Time-resolved studies of state-to-state vibrational energy transfer: I2(B3IIou+:v′ = 19) + He

This paper presents an experimental procedure to study state-to-state collisional dynamics by using tunable and pulsed laser techniques and time-resolved and dispersed fluorescence methods. For the first time, the decay processes of electronically excited iodine, B³II_ou⁺ (v′ = 19), to the adjacent vibrational states in collisions with He molecules have been directly observed in real time. The rate constants for the state-to-state vibrational energy transfer obtained are, k,_vHe(19→18) = (2.76±0.05)x10^?11cm³s^?1 molecule^?1 and k_vHe(19→20) = (1.65±0.04) × 10^?11 cm³s^?1 molecule^?1. These results are in satisfactory agreement with the detailed balance principle.