Generalized relaxation equations for vibrational and rotational molecular kinetics in gas flows

Sukhinin, G. I.

doi:10.1007/bf00909687

Cited by 3 publications

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References 3 publications

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“…This can be done by suitably weighting the state-resolved rate constants at a given temperature. We have employed the following approximate expression, 67,90 which has been often used to this aim: 20,33,67,79 where E i and E j are the energies of the i and j rotational levels, 〈V〉 is the average collision velocity at temperature T, k ij is the rate coefficient for the i f j transition at the same temperature, and 〈E n 〉 ) ∑ i N i *E i n are the moments of the rotational energy distribution with N i *, the equilibrium population of the i level, given by where g i is the nuclear statistical weight of the state (1 in all cases for CO) and Q is the partition function.…”

Section: Resultsmentioning

confidence: 99%

Low-Temperature Rotational Relaxation of CO in Self-Collisions and in Collisions with Ne and He

et al. 2005

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The low-temperature rotational relaxation of CO in self-collisions and in collisions with the rare-gas atoms Ne and He has been investigated in supersonic expansions with a combination of resonance-enhanced multiphoton ionization (REMPI) spectroscopy and time-of-flight techniques. For the REMPI detection of CO, a novel 2 + 1' scheme has been employed through the A(1)Pi state of CO. From the measured data, average cross sections for rotational relaxation have been derived as a function of temperature in the range 5-100 K. For CO-Ne and CO-He, the relaxation cross sections grow, respectively, from values of approximately 20 and 7 A(2) at 100 K to values of approximately 65-70 and approximately 20 A(2) in the 5-20 K temperature range. The cross section for the relaxation of CO-CO grows from a value close to 40 A(2) at 100 K to a maximum of 60 A(2) at 20 K and then decreases again to 40 A(2) at 5 K. These results are qualitatively similar to those obtained previously with the same technique for N(2)-N(2), N(2)-Ne, and N(2)-He collisions, although in the low-temperature range (T < 20 K) the CO relaxation cross sections are significantly larger than those for N(2). Some discrepancies have been found between the present relaxation cross sections for CO-CO and CO-He and the values derived from electron-induced fluorescence experiments.

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