Dynamic alignment of CO in an intense femtosecond laser field

Strong anisotropic angular distributions of the Cm+ (m = 1-3) and On+ (n = 1-2) ions have been observed when CO is irradiated by 110 fs, 810 nm laser pulses at the intensity of 1015 W/cm2, which are attributed to dynamic alignment or geometric alignment. We have studied the alignment mechanism using two linearly polarized laser pulses with crossed polarization. The first laser pulse strongly depletes the second laser pulse signal that produced in the lowest explosion pathway for all different delay times. The results clearly demonstrate that dynamic alignment dominates for CO under the experimental condition.