by intense ultrashort laser pulses*

We investigate the dissociative and non-dissociative ionization of a CS⁺ molecular-ion beam exposed to intense ultrafast laser pulses (780-nm, 25-fs, over the range 10¹² – 10¹⁵ W/cm² laser pulses at 10 kHz) by employing a coincidence three-dimensional momentum imaging technique. As expected, the C⁺ + S⁺ channel, which correlates with the lowest electronic states of CS²⁺, dominates over the entire intensity range studied. The measured kinetic energy release indicates that the ground and first excited states of CS²⁺ are the main contributors to this channel. A fraction (about 10%) of all CS²⁺ produced in these metastable states live long enough to reach the detector intact. We also observe the less likely (a few %) charge-asymmetric channel, C + S²⁺, while C²⁺ + S is not observed. The kinetic energy release in C + S²⁺ breakup is much smaller than that in the C⁺ + S⁺ fragmentation. Finally, both two-body breakup channels are found to be tightly aligned along the laser polarization.