Effect of the R dependence of laser-induced polarizability on molecular dynamic alignment in an intense femtosecond laser field

Abstract

In the rotation equation of the angle θ between the molecular axis and the laser polarization direction, the dependence of laser-induced polarizability on the molecular internuclear distance R is considered. The effect of the R dependence of laser-induced polarizability on molecular dynamic alignment in an intense femtosecond laser field is investigated with 20 and 100 fs laser pulses for N2 molecules and with 60 and 100 fs laser pulses for Br2 molecules at intensities of 5×1014 W cm−2 and 5×1015 W cm−2. This effect exists and only occurs during the dissociative process after the molecule is ionized. It enhances the degrees of molecular dynamic alignment and is more significant in reorienting the angular distributions of molecules towards the laser polarization direction in the conditions of high laser intensity and short pulse length. Compared with the N2 molecule, the effect of the R dependence of laser-induced polarizability on molecular dynamic alignment for Br2 is stronger. The reasons are presented and discussed.