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

D.G. ARBÓ; M.S GRAVIELLE; K. I. DIMITRIOU; K. TÖKÉSI; S. BORBÉLY; J.E. MIRAGLIA

EUROPEAN PHYSICAL JOURNAL D

Springer-Verlag

Lugar: Leipzig; Año: 2010 vol. 59 p. 193 - 200

1434-6060

A theoretical study of the ionization of hydrogen atoms by short externalhalf-cycle pulses (HCPs) as a function of the pulse duration, using different quantum and classical approaches is~presented. Total ionizationprobability and energy distributions of ejected electrons are calculated inthe framework of the singly-distorted Coulomb-Volkov (SDCV) and thedoubly-distorted Coulomb-Volkov (DDCV) approximations. We also performed quasi-classical 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 exact solution of the time-dependent Schrödinger equation (TDSE). We show 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.