The B-spline R-matrix method applied to photoionization of neon

We present calculations for the total photoionization cross section of neon from its ground state using the B-spline R-matrix (BSR) method within the LS-coupling framework. A sophisticated 38-state target model, originally developed for time-delay studies [1], is used to carry out the full calculation, while subsets of this model are used to study the convergence of the predicted photoionization cross section, in particular the resonance structure, with respect to both the completeness of the Ne⁺ basis set and the form of the dipole operator. The calculated total photoionization cross section is in excellent agreement with experiment [2] over the broad photon energy range above the first ionization threshold, from 21.6 eV to 125 eV. We also present results for select features in the series of resonances that are encountered in the energy range of 1.60 Ry − 2.53 Ry above the Ne⁺ ground state. In particular, we present calculations for the 2.32 Ry − 2.49 Ry energy range, which contains several overlapping Rydberg series. Throughout, we demonstrate the role that additional target states play in the predicted photoionization cross sections, especially within the resonance region.

[1] J. Feist et al., Phys. Rev. A 89 (2014) 033417.

[2] J. A. R. Samson and W.C. Stolte, J. Elect. Spect. Relat. Phenom. 123 (2002) 265.