Energy and momentum spectra of photoelectrons under conditions of ionization by strong laser radiation (the case of elliptic polarization)

Analytical and numerical studies are made into the momentum distribution an d energy spectra of photoelectrons emitted during nonlinear ionization of a toms and molecules by laser radiation with elliptic polarization. The depen dence of these distributions on the ellipticity xi of an electromagnetic wa ve is treated, as well as their evolution upon variation of the Keldysh par ameter gamma from the region of optical tunneling (gamma << 1) to the regio n of gamma >> 1, in which the ionization is multiphoton. The quasiclassical approximation is used in the calculations, in particular, the imaginary-ti me method and the saddle-point method with expansion in the vicinity of the field ellipse. (C) 2001 MAIK "Nauka/Interperiodica".