Vibrational energy exchange rates in carbon monoxide

A pulsed supersonic CO laser has been sued to produce a time-dependent CO vibrational distribution which is strongly vibration-vibration pumped. The time evolution of the populations of individual vibrational states of the X ¹Σ⁺ and the A¹Π manifolds was observed through X state infrared emission and A-X ultraviolet emission. The X state first-overtone IR signals were observed from ν = 2 through ν = 40. The time-dependence of ν = 11, 17, 24, 29 and 35 was analyzed in detail. A-X (fourth positive) emission signals originating from ν = 1 to ν = 8 were observed and analyzed. In addition, the timing of the formation of C₂ was observed from the Δν = -1 sequence in the blue Swan-band emission. Kinetic modeling calculations have been performed which show good agreement with the measured experimental rise times. Near-resonance vibration-vibration transfer rates among CO(X ¹Σ⁺, ν) states to ν = 40 have been inferred at a gas temperature of 370 K. These calculations also reproduce the observed X state vibrational distribution and the low-ν relaxation data in the literature. An estimate of the internal X-A collisionally induced vibration-electronic coupling has also been obtained.