engleski

O(1/omega) corrections to the shake-off (shake-up) correlation effects in double (single) ionization of He by absorption of a photon

We investigate cross sections for double and single ionization of He from its ground state, integrated over angles, by absorption of a single photon at photon energies omega much larger than the ionization energy for the process. Using a generalized asymptotic Fourier transform approach we obtain the corrections of order m alpha^2/omega, relative to the previously obtained shake results, for the spectrum of double ionization when one electron has very small energy, and for the total cross sections for single ionization when one electron stays bound in a shell n. We find that the dominant contributions to these corrections come from the final state interaction, in all cases considered, except when one electron stays bound in the ground state, in which case the correction is relatively small. We find very good agreement with experiment and with ab initio calculations. We also discuss recent model calculations which neglect some of the corrections which we obtain.

photoabsorption; correlations; double ionization; helium

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