Nondipole effects in the photoionization of neon: Random-phase approximation

The random-phase approximation (RPA) is applied to study nondipole corrections to the angular distribution of photoelectrons from the $n=2$ shell of Ne. Calculations of the parameters ${\ensuremath{\gamma}}_{\mathrm{nl}}$ and ${\ensuremath{\delta}}_{\mathrm{nl}}$ arising from ${E}_{1}\ensuremath{-}{E}_{2}$ interference effects are carried out for the $2s$ and $2p$ subshells of Ne in the photon energy range 100--2000 eV. For the $2s$ shell, the RPA calculations show small effects of correlation near the $2s$ threshold energy, but are otherwise in agreement with independent-particle approximation (IPA) calculations. The RPA and IPA values of ${\ensuremath{\gamma}}_{2s}$ are also in agreement with experiment. For the $2p$ shell, a small difference between RPA and IPA calculations of the nondipole parameters is found for energies near the $1s$ threshold; however, both RPA and IPA calculations of the parameter ${\ensuremath{\gamma}}_{2p}+3{\ensuremath{\delta}}_{2p}$ disagree significantly with experimental measurements for photon energies above 1000 eV.

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