Rotational dynamics of neutral O₂ driven by linearly, elliptically and circularly polarized femtosecond pulsed lasers

Abstract Rotational dynamics simulations of neutral O 2 molecules driven by linearly, elliptically and circularly polarized femtosecond pulsed lasers are carried out using a full quantum time-dependent wave packet evolution method. Here, the direction of laser propagation is set along the z axis, and the polarization plane is restricted to the xy plane. The results indicate that the alignment of O 2 molecules in the z direction is weakly affected by varying the ellipticity when the total laser intensity is held constant. For rotation within the xy plane, the linearly polarized laser significantly excites rotational motion, with the degree of excitation increasing as the ellipticity increases. In contrast, under the influence of a circularly polarized laser, the angular distribution of O 2 molecules in the xy plane remains isotropic. Additionally, the effects of the initial rotational quantum number, the temperature of the O 2 molecules and the nuclear spin on laser-induced alignment are discussed.