Molecular symmetry effects in the ionization ofCS2by intense few-cycle laser pulses

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Few-cycle pulses of 800 nm light cause ionization and dissociation of ${\text{CS}}_{2}$ 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-${\text{CS}}_{2}$ interactions in the strong-field regime, the wave packet of the rescattered electron destructively interferes with the antibonding $\ensuremath{\pi}$ orbital of $\text{CS}_{2}{}^{+}$ 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 ${\text{CS}}_{2}$ ionization spectra that we measure in the 700 attosecond domain using fast, highly charged ions corroborates that rescattering is not of importance when ${\text{CS}}_{2}$ 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.