Controlling LiH molecular orientation via rovibrational pre-excitation by utilizing infrared laser pulses and terahertz half-cycle laser pulses

Abstract We theoretically investigate the effect of rovibrational pre-excitation on molecular orientation. Infrared laser pulses are employed to manipulate the molecular vibrational wave packet and control the rovibrational transitions of LiH molecules. Two rovibrational pre-excitation schemes are proposed to examine the influence of the vibrational quantum number v and rotational quantum number J on the molecular orientation degree. Our results demonstrate that molecular orientation is enhanced when J is constant and v increases. When both v and J change concurrently, it is found that changes in J have a more significant effect on molecular orientation than changes in v . Additionally, we discuss the impact of the electric field amplitude and carrier-envelope phase in both pre-excitation schemes.