_REF] Taura | Digital Entrepreneurship in Sub-Saharan Africa: Challenges, Opportunities and Prospects[END_REF].

Increasingly, numerous publications investigate different forms of entrepreneurship beyond economic ventures. [START_REF] Banégas | Nouvelles figures de la réussite et du pouvoir[END_REF] have stressed the entrepreneurial abilities of Africans who have followed alternative paths to success through a moral economy of cunning and débrouille ("survival practices"). Other studies have focused on the "cultural entrepreneurs" active in media, education, culture, or religious sectors [START_REF] Röschenthaler | Introduction: Forging Fortunes; New Perspectives on Entrepreneurial Activities in Africa[END_REF].

Recently, interest in how religion and entrepreneurship intersect has increased [START_REF] Fourchard | Entreprises religieuses transnationales en Afrique de l'Ouest[END_REF], especially with the burgeoning of Pentecostal churches that preach the prosperity gospel [START_REF] Freeman | Pentecostalism and Development: Churches, NGOs and Social Change in Africa[END_REF][START_REF] Lauterbach | Religious Entrepreneurs in Ghana[END_REF][START_REF] Marshall | Political Spiritualities: The Pentecostal Revolution in Nigeria[END_REF]). Regarding Islam, Patrick Haenni (2005) has popularized the notion of religious entrepreneurship, as well as subsequent studies on Muslim entrepreneurs inscribing their business into the rhetoric of the "common good" [START_REF] Osella | Muslim Entrepreneurs in Public Life between India and the Gulf: Making Good and Doing Good[END_REF]. Several researchers have examined the Senegalese Murid trade diaspora (e.g., [START_REF] Diouf | The Senegalese Murid Trade Diaspora and the Making of a Vernacular Cosmopolitanism[END_REF]. Benjamin [START_REF] Soares | Islam and the Prayer Economy: History and Authority in a Malian Town[END_REF] has analyzed the "prayer economy" in Mali with the development of a "fee-for-service religion" by showing how Muslim saints have commodified their spiritual power. In another study, he has pointed out the rise of new religious entrepreneursmarabouts d'affaires-who cultivate an ethic of entrepreneurship in the era of neoliberal reforms (Soares 2017). Abdoulaye [START_REF] Sounaye | Alarama is All at Once: Preacher, Media 'Savvy', and Religious Entrepreneur in Niamey[END_REF]Sounaye ( , 2015)), studying the Nigerien case, has claimed that religious entrepreneurship has provided opportunities for young Muslims to acquire authority and build communities of followers by initiating projects to serve the community. Several women in Senegalese Sufi movements are becoming involved in development and entrepreneurial initiatives [START_REF] Hill | Charismatic Discipleship: A Sufi Woman and the Divine Mission of Development in Senegal[END_REF](Hill , 2018)).

In this article, I employ Ute Röschenthaler and Dorothea Schulz's definition of the "cultural entrepreneur" (2015, 1), which encompass religious and other kinds of entrepreneurship:

We use "entrepreneur" as a concept and a heuristic term to point to the plethora of engagements by which social actors in African societies deal with the constraints and opportunities generated by the contemporary moment. . . . The term "cultural entrepreneurs" refers to individuals who quickly perceive the chances of the moment and seize novel opportunities to initiate new forms of generating income in the realm of cultural production.

The rise of Aminata Kane Koné as a female figure of success occurred in a period of sociopolitical instability in Côte d'Ivoire but, at the same time, of opportunities with the development of Islamic and digital media. She is not a typical religious entrepreneur in the sense that she has not converted her economic resources into religious capital, nor accumulated great wealth through Islamic-related activities; instead, she exemplifies entrepreneurial innovation by branding herself through media and social initiatives. She cultivates the image of a young and pious Muslim public intellectual who demonstrates religious and entrepreneurial leadership.

Aminata Kane Koné's life trajectory illustrates the ways in which the relationships between gender and Islamic authority are changing in West Africa [START_REF] Frede | Introduction: En-Gendering Islamic Authority in West Africa[END_REF]; more specifically, it raises the issue of Islamic feminism, which has remained largely unexamined (e.g., Saint-Lary 2019, 243-69). Despite widespread resistance to the term feminism as connoting Western and secular women's activism, that does not necessarily mean Muslim women disagree with the idea that they should have the same political, social, and economic rights as men. For instance, Aminata Kane Koné positions herself as a feminist, even if she does not explicitly label herself as such. She embodies a hybrid feminism of her own, influenced by her secular educational background and her Muslim faith. As pointed out by Margot Badran, Islamic feminism and secular feminism are not "hermetic entities" (2009,[START_REF] Matin | Plume Libre and Islam Info[END_REF]. In a globalized world, Muslim women activists are likely to combine religious and secular frameworks to address rights and gender issues [START_REF] Hafez | An Islam of Her Own: Reconsidering Religion and Secularism in Women's Islamic Movements[END_REF][START_REF] Rinaldo | Mobilizing Piety: Islam and Feminism in Indonesia[END_REF][START_REF] Schielke | Second Thoughts about the Anthropology of Islam, or How to Make Sense of Grand Schemes in Everyday Life[END_REF]).

The article is based on empirical data collected in the course of fieldwork conducted in Abidjan during November 2014 and April 2015. The research included participant-observation and interviews with different cohorts of AEEMCI leaders and activists, men and women, including one lengthy interview with Aminata Kane [START_REF] Koné | Interview by the author[END_REF]. It draws on the national media 2 and the Islamic press, 3 as well as social media posts, interviews, and talks by Aminata Kane Koné posted online. The article begins by examining the role of women in the AEEMCI since its creation in the 1970s. If the association provided many young women with an opportunity to engage in activism alongside their male peers, AEEMCI programming tended to reproduce patriarchal power structures. The second part discusses how Aminata Kane Koné, who joined the AEEMCI in 1998, adopted a more radical approach to women's equality and emancipation within Islam than had her predecessors from the beginning of the 1990s. She has used Islam to empower other women and promote self-realization, financial independence, and professional opportunities for women. The third part analyzes her emergence as a media entrepreneur. Her activism caught the attention of management at the Islamic radio station Al Bayane, where she became a media sensation for more than ten years. Her ability to attract new followers as an opinion leader on social media contributed to her rise as a female Muslim public intellectual. The final section highlights how she gained attention from the US embassy in In the early 1970s, Francophone Muslim students educated in the école du Blanc-the Westernoriented public school system-began looking for ways to learn more about their religion and to reclaim their Islamic identity. Following the example of Christian students, they created informal Islamic groups at various educational institutions [START_REF] Fraternité Matin | Losséni Zoromé, président de la Jeunesse Estudiantine Musulmane[END_REF]. In January 1972, students at the Université de Cocody organized an assembly that led to the creation of the AEEMCI, the country's first national Muslim youth association, which was officially recognized by the state in April 1979. Although AEEMCI can be described as reformist or modernist, it is not formally aligned with a specific Islamic current. Members like to describe it as a melting pot, open to all Muslim students, regardless of the branch of Islam they follow [START_REF] Koné | Interview by the author[END_REF]. It focuses on explaining the tenets of Islam to students in French-language schools and universities.

The activities organized by the AEEMCI were adapted to an academic setting. They included evening classes, conferences, debates, seminars, film screenings, summer camps, Islamic cultural weeks, theater performances, and sporting events. In the 1970s and the 1980s, AEEMCI activists challenged negative stereotypes of Muslims. At the time, Ivorian media, as well as the country's secular and Christian elites, frequently portrayed Islam as a backward religion, dominated by superstitions. The AEEMCI responded by organizing conferences, debates, and talks that highlighted Muslim contributions to science, modernity, and economic development (Miran 2006, 295-346). Thanks to AEEMCI activities, Francophone Muslims began to be seen as legitimate interpreters of Islam. French emerged as a legitimate language for the development of Islam [START_REF] Miran-Guyon | Côte d'Ivoire, un Islam d'expression française à la fois tangible et restreint[END_REF].

Throughout the 1970s and 1980s, a notable number of girls participated in the religious educational activities organized by the AEEMCI. In addition to praying together, male and female students attended mixed-gender study sessions to deepen their Islamic knowledge. Such activities were often held in evenings, on weekends, or during school holidays. Nevertheless, the female members, despite their presence at various activities, played a decidedly marginal role in the organization during the period. This held true even in the case of activities focused on women's issues.

Consider the event held in December 1978 at the Williamsville Islamic Cultural Center in Abidjan. The female Muslim students of the Lycée Sainte-Marie had organized a dinner debate to discuss the place of Muslim girls in the modern world. A journalist assigned to cover the event applauded the organizers' initiative to discuss such a topical issue; however, the event proved disappointing: "the level of discussion, in the opinion of many, was not very impressive," and "the hostesses, too busy serving [food and drink], were not able to properly participate in the debate they themselves had organized" (Fraternité Matin 1978). 4 Both invited speakers-who discussed young Muslim women's clothing, marriage prospects, and professional opportunities-were men.

In the late 1980s, the AEEMCI male leaders tried to address the association's problems with engaging female members. The president of the association at the time has explained how young women themselves were pushing for change: "The girls demanded a more active role and refused to continue being treated as second-class activists" [START_REF] Doumbia | Interview by the author[END_REF]. The pressure for change led to the creation of Muslim Women's Days, a regular conference first held in 1987. That year's event focused on Muslim women's role in national development. The activity was modeled on the mixed-gender National Islamic Training Seminar, which had been held every summer since 1982; however, holding an event exclusively for female activists gave the women an opportunity to discuss their own issues without being drowned out by male voices. Meanwhile, the AEEMCI amended its statutes to reserve one of its three vice-presidential positions for a female member, who would be "in charge of women's affairs" [START_REF] Doumbia | Interview by the author[END_REF].

When the AEEMCI held Muslim Women's Days for the second time in 1989, its communication officer explained that the event would allow younger female activists to exchange ideas with their married elders. She emphasized the need to "give the floor to our sisters to tackle contemporary problems, . . . marriage, for example" (Fraternité Matin 1989a). Looking back on the event, the association's female vice president explained that it "should not be seen as a moment when sisters achieved autonomy in relation to their brothers, but simply as a time when all Muslim youth in Côte d'Ivoire sought to give women their rightful place in society, their proper attributes as defined in the Qur'an and the hadiths" (Fraternité Matin 1989b). In other words, the AEEMCI's female activists were not seeking to resist the patriarchal gender order or to reinterpret Islamic dogmas with the aim of reshaping gender relations; they largely accepted their assigned roles within the association. Their activities reflected a conscious desire to better conform to Islamic teachingsself-fashioning efforts to become "pious subjects" [START_REF] Mahmood | Politics of Piety: The Islamic Revival and the Feminist Subject[END_REF] 2011)-although these teachings tended to reinforce prevailing social norms. As several studies have pointed out, women's Islamic activism can contribute to reproducing dominant social norms without necessarily seeking to change them [START_REF] Augis | Dakar's Sunnite Women: The Politics of Person[END_REF][START_REF] Janson | Male Wives and Female Husbands: Reconfiguring Gender in the Tablighi Jamaʻat in The Gambia[END_REF]).

From the early 1990s, a growing number of female AEEMCI activists were not satisfied with closely following Islamic dogma and readily accepting dominant social norms. Instead, they relied on Qur'anic texts to defend their rights within Islam. In particular, this required better access to religious knowledge to distinguish accurately between "true" Islam and "traditional" Islam. Women were to become emancipated by struggling against ancestral customs and traditional practices that had not originated with Islam. Among the Dioula-Malinké community-the dominant Muslim group in Côte d'Ivoire-especially in the North and outside the cities, young teenage girls are usually taken out of school to help their mothers with domestic work or to be married. Most women depend economically on their husbands, and traditional models of womanhood are based on domesticity, motherhood, and obedience to male authority. Ethnocultural practices include familyarranged endogamous marriages, polygamy, female seclusion (purdah), and female genital mutilation [START_REF] Launay | Traders without Trade: Responses to Change in Two Dyula Communities[END_REF][START_REF] Leblanc | The Production of Islamic Identities through Knowledge Claims in Bouaké, Côte d'Ivoire[END_REF].

A proper application of Islamic precepts would allow Muslim women to emancipate themselves and enjoy their rights. As Badran (2009, 324-25) has explained, "It is not about the reforming of patriarchal claims and practices insinuated into Islam; it is rather about the transforming of what has passed as 'Islam' through a realignment of Islam with the Qur'anic message of human equality and social justice." Nevertheless, these activists did not challenge aspects of Islam itself or support the achievement of full gender equality. They primarily addressed gender relations in terms of gender complementarity and therefore acknowledged differences between men and women. They were careful to avoid conflicts with the AEEMCI's male activists. Maconi Cissé, one of the most visible and best-known Muslim women in Côte d'Ivoire during the 1990s, was a leading figure in this new cohort of female activists. In addition to teaching history and geography at the Lycée classique d'Abidjan, she presided over the Association des Femmes Musulmanes de la Riviera III (Association of Muslim women of the Riviera III), a particularly dynamic neighborhood-based Islamic association in a wealthy part of Abidjan. Her husband's brothers, Djiguiba Cissé and Alpha Cissé, are well-known Muslim figures. 5 Although she was not a member of the AEEMCI, she frequently spoke at women's activities organized by the association during the 1990s, including Muslim Women's Days, which is why she is considered today the "godmother of all generations of AEEMCI female activists." 6 Her reputation was strengthened by her appointment as the first vice president of the Conseil National Islamique (National Islamic council) responsible for women's affairs. In 1991, she helped establish the Association des Femmes Musulmanes de Côte d'Ivoire (Association of Muslim women of Côte d'Ivoire, or AFMCI), the country's first national women's Islamic association, which was officially recognized by the state in 1994 7 (Fraternité Matin 1997; Le Jour 1996).

In 1992, Maconi Cissé gave the closing address at the fourth edition of Muslim Women's Days, where she spoke about the concept of women's emancipation in Islam, identifying two main obstacles to women's emancipation: the weight of cultural traditions, which were un-Islamic, and the influence of Western modernity, which weakened moral standards. She insisted that "women's emancipation in Islam" should not involve a "frantic appeal for equality with men"; rather, she argued that although men and women have the same religious duties in Islam, Islam does not regard women as equal to men in all situations (La Voie 1992; Plume Libre 1992). These ideas were well aligned with those held by leading female figures within the AEEMCI. For example, in 1997, the association's vice president dismissed the caricature of Muslim women as perpetually oppressed by male authority by pointing out that Islam guarantees many rights for women; however, like Maconi Cissé, she nuanced her remarks by stating that "men and women do not have absolute equality. That would be absurd. What they do have is a rational and realistic equality based on different physical and biological attributes" (Le Jour 1997).

For Maconi Cissé, a wealthy and well-married woman, engaging in the 1990s in public activities about the proper role of Muslim women was a way to promote herself at the expense of other female activists. Following in her footsteps, Aminata Kane Koné emerged at the turn of the 2000s as a leading figure of a new cohort: younger female AEEMCI activists who adopted a more critical approach to ideas surrounding women's equality and emancipation in Islam.

Aminata Kane Koné and the Denunciation of "Bissap Activism": Islam as an Instrument of

Women's Emancipation

Born in 1981, Aminata Kane Koné was raised in a family of ten children actively involved in the local Muslim community. Her father, who died when she was six years old, contributed to the opening of several madrasas in the Adjamé district of Abidjan; her mother was a member of the management committee of their neighborhood mosque. Aminata Kane Koné joined the AEEMCI in 1998-the same year she began to wear the hijab-while she was a student at the Lycée scientifique de Yamoussoukro. By the following year, she had become president of the association's [START_REF] Cissé | Interview by the author[END_REF]. From 2008 to 2010, Aminata Kane Koné served as the AEEMCI's vice president responsible for social and women's affairs at the national level, the highest position a woman can hold in the organization. She received funding from the Spanish Agency for International Development Cooperation to complete a master's degree in 2012 in project development, with a focus on empowerment and leadership. She is currently pursuing a master's degree in neuroscience and aspires to be a professor.

In line with her self-described "rebellious nature" (Kane Koné 2015), Aminata Kane Koné notably helped institute major changes in the AEEMCI. Low participation by female activists at mixed-gender activities remained an issue at the turn of the twenty-first century. A women's-affairs officer with the organization blamed the problem on a "mental block" among female members:

"For them, speaking out or pondering big questions was men's business. They were content to simply prepare food and drink at activities" (Plume Libre 2001). For female activists, public display of modesty, religious humility, and deference to men were still the norm. Similarly to what LeBlanc was then observing in neighborhood-based Islamic association in Côte d'Ivoire, women "remained in a position of 'needing to be taught' the precepts of Islam and having their religious practice closely monitored by men who possessed formal religious training" (2014,183). Aminata Kane Koné's comments at the AEEMCI's National Islamic Training Seminar in 1998 took direct aim at the persistence of this patriarchal hierarchy within the association. Although it was the first time she had participated in the event, she was chosen to present the final resolutions adopted by female members. She declared that "we sisters no longer want to engage in bissap activism" (Kane Koné 2015), a reference to a popular juice made from dried hibiscus flowers. In other words, she was saying that the women of the AEEMCI were no longer satisfied with being relegated to kitchen duties. This colorfully expressed desire to find new roles for female activists and to defend their access to religious education provides a clear example of her feminism, even if she does not often use the term. While trying to be a pious subject by conforming to Islamic principles, she engages critically and publicly with religious texts and their interpretation to claim women's rights and equality much like proponents of feminism as defined by Miriam Cooke: "Feminism involves political and intellectual awareness of gender discrimination, a rejection of behaviors furthering such discrimination, and the advocacy of activist projects to end discrimination and to open opportunities for women to participate in public life" (2001, ix).

Unlike her predecessors, whose criticisms focused on cultural traditions, Aminata Kane Koné has openly challenged male Muslims' patriarchal interpretations of Islam, especially with the appeal of Salafism to an increasing number of Muslim university students since the mid-to late 1990s. In the next decade, doctrinal differences among AEEMCI activists on mixed-gender activities, wearing the niqab, and other issues led to dissent and the creation of new Muslim student organizations (Madore 2016a, 429-31). Aminata Kane Koné did not hesitate to take aim at the male members who were standing in the way of the changes she sought: People may well be religious and they may well be Muslims, but cultural and educational influences had led them to segregate women, to treat men differently, and to deny women a voice. Often, this approach is reflected in the behavior of certain brothers. They can only be described as macho.

. . . Because some of them had decided we were temptations for them, . . . they claimed they could no longer teach sisters. And since I was president at the time [2008][2009][2010], I said OK, we'll show these characters that we can also learn our religion without their help. . . . I don't see why I should have to worry about being a woman and not be able to learn my religion in the same way as a man. And the history of our religion teaches us that women have been at the forefront of many things. You need to avoid getting caught up in questions of gender. You need to stop telling yourself that there are things that you cannot do because you are a woman or that you do not have the right to do because you are a woman. (Kane [START_REF] Koné | Interview by the author[END_REF] The call to Muslim women to produce their own Islamic knowledge without relying on men and to perform as religious authorities for themselves even though they do not have formal training in Islamic jurisprudence, exegesis, or theology echoes Britta Frede and Joseph Hill's concept of "performativity" (2014). As they have argued regarding Muslim women, "Anyone perceived to know more than those in her or his milieu may potentially act as an authoritative personality in that context, even if the same person might not act as authoritatively in the company of scholars. Thus, people of all educational and social backgrounds can potentially demonstrate Islamic knowledge and act as an authoritative figure" (2014,152). When Aminata Kane Koné was in her senior year, with friends, she decided to assemble a women-only team for the Al Ilm 8 contest, a general-and Islamicknowledge trivia tournament organized by the AEEMCI. They wanted to show to male members that they could succeed on their own. They made it to the finals and won (Kane [START_REF] Koné | Interview by the author[END_REF].

For Aminata Kane Koné, expanding women's access to Islamic and secular education is fundamental, as many misconceptions persist about Muslim women who wear the veil, even if the number of veiled women on university campuses and in administrative offices has increased since the 1990s in Côte d'Ivoire (LeBlanc 2000). According to her, many people do not understand that a young woman could decide to "wear the veil for the sake of Allah" because the veil is often assimilated to being a "hadja," a nickname primarily given to older Muslim women who have made a pilgrimage to Mecca. 9 In a newspaper interview, she discussed the importance of knowledge for veiled women: I want to stress the importance of achieving a skill level that forces people to look beyond your veil. . . . The best way for a woman to distinguish herself is through the strength of her knowledge.

. . . Men will bow before your knowledge. Knowledge will ensure that you can get things done, that you will have money, that you will be a good wife, daughter, colleague. Knowledge is a woman's most precious possession. You can be extremely beautiful, but if you behave atrociously toward others, no one will notice your beauty. But your knowledge will open doors for you even if you are dressed in rags. (Islam Info 2018) In 2019, Aminata Kane Koné was invited to discuss feminism on an episode of Affaires de femmes (Women's Affairs), a series broadcast on the EDAN television network. During the debate, she explained that she "fully identified" with the definition put forward by Anglo-Irish author Rebecca West. She quoted her as saying, "I myself have never been able to find out what feminism is; I only know that people call me a feminist whenever I express sentiments that differentiate me from a doormat or a prostitute." Aminata Kane Koné added that, contrary to popular belief, the feminist struggle is not antithetical to wearing the veil: "As a veiled woman, . . . I have the right to express myself. I have the right to receive a quality education. I have the right to earn as many diplomas and degrees as I want, and to live my life as I see fit, while naturally taking my religious faith into account." In this regard, she stressed the importance of rejecting the "Western approach" that "we have imported from elsewhere," is "atheist," and "does not belong to us" (EDAN 2019).

From AEEMCI Activist to Islamic Radio Host and Media Entrepreneur

Aminata Kane Koné's talents as a public speaker, which she displayed at numerous women's activities organized by the AEEMCI, did not go unnoticed. Her experiences with the association served as a springboard for her career at Al Bayane, an Islamic radio station that began broadcasting in Abidjan and the surrounding area in November 2001, before expanding to other regions of Côte d'Ivoire. Today, it reaches more than 95 percent of the population and broadcasts twenty-four hours a day [START_REF] Cissé | [END_REF]. Since 2005, its signal has been streaming online. 10 Even if contemporary African mediascapes have been characterized by a proliferation of religious radio stations and TV channels [START_REF] Grätz | Contemporary African Mediascapes: New Actors, Genres and Communication Spaces[END_REF][START_REF] Hackett | Introduction: New Media and Religious Transformations in Africa[END_REF]Meyer and Moors 2006), Al Bayane has reached exceptional popularity in Côte d'Ivoire. In fact, according to a study conducted in 2018, it is the most popular radio station in the country, with more listeners than any other religious or secular radio station (Jeune Afrique 2019).

Fousséni Diabaté, Al Bayane's anchorman and a former member of the AEEMCI, recommended Aminata Kane Koné to the station manager because she had "the potential to be a good communicator" (Kane [START_REF] Koné | Interview by the author[END_REF]. Of late, the new media entrepreneurs who are emerging in Africa, many of them young people, often have no formal job training in communication and media production [START_REF] Grätz | Contemporary African Mediascapes: New Actors, Genres and Communication Spaces[END_REF](Grätz , 2013)). For instance, station manager Djiguiba Cissé and his team have pursued a strategy of recruiting young Muslims-both men and women-who do not necessarily have a background in journalism, communication, or even Islamic studies. Rather, these recruits have demonstrated eloquence and "good morals" by participating in activities organized by associations [START_REF] Cissé | [END_REF]. Islamic radio stations throughout sub-Saharan Africa have found that programs featuring discussions, debates, and public interactions-such as live talk shows hosted by young people, including women-tend to be popular in general and with younger listeners in particular [START_REF] Adama | Islamic Communication and Mass Media in Cameroon[END_REF][START_REF] Haron | Muslim Community Radio Stations: Constructing and Shaping Identities in a Democratic South Africa[END_REF]. Al Bayane has capitalized on this type of programing. Aminata Kane Koné, who was hired in 2007, seized the opportunity to become one of the station's most famous personalities. Between 2007 and 2016, she hosted various radio shows and played a key role in Al Bayane's development, especially by hosting live programs involving listener interaction, which were uncommon at the time she began to work at Al Bayane. Few programs were broadcast live to make it possible to review the content before airing it. This was particularly the case with programs featuring younger hosts who had not completed any advanced Islamic studies, and those hosted by women [START_REF] Savadogo | La médiatisation des prêches et ses enjeux: Regards croisés sur la situation à Abidjan et à Ouagadougou[END_REF]. Aminata Kane Koné cohosted a live show called Vie de femmes (Women's lives) 11 alongside Aïssata Diaby, 12 the program director. In it, they addressed women's rights; education; couple relationships; violence against women; economy, employment, and empowerment; and other women's issues. Aminata Kane Koné perceived her work at Al Bayane as a personal vocation in the continuity of her Islamic activism as a member of the AEEMCI. It gave her the opportunity to talk about how Islam is a helpful resource that can help women overcome everyday life challenges. Vie de femmes also allowed her to invite her listeners to rethink societal gender norms and popular misconceptions about women and Islam. She sought to raise awareness on the "real" status of women according to Islam, and more broadly, the question of women's role in society, since the audience is not composed exclusively of Muslims (Kane [START_REF] Koné | Interview by the author[END_REF]. By contrast, La matinale d'Al Bayane allowed Aminata Kane Koné to take part in current societal debates beyond issues related to Islam. The hosts and their guests discussed a multitude of topics, both religious and secular, including national and international current affairs, such as Islam and abortion, social media, homosexuality, food safety, and academic success factors. Aminata Kane Koné and Fousséni Diabaté maintained a close relationship with their audience, constantly encouraging listeners to join the conversation via telephone, text messages, or Facebook. At the radio station, they launched the Dédicace de l'internaute (Dedication of the internet user). Every Saturday, a presenter reads selected messages from the station's Facebook page, 13 which now has more than 208,000 followers. This interactivity greatly contributed to the program's success.

As a media-savvy entrepreneur, Aminata Kane Koné has cultivated a strong personal presence on the internet. Since the creation of her Facebook page in 2009, she has branded herself on social media reaching new publics. She has built an image of a young and pious Muslim public intellectual who has managed to conciliate her household responsibilities (She is the mother of eight children.) and work as a dental surgeon and a radio host-for which she is receiving much praise from her admirers, both male and female. Frequently asked about how she manages to do her professional work while raising such a large family, she has consistently stressed the value of effective time management, a frequent topic of her public talks. She emphasizes the importance of having an understanding husband-who is now the main imam of the Agitel-Formation mosque in Abidjan and the president of the Ruqya 14 Cell in Côte d'Ivoire-and the fact that all her sons regularly help with household tasks.

Over the years, Aminata Kane Koné has posted online several pictures of herself that regularly get a thousand "likes" and a hundred comments, often related to her beauty and her pious fashion. In response to her loyal following, she prepared a collection of her social media posts, organized by themes. As a result, her first book, Des mots pour apaiser (Words to appease), was published in 2017 by An-Nour World Space, a publishing house run by her husband. With more than 33,000 Facebook followers, 15 she is one of the few, or perhaps the only, Ivorian Muslim woman to have reached such popularity on the internet (Binaté 2017b;Madore 2016b). 16 When she announced her departure from Al Bayane on her Facebook page in March 2016, the news was greeted by 709 comments expressing both indignation and best wishes. In her message, she railed against her "unfair dismissal"-under the pretext of her double status as civil servant (dental surgeon at the UFHB) and journalist 17 -and took the opportunity to report certain issues with station management. 18 Besides her work experience at Al Bayane, Aminata Kane Koné has maintained an active media presence through various initiatives. She has been a member of the Union Nationale des Journalistes de Côte d'Ivoire (National Union of Journalists of Côte d'Ivoire) since 2015. She has been interviewed several times-on the Islamic TV show Allahou Akbar on the RTI channel, the public television provider, and even on various TV variety shows, such as C'midi (2015), 19 100% Femme (2018), 20 Affaires de Femmes (2019), 21 and La Télé d'Ici (2020). 22 Other than being a media entrepreneur, she has established herself as an activist for social causes beyond the religious sphere, especially the promotion of entrepreneurship among young women and men. we READ and then we PLAY). 24 The center aims to inspire a love of reading in young children while helping them overcome learning difficulties. In 2019, she left her volunteer position as an Ivorian ambassador for NH to become an NH bookseller. Among all her achievements, her invitation to the White House is probably the one that has contributed the most to her fame in Côte d'Ivoire. In 2010, to mark the fiftieth anniversary of many African countries gaining their independence, US President Barack Obama invited some one hundred young people, among whom was Aminata Kane Koné, to the President's Forum with Young African Leaders in Washington, DC. This meeting led to the creation of the Young African Leaders Initiative, designed to support "young African leaders as they work to spur growth and prosperity, strengthen democratic governance, and enhance peace and security across the continent" (The White House 2013). In an address to the invited leaders, President Obama personally congratulated Aminata Kane Koné for her advocacy work for Muslim women's rights, "rights that are sometimes denied by men" (Kane Koné 2015). In 2011, she was invited to Johannesburg, South Africa, to participate in the First Lady's Young African Women Leaders Forum, where she met Michelle Obama.

An Ivorian Success

When Aminata Kane Koné came back from the United States in 2010, she wanted to share her experience with as many young Ivorians as possible. Therefore, she founded the Facebook group "Young African Leaders Côte d'Ivoire" (YALCI). 25 YALCI was active mostly on social media before it became a formal organization in June 2013. Since then, she has presided over this network, which promotes leadership, entrepreneurship, and volunteerism among youth and encourages them "to play their part in the development of a new Africa" (Kane [START_REF] Koné | Interview by the author[END_REF]. YALCI has organized numerous debates on different themes related to young people's lives, such as the role of the youth for ensuring a peaceful presidential election in 2010, youth and national reconciliation following the postelectoral crisis, 26 journalism, corruption, HIV/AIDS, and reintegration of former combatants.

In addition to being regularly solicited by the US embassy as a moderator, speaker, and trainer in public speaking, Aminata Kane Koné is a frequent guest speaker for the AEEMCI, Aminata Kane Koné has contributed to raising issues she saw as important to women's emancipation, including self-realization, entrepreneurship, financial independence, professional opportunities, and the gender pay gap. In a televised debate in 2019, she stressed the importance of teaching young women to "avoid taking the easy road by telling themselves that, 'As a young woman, I simply need to make myself pretty, to be charming, and to catch the eye of a man who will marry me. Then, I'll enjoy an easy life at home'" (EDAN 2019). Although she has expressed admiration for women who choose to stay at home, she has nevertheless encouraged them to set aside some of their time for online learning, so they can find employment if they ever want or need to. In the same vein, she reminded her audience during a talk in 2018 that "the wife is responsible for taking care of her home," but "it is not a matter of saddling the wife with so many household responsibilities that she is deprived of any active role in society, and that society is deprived of her contributions." 28 By initiating all these entrepreneurial projects and activities, she has become an agent of religious, gender, and social transformations while becoming a female figure of success in the process.

Conclusion

Although Aminata Kane Koné does not represent the average of less privileged women in rural areas in Côte d'Ivoire, who cannot benefit from opportunities offered by urban life, her career path is remarkable in more than one respect. She has emerged as a female success story in a context where the possibilities for social climbing are usually constrained for young Muslim women. She has established herself as a successful religious entrepreneur active at the intersections of religion, media, and economic and social activities. Despite having no formal training in Islamic studies, she has claimed the right to teach and interpret Islamic texts based on her knowledge, charisma, pious image, and commitment to social issues. Aminata Kane Koné has contributed significantly to curtailing the male domination of religious leadership within the AEEMCI. Even though women were long involved in the AEEMCI, and it organized gender-based activities from its start, in the 1970s, female activists largely conformed to traditional religious teachings that maintained dominant social norms without seeking to change them. Things began to change in the 1990s, when some female activists started using Qur'anic texts to defend their rights in the face of local customs and traditions. From the moment Aminata Kane Koné joined the AEEMCI, in 1998, to the end of her mandate as the vice president responsible for social and women's affairs at the national level, in 2010, she renegotiated power relations within the Islamic organization. While striving to become a pious subject, she adopted a critical approach to religion in support of women's political, social, and economic rights from a feminist perspective. She exposed the inequities in sustaining a patriarchal interpretation of Islamic texts and did not hesitate to defy misogynistic AEEMCI's male activists openly. She stressed the importance of Muslim women producing their own Islamic knowledge and strongly advocated for women's self-realization, entrepreneurship, and financial independence.

Her Islamic activism allowed her to launch a career as a media entrepreneur. The managers of the Islamic radio station Al Bayane had started to recruit more young people and, in some cases, women, who made up for their lack of formal training in communication and Islamic studies with a high degree of eloquence and charisma. Hired in 2007, she established herself as one of the most famous Islamic radio presenters by hosting live talk shows. She has become much admired for her views expressed on Islam and women, as well as on nonreligious topics. Her engagement with social media has played a key role in the making of her career. By using Facebook actively, she mobilized a growing community of followers and sympathizers, both women and men. She has distinguished herself as an entrepreneur by launching initiatives related to women's rights and youth

  Côte d'Ivoire while pursuing various social projects. The symbolic and financial recognition she received from the American government for her advocacy work for Muslim women's rights and youth entrepreneurship has reinforced her image as a female figure of success. Limited Role for Women in the AEEMCI (1970-2000): Preparing Food and Drink for Attendees?

  women's section in this institution. After obtaining her baccalaureate degree in 2000, she attended the Université d'Abobo-Adjamé in Abidjan and was appointed president of the AEEMCI's women's section of the university. Her marriage in 2001 with Bakary Koné, the AEEMCI's national vice president between 2000 and 2003, and the birth of her first child did not prevent her from continuing her studies. She went on to study in the Faculty of Odonto-stomatology at the Université Félix Houphouët-Boigny (UFHB), graduating as a qualified dental surgeon in 2013, when she earned her PhD. Although she did not hold a leadership position in the AEEMCI between 2000 and 2008, she frequently spoke at the association's conferences, seminars, and other activities in a period when Muslims were suffering numerous abuses. From the 2000 presidential elections (especially after the failed coup of September 2002) to the signing of the Ouagadougou agreement in 2007, government security forces targeted suspected rebel sympathizers, including Muslims. Mosques were raided, Muslim leaders arbitrarily arrested, and several imams assassinated (Miran-Guyon 2015). Members of the Fédération Estudiantine et Scolaire de Côte d'Ivoire (Student federation of Côte d'Ivoire) and other progovernment youth groups, such as the Jeunes Patriotes (Young patriots), perpetrated violence against Muslim students groups. In July 2002, the AEEMCI president survived an attempted murder

For

  several years, Aminata Kane Koné cohosted La matinale d'Al Bayane (The Al Bayane Morning Show), a highly popular live talk show, alongside Fousséni Diabaté. Even if an increasing number of women are hosting (live) programs on Islamic radio stations in West Africa (Gomez-Perez 2016; Gomez-Perez and Ba 2015; Madore and Gomez-Perez 2016; Ndzovu 2019; Schulz 2012), most of them are usually preachers who address themes strictly related to Islam and women.

  Story at the White House: Aminata Kane Koné's Advocacy Work for Youth Entrepreneurship "Doing good," overcoming social injustices, and promoting the good values of Islam have been the major aims of Aminata Kane Koné's entrepreneurial activities in recent years. She has been heavily involved in several projects promoting women's rights, Muslim and non-Muslim, as well as other initiatives related to education and employment. Collaborating with seven NGOs and associations, she initiated a project to support the adoption of a charter of good conduct regarding sexual violence and abuse against girls in schools (Kane Koné 2015). Her expanding professional network with United States representatives in Côte d'Ivoire and abroad has opened new opportunities for her. The American embassy in Côte d'Ivoire has taken note of her social-engagement and volunteer work. In 2010, she was named Ivorian ambassador for Nouveaux Horizons (NH), a publishing house run by the Africa Regional Services of the US State Department. The NH imprint publishes books by American authors translated into French for sale and distribution in francophone Africa, the Maghreb, and Haiti. 23 To be selected, candidates must have shown a proven commitment to their community through volunteering or mentoring for children, youth, women, or other segments of the population. In 2018, in partnership with NH, Aminata Kane Koné opened a children's reading center called Ici on LIT ensuite on JOUE (Here

  especially since its activists have been showing increased interest in entrepreneurship and socioeconomic development. In recent years, as with other Islamic associations, many AEEMCI activities have dealt with Muslims and "An emerging Côte d'Ivoire looks forward to 2020," a slogan 27 regularly used by President Ouattara. Youth and women figured prominently in his Plan National de Développement (National development plan). For example, in 2016, the theme for the AEEMCI Female Activists' Day was "Leadership and Entrepreneurship among Women: Benefits for a Society Working toward Emergence." Participants had the chance to attend two training workshops: "Female Excellence in Support of Emergence" and "How to Launch a Business Project" (Islam Info 2016). In 2017, Aminata Kane Koné was the keynote speaker at the twelfth AEEMCI Female Activists' Day for a talk on a similar topic.

  entrepreneurship. The support and praise she has received from US authorities have further consolidated her position as a leading female Muslim public intellectual in Côte d'Ivoire and as a role model for Muslim women and young Ivorians.Through her actions and entrepreneurship, Aminata Kane Koné has claimed a meaningful Islamic identity, capable of contributing to the ongoing transformation of religious practices and the socioeconomic development of her country. Her career path seriously undermines the image of Muslim women perceived as passive, oppressed, and "in need of saving" (Abu-Lughod 2013), often propagated by the rhetoric of salvation in some Western media and human-rights discourses. Islamic piety can be compatible with the ideas of women's rights and equality. Her case highlights how Muslim women in sub-Saharan Africa are too often overlooked in research on Islam and feminism.

Acknowledgments

I thank the three reviewers for their insightful comments, and Yssoufou Traoré for his assistance during the fieldwork. This article is based on research funded by a Joseph-Armand Bombardier Canada Graduate Scholarships Program Doctoral Scholarship and a Banting Postdoctoral Fellowship (Social Sciences and Humanities Research Council of Canada).