A two-color (3+ 1′) pump-probe scheme is employed to investigate Rydberg wave packet dynamics in carbon disulfide (C S2*). The state superpositions are created within the 4f and 5p Rydberg manifolds by three photons of the 400 nm pump pulse, and their temporal evolution is monitored with femtosecond time-resolved photoelectron spectroscopy using an 800 nm ionizing probe pulse. The coherent behavior of the non-stationary superpositions are observed through wavepacket revivals upon ionization to either the upper (12) or lower (32) spin-orbit components of C S2+. The results show clearly that the composition of the wavepacket can be efficiently controlled by the power density of the excitation pulse over a range from 500 GW cm2 to 10 TW cm2. The results are consistent with the anticipated ac-Stark shift for 400 nm light and demonstrate an effective method for population control in molecular systems. Moreover, it is shown that Rydberg wavepackets can be formed in C S2 with excitation power densities up to 10 TW cm2 without significant fragmentation. The exponential 1e population decay (T1) of specific excited Rydberg states are recovered by analysis of the coherent part of the signal. The dissociation lifetimes of these states are typically 1.5 ps. However, a region exhibiting a more rapid decay (≈800 fs) is observed for states residing in the energy range of 74 450-74 550 cm-1, suggestive of an enhanced surface crossing in this region.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry