Studies of vibrational relaxation in OCS and CF4by pulsed photoacoustic techniques

摘要

We have used the pulsed photoacoustic technique to measure the effective collisional probabilities for relaxation of the lowest vibrational modes of OCS and CF4by several collision partners. The measured probabilities at 300 K are OCS by OCSmdash;(3.7plusmn;0.7)times;10minus;4; Hemdash;(8.0plusmn;0.3) times;10minus;4; Armdash;(0.96plusmn;0.3)times;10minus;4; H2mdash;(12.0plusmn;7.0)times;10minus;4; D2mdash;(12.9plusmn;2.5) times;10minus;4; N2mdash;(2.5plusmn;0.5)times;10minus;4; COmdash;(3.0plusmn;0.7)times;10minus;4; CF4by CF4mdash;(3.4 plusmn;0.2)times;10minus;4; Hemdash;(8.6plusmn;1.0)times;10minus;4; Armdash;(1.6plusmn;0.2)times;10minus;4. We also consider in some detail the acoustic waves generated by cylindrically symmetric laser excitation of a weakly absorbing gas in a cylindrical tube and how the signals produced by a microphone in the tube wall reflect the Vhyphen;R,T relaxation of the gas.