Dynamics of the CO2upper laser level as measured with a tunable diode laser

A tunable diode laser (TDL) operating in the 2140-2310 cm
^-1
wavenumber region is used to probe a conventional CW CO
2
laser discharge. Detailed vibrational populations in CO
2
are measured under lasing conditions, i.e., in the presence of an intense 10 μm field. The TDL is also used to investigate the rate of recovery of the populations in a variety of vibrational levels after the passage of an intense 10 μm pulse. This paper deals mainly with the behavior of the upper laser level, and the associated ν
3
mode. We show that electron deex-citation of the ν
3
mode is very important, and is responsible for the limitation of the ν
3
mode temperature observed previously. In typical gas mixtures, the ratio of the ν
3
mode electron deexcitation rate constant to the electron excitation rate constant is
\sim 3.5:1
.