Theoretical studies on tunneling ionizations of helium atom in intense laser fields
Journal
Journal of Chemical Physics
Journal Volume
124
Journal Issue
14
Date Issued
2006
Author(s)
Abstract
Our generalized Keldysh theory is applied to the simplest many-electron atom, helium atom. For the single ionization (He→He++e) we derive a compact rate formula, which does not contain any series summation or integral and thus is as simple as the Ammosov-Delone-Krainov ionization rates. In addition to its simplicity, our formula can explicitly show the wavelength dependence. Furthermore a simple form of the angular distribution of the photoelectron is available. Our compact formula agrees well with both the exact numerical calculations [A. Scrinzi et al., Phys. Rev. Lett. 83, 706 (1999)] and experimental data [B. Walker et al., Phys. Rev. Lett. 73, 1227 (1994)] in the intensity range of I<5×1015W∕cm2. In higher intensity regions, we suggest to utilize another simple formula which is valid in the tunneling limit.
Type
journal article