Field-Free Molecular Orientation Generated from CyclicRotational States by Using Two Trains of Half-Cycle Pulses

Abstract

We show that two trains of half-cycle pulses (HCPs) with differentamplitudes irradiating alternately on polar molecules can achieve aremarkable enhancement of field-free orientation compared with the caseof an equal amplitude HCPs train for the same pulse separation. Thiskind of orientation enhancements is mainly due to an optimal adjustmentof the population distribution on every field-free angular momentumeigenstate, in which the populations on the undesired states of highangular momenta are effectively suppressed, and the populations on thedesired states of low angular momenta are correspondingly promoted.