Improved treatment of the turning point in tunnel ionization of atoms in a low-frequency two color laser field

Abstract

The tunneling photoionization rate for a two color (bichromatic) field consisting of coherent superposition of the fundamental laser field frequency and its second harmonic with frequency 2, was studied theoretically within the framework of the adiabatic Landau–Dykhne approach. Analytical expressions were derived for the case of fixed specified values of relative phase shift, between the harmonics of the incident bichromatic field.