No abstract

We present R-Matrix with time dependence (RMT) calculations for the photoionization of helium irradiated by an EUV laser pulse and an overlapping IR pulse with an emphasis on the anisotropy parameters of the sidebands generated by the dressing laser field. We investigate how these parameters depend on the amount of atomic structure included in the theoretical model for two-photon ionization. To verify the accuracy of the RMT approach, our theoretical results are compared with experiment.PACS numbers: 31.15.A-,32.80.Rm

We apply time-dependent R-matrix theory to study inner-shell ionization of C atoms in ultrashort highfrequency light fields with a photon energy between 170 and 245 eV. At an intensity of 10 17 W/cm 2 , ionization is dominated by single-photon emission of a 2 electron, with two-photon emission of a 1s electron accounting for about 2-3% of all emission processes, and two-photon emission of 2 contributing about 0.5-1%. Three-photon emission of a 1s electron is estimated to contribute about 0.01-0.03%. Around a photon energy of 225 eV, two-photon emission of a 1s electron, leaving C + in either 1s2s2p 3 or 1s2p 4 , is resonantly enhanced by intermediate 1s2s 2 2p 3 states. The results demonstrate the capability of time-dependent R-matrix theory to describe inner-shell ionization processes including rearrangement of the outer electrons.

No abstract