Vibrational Relaxation of the Bending Mode of Shockhyphen;Heated CO2by Laserhyphen;Absorption Measurements

摘要

The vibrational relaxation characteristics of shockhyphen;heated CO2have been studied using a tuned CO2laser absorption technique. Absorptionhyphen;coefficient histories were obtained for a single rotational state in each of the 10deg;0 and 02deg;0 levels over the temperature range from 500 to 2000deg;K, and for 21 rotational states of the 10deg;0 level at 1000deg;K. These histories have been combined with translationalhyphen;rotational temperature histories based on interferometer measurements to calculate vibrational relaxation times for the bending mode. The results verify the mutual equilibrium of the bending and symmetrichyphen;stretch modes due to Fermi resonance. The bending mode relaxation times are approximately 10percnt; shorter than predicted from interferometer results using the ratio of specific heats. Furthermore, relaxation times based on measurements of different rotational states at 1000deg;K show a variation with quantum numberJ, indicating a possible rotational nonequilibrium during the vibration relaxation process.