Krypton 4p, 4s, and 3dpartial photoionization cross sections below a photon energy of 260 eV

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Abstract
The photoionization of krypton 4p, 4s, and 3d subshells has been studied theoretically from the 4p threshold and experimentally from the 3d threshold up to a photon energy of 260 eV. In converting the measured count rates of the 4p, 4s, and 3d main photoelectron lines into partial cross sections, we have used recent photoion yield measurements to estimate the contribution of multiple-excitation processes to the total photoabsorption cross section. Theoretical partial cross sections and angular asymmetry parameters have been calculated using the multichannel Dirac-Fock method. Eighteen leading single-excitation channels related to the 4p, 4s, 3d, and 3p hole configurations of the final ionic state were included. Relaxation was taken into account by using separately optimized initial- and final-state orbitals and by including all the resulting overlap integrals in the transition amplitudes. The relaxation effect was found to depend strongly on the photon energy in the near-threshold regions. For the 3d subshell the relaxation reduces the 3d cross section by 35–40 % at the maximum, whereas it is less significant for the 4p and 4s cross sections.