Ejected-Electron Angular Distribution in Multi-Photon Ionization of Atomic Hydrogen by Ultrashort High-Intensity Laser Pulses

Advisor: Klaus BartschatWe have studied the multi-photon ionization of atomic hydrogen by an intense attosecond laser pulse. We numerically integrate the time-dependent Schrodinger equation by propagating the initial H(1s) state after the onset of the laser pulse using the Crank-Nicolson algorithm. When the pulse is over, we extract the angular distribution of the ejected electrons from the time-propagated wavefunction. For few-cycle 800 nm laser pulses of peak intensities ranging between 1013 and 1015 W/cm2, the photoelectron spectrum is dominated by a set of above-threshold resonances, with the lowest resonance around 0.35 eV corresponding to the nine-photon ionization of the hydrogen atom. In contrast to the standard single-photon ionization process, where the angular distribution is a simple cos2(0) function, many more anisotropy parameters need to be accounted for to describe the ejected photo-electrons. Corresponding experiments are currently being performed in Brisbane (Australia) on hydrogen and Heidelberg (Germany) on Li. Where possible, comparison with experimental data will be made.Drake University, College of Arts and Sciences, Department of Physics and Astronomy ; Institute of Nuclear Physics, Moscow State Universit