Pressure Dependence of Resonance Fluorescence Lifetimes in SF(6) and SF(6)-Air Mixtures.
A pilot study is described in which the resonance of the 10.6-microm CO(2) laser radiation with the nu(3) vibrational level of the SF(6) molecule is used to explore the effect of gas density on the time response of fluorescence. A slow increase of the fluorescent decay time with pressure of pure SF(6) is found that is interpreted in terms of a degree of equilibrium between vibrational and translational temperatures. In SF(6)-air mixtures, however, the increase of air pressure from 0 atm to 1 atm produces a proportional increase of the time constant from milliseconds to seconds in a process in which the vibrational-translational relaxation time is very small compared with the bulk cooling time determined by the thermal diffusivity. The results are compared with previous studies using Q-switched pulse excitation.
Garbuny
M
M
Feichtner
J D
JD