Alignment dependence of high-order harmonic generation from N2 and O2 molecules in intense laser fields

Abstract

The strong field approximation is used to investigate the harmonic generation of aligned N2 and O2 molecules. It is shown that the angular dependence of the yields of high-order harmonic generation from N2 and O2 molecules are different, which can be attributed to the orbital symmetry of the outmost electrons. The theory is applied to study the angular dependence of harmonic generation from recent pump-probe experiments where the pump pulse was used to produce the time-dependent partial alignment of molecules and the probe pulse was used to generate high-order harmonics. Good agreement with the experiments was found.