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

A tunable diode laser (TDL) operating in the 2140-2310 cm-1wavenumber region is used to probe a conventional CW CO2laser discharge. Detailed vibrational populations in CO2are 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 ν3mode. We show that electron deex-citation of the ν3mode is very important, and is responsible for the limitation of the ν3mode temperature observed previously. In typical gas mixtures, the ratio of the ν3mode electron deexcitation rate constant to the electron excitation rate constant is~ 3.5:1.