On the Theory of Hydrogen Atom Ionization by Ultra-Short Electromagnetic Pulses

An investigation of the probability of hydrogen atom ionization by ultra-short electromagnetic pulses is carried out in the frame of perturbation theory We consider the case when the electric field strength amplitude E0 in a pulse by two orders lower than characteristic atomic field strength E-a(E-a congruent to 5.1.10(9) V/cm). A detailed investigation of the dependence of the probabilities on the pulse duration was performed for Gaussian pulse shapes. In the case where the carrier frequency of the Gaussian pulse is larger than the atomic ionization potential, the probability goes to the standard limit of perturbation per unit time. At the same pulse durations, the probabilities for carrier frequencies less than the ionization potential go to zero. The frequency dependence of the ionization probability becomes equal to the standard threshold dependence with increasing pulse duration time. A comparison between the ionization effects caused by wavelet pulses without carrier frequency and Gaussian pulses with carrier frequency shows that the same ionization probability values are achieved when the pulse carrier frequency is detuned by about 20% from the ionization threshold. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim