Molecular symmetry effects in the ionization of CS2 by intense few-cycle laser pulses

Few-cycle pulses of 800 nm light cause ionization and dissociation of CS2 in the intensity and temporal regime where, by contemporary wisdom, rescattering is expected to dominate laser-molecule interactions. However, our experiments indicate that in the case of laser-CS2 interactions in the strong-field regime, the wave packet of the rescattered electron destructively interferes with the antibonding pi orbital of CS2+ such that rescattering is essentially switched off. Consequently, dissociation becomes an almost nonexistent channel; long-lived singly, doubly, and triply charged molecular ions dominate the mass spectrum in the few-cycle regime, revealing the importance of molecular symmetry in strong-field ionization. Comparison with CS2 ionization spectra that we measure in the 700 attosecond domain using fast, highly charged ions corroborates that rescattering is not of importance when CS2 ionization is caused by intense laser light. Direct signature of enhanced ionization being switched off in the few-cycle domain is also obtained in our measurements.