Ionization widths for Ne(3l)-Ar systems(l=s,p): Application to ionization and intramultiplet mixing cross sections

Ab initio autoionization widths for the Ne$\mathrm{}\left(3s\right)\mathrm{}$-Ar and Ne$\mathrm{}\left(3p\right)\mathrm{}$-Ar systems are calculated in a two-electron approximation. Using correctly normalized wave functions, the calculations result in absolute values for the autoionization widths. We use a modified coupled-channel code with ab initio potentials and ionization widths as input to calculate cross sections for ionization and intramultiplet mixing. The influence of ionization on the intramultiplet mixing process can thus be studied. Experimental results for intramultiplet mixing cross sections for the Ne$\mathrm{}\left(3p\right)\mathrm{}$-Ar system at a collision energy $〈E〉=1.7\mathrm{}$ eV are presented. These data and ionization cross sections obtained by Bussert et al. [Z. Phys. A 320, 105 (1985)] are in good agreement with coupled-channel calculations. For the Ne$\mathrm{}\left(3s\right)\mathrm{}$-Ar system the calculated ionization widths are in good agreement with empirical ionization widths derived in a multiproperty analysis of a wide range of scattering data. For this system we have to conclude that the ab initio results cannot explain the experimental cross section ratio ${Q(}^3{P}_0{)/Q(}^3{P}_2)$=1.3. Therefore, ab initio calculations of the real part of the potential are essential for a correct quantum-mechanical coupled-channel analysis.