Femtosecond-laser-induced alignment in Coulomb explosion of N2

The dynamic process of laser-induced alignment in Coulomb explosion of N 2 has been studied using linearly and circularly polarized, 800 nm, 40 fs Ti:sapphire laser pulses at intensities of 10 14 to 10 16 W cm −2 . The fragment ions produced were observed for the different polarizations with an equal E -field along the detection axis. The intensity-dependent ratio of fragment ion signals has shown that the 40 fs pulses can never align the molecules during the ultrafast interaction at an intensity less than ∼10 15 W cm −2 , and the dissociative molecular ions start to be aligned at higher intensity. The degree of alignment is increased with an increase in the charge of the dissociative molecular ions.