DYNAMICS OF VIBRATIONAL WAVE-PACKETS IN THE C1-PI-U STATE OF CS-2

The dynamics of vibrational wave packets in the weakly predissociated C 1PI(u) of Cs2 have been examined by two color, femtosecond laser pump-probe techniques. The motion of the wave packet is detected by photoionizing the dimer with a time-delayed 620 nm pulse and monitoring the time- and energy-integrated photoelectron signal with a proportional counter. Since the anharmonicity of Cs2(C 1PI(u)) is slight (omega(e)/omega(e)x(e) almost-equal-to 700) and the ground state vibrational manifold is equilibrated at T almost-equal-to 550 K, wave packets consisting of the superposition of wavefunctions of more than 20 vibrational levels are formed that dephase in almost-equal-to 18 ps.