Eur. Phys. J. D 59, 193-200 (2010)
https://doi.org/10.1140/epjd/e2010-00135-3

Ionization of the hydrogen atom by short half-cycle pulses: dependence on the pulse duration

¹ Institute for Astronomy and Space Physics, IAFE, CC 67, Suc. 28 (1428), Buenos Aires, Argentina
² Department of Physics, FCEN, University of Buenos Aires, Aires, Argentina
³ Department of Physical Science and Applications, Hellenic Army Academy, Vari, Greece
⁴ Department of Informatics, Technological Educational Institution, Lamia, Greece
⁵ Institute of Theoretical and Chemical Physics, National Hellenic Research Foundation, Athens, Greece
⁶ Institute of Nuclear Research of the Hungarian Academy of Science, ATOMKI, PO Box 51, 4001 Debrecen, Hungary
⁷ Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Romania

Corresponding author: ^a tokesi@atomki.hu

Received: 30 December 2009
Revised: 1 April 2010
Published online: 12 May 2010

Abstract

A theoretical study of the ionization of hydrogen atoms by short external half-cycle pulses (HCPs) as a function of the pulse duration, using different quantum and classical approaches, is presented. Total ionization probability and energy distributions of ejected electrons are calculated in the framework of the singly-distorted Coulomb-Volkov (SDCV) and the doubly-distorted Coulomb-Volkov (DDCV) approximations. We also performed quasiclassical calculations based on a classical trajectory Monte Carlo method which includes the possibility of tunneling (CTMC-T). Quantum and classical results are compared to the numerical solution of the time-dependent Schrödinger equation (TDSE). We find that for high momentum transfers the DDCV shows an improvement compared to the SDCV, especially in the low-energy region of the electron emission spectra, where SDCV fails. In addition, DDCV reproduces successfully the TDSE electron energy distributions at weak momentum transfers. CTMC-T results reveal the importance of tunneling in the ionization process for relative long pulses and strong momentum transfers but fails to overcome the well-known classical suppression observed for weak electric fields.