Vibrational energy transfer in OH X 2Πi, v=2 and 1

Using an infrared pump/ultraviolet probe method in a flow discharge cell, vibrational energy transfer in OH X 2Πi has been studied. OH is prepared in v=2 by overtone excitation, and the time evolution of population in v=2 and 1 monitored by laser-induced fluorescence. Rate constants for vibrational relaxation by the colliders H2O, NH3, CO2, and CH4 were measured. Ratios of rate constants for removal from the two states, k2/k1, range from two to five.