Journal of Chemical Physics, Vol.104, No.18, 6938-6948, 1996
Lifetime Measurements of Selectively Excited Rovibrational Levels of the V B-1(2) State of Cs2
The radiative lifetimes of selectively excited rovibrational levels of the V B-1(2) state of the CS2 molecule have been measured under collision-free conditions in a cold molecular beam using a pulse-modulated frequency-doubled single-mode cw dye laser. Pure exponential fluorescence decays ware found for all excited levels. The lifetimes, scattering considerably in the range of 2-13 mu s, give evidence of interactions of the V B-1(2) state with background states. A deperturbation analysis performed for rotational levels involved in local two-level interactions yields detailed quantitative information on the V B-1(2) state and on the background levels. It is shown that these levels represent rovibrational levels of the B-2((3)A(2)) state and highly excited rovibrational levels of the X (1) Sigma(g)(+) electronic ground state. The coupling mechanisms are : (1) the spin-orbit interaction between the V B-1(2) state and the B-2((3)A(2)) state where the latter is coupled to the X 1 Sigma+g ground state by spin-orbit/vibronic and spin-orbit/Coriolis interaction and (2) the Coriolis coupling of the V B-1(2) state to the X (1) Sigma(g)(+) ground state. Further sources of perturbations are the spin-uncoupling in the (3)A(2) state and the Renner-Teller coupling of the V B-1(2) state to the (1)A(2) state. From the measured radiative lifetimes of the background states information on the electronic structure of the CS2 molecule is gained.
Keywords:QUANTUM BEAT SPECTROSCOPY;CARBON-DISULFIDE;LASER;FLUORESCENCE;ZEEMAN;RESOLUTION;EMISSION;DECAY;SO2