Above-threshold ionization of hydrogen and hydrogen-like ions by X-ray pulses

• Published in: Central European journal of physics Vol. 11; no. 9; pp. 1091 - 1098
• Main Authors: Bachau, Henri, Budriga, Olimpia, Dondera, Mihai, Florescu, Viorica
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.09.2013; Versita; De Gruyter
• Subjects: Above threshold ionization; Biological and Medical Physics; Biophysics; Environmental Physics; Geophysics/Geodesy; Hydrogen; hydrogenic ions; Multiphoton ionization; Physical Chemistry; Physics; Physics and Astronomy; Research Article; X-ray; Above threshold ionization; hydrogenic ions; X-ray; Hydrogen; Multiphoton ionization
• ISSN: 1895-1082; 2391-5471; 1644-3608; 2391-5471
• DOI: 10.2478/s11534-012-0140-x

This paper adresses the problem of above-threshold ionization (ATI) of hydrogen interacting with an intense X-ray electromagnetic field. Two approaches have been used. In the first approach, we calculate generalized differential and total cross sections based on second-order perturbation theory for the electron interaction with a monochromatic plane wave, with the A 2 and A · P contributions from the nonrelativistic Hamiltonian (including retardation) treated exactly. In the second approach, we solve the time-dependent Schrödinger equation (TDSE) for a pulsed plane wave using a spectral approach with a basis of oneelectron orbitals, calculated with L 2 -integrable B -spline functions for the radial coordinate and spherical harmonics Y lm for the angular part. Retardation effects are included up to O (1/ c ), they induce extra terms forcing the resolution of the TDSE in a three dimensional space. Relativistic effects [of O (1/ c 2 )] are fully neglected. The isoelectronic series of hydrogen is explored in the range Z = 1 − 5 in both TDSE and perturbative approaches. Photoelectron angular distributions are obtained for photon energies of 1 keV and 3 keV for hydrogen, and photon energy of 25 keV for the hydrogenic ion B 4+ . Perturbative and TDSE calculations are compared.