This paper presents an experimental procedure to study state-to-state collisional dynamics by using tunable and pulsed laser techniques and timeresolved and dispersed fluorescence method. The decay processes of electronically and vibrationally excited iodine, B3Πou+(v＇=19), to the adjacent vibrational states in self-collisional events have been directly observed in experiments. The rate constants for the state-to-state vibrational transfer obtained are, kv(19→18) = (2.21±0.33)×10-11cm3s-1mol-1 and kv(19→20) = (1.44±0.20)×10-11cm3s-1mol-1. These results are in satisfactory agreement with the principle of detailed balance. In addition, the collision-free lifetimes and the radiationless quenching rate constants in B(v＇= 19) were also obtained in the experiments.