Collisional relaxation of highly excited vibrational levels of the I2  X  1Σ+ g state using an I2 optically pumped laser

A new technique for the study of energy transfer processes using a cw optically pumped laser (OPL) is presented. Population removal rates from individual vibration–rotation levels of a nonfluorescing state may be measured. The rate measured is that out of the lower level of the lasing transition. A limiting case of a simple kinetic model, involving seemingly contradictory requirements of high OPL circulating power and low pump power, is described and experimentally realized. Rate coefficients are extracted by observing the change in spontaneous emission (side fluorescence) intensity from the OPL gain medium with and without OPL oscillation. Removal rates from several highly excited vibrational levels of I2 X 1Σ+g are measured using an Ar+ laser pumped I2 BO+u–X 1Σ+g(v′=43, v″=42, 64, and 76–83) laser.