Energy transfer and isotopic enrichment in vibrationally pumped diatomic molecules

The preliminary results from two experiments on vibration-vibration pumped CO are reported. The first experiment is a demonstration of isotopic enrichment by vibration-vibration pumping. An ∼3000K translational temperature flowing mixture of CO, Ar and He is excited by a CO laser and the resulting non-equilibrium vibrational distribution is probed by laser induced fluorescence. In CO plus Ar mixtures, 13CO enrichments of a factor of three times the natural 13CO abundance are observed for high, v = 30, vibrational states. In CO plus Ar and He mixtures the 13CO enrichment is reduced to approximately its natural abundance. Calculations indicate that larger He mole fractions could result in relative enrichment of the 12CO isotope. The second experiment is a time and state resolved kinetics study of vibration-vibration pumped CO. A pulsed CO laser is used to produce a highly excited vibrational distribution. The vibrationally resolved overtone emission from the ground electronic state is monitored as a function of time for states v = 2 to 40. Electronic emission from the A-X band is also observed. In order to derive the kinetic rates for the various vibrational exchange processes, the data are compared with a kinetic model including all of the energy exchange terms. Preliminary calculations show reasonable agreement with the observed ground electronic state emission. 10 refs., 4 figs