Investigation of the distribution of CO$_2$ molecules between vibrational–rotational levels in a glow discharge by the method of pulsed diode laser spectroscopy

A laser spectrometer for the investigation of a nonequilibrium molecular plasma was constructed. Diode lasers with a record width of a continuous frequency tuning range ($\gtrsim$10 см$^{-1}$) were used in this spectrometer. The spectrometer response time ($\lesssim$10 nsec) made it possible to use liquid nitrogen to cool the diode lasers so that the resolution was at least $\sim$10$^{-3}$cm$^{-1}$ when the tuning rate was $\sim$10$^5$cm$^{-1}$/sec. An investigation was made of the distribution of the vibrational and rotational energies between the internal degrees of freedom of the CO$_2$ molecules and the gas temperature in a glow discharge was determined.