A general algorithm for fitting efficiently triple differential cross sections of atomic double photoionization

Abstract

We propose an effective procedure to fit triple differential cross sections of atomic double photoionization processes, which is based on a general expression of the transition amplitude between arbitrary states of the target atom and the parent ion, with the transition operator expressed at any order of its multipolar expansion. The major advantage of our expression, which in the dipole approximation is equivalent to those of Manakov (1996 J. Phys. B: At. Mol. Opt. Phys. 29 2711) and Malegat (1997 J. Phys. B: At. Mol. Opt. Phys. 30 251), is that it is expressed only in terms of elementary angular functions (Clebsch–Gordan coefficients, spherical harmonics and 6 − j factors). Therefore our expression can be easily implemented in a general code for any kinematic condition and any order of the multipolar expansion of the transition operator. Our fitting procedure takes into account also the finite instrumental resolution in measuring energies and angles. Test calculations on helium and argon show that this further capability is often essential to remove important discrepancies between simulated and measured angular distributions.

Fully Differential Single-Photon Double Ionization of Neon and Argon

“…[1][2][3][4][5], and references therein). In contrast, for heavier rare-gas atoms, the volume of experimental measurements of one-photon DPI greatly outweighs the theoretical data, which have been confined to model treatments [6] and parameterization of the process [7,8]. At the same time, significant interest in studying rare-gas targets in laser-atom interactions has evolved beyond the single-photon perturbative limit of DPI.…”