Two-photon emission of a 2p electron from Ne+and consequences for sequential double ionization of Ne

Using the R -matrix Floquet approach, we investigate two-photon emission of a 2p electron from the 1s 2 2s 2 2p 5 ground-state of Ne + irradiated by laser light with photon energies between 25 eV and 40 eV and an intensity of 10 14 W cm −2 . We obtain 2p emission rates for Ne + initially in the M = 0 and M = 1 levels. Two-photon emission of the 2p electron from the M = 0 level leaves Ne 2+ predominantly in 2p 4 1 D e , whereas two-photon emission of the 2p electron from the M = 1 level leaves Ne 2+ predominantly in 2p 4 3 P e . In sequential double ionization of Ne, the first ionization step thus has a noticeable influence on the second ionization step. The present rates differ significantly from ionization rates deduced from experiment. The main reason for this is probably that two-photon emission of a 2s electron is the dominant ionization process at 38.4 eV.