Investigation of nonequilibrium rf-discharge plasma in nitrogen using the method of wide-band CARS spectroscopy

The method of wide-band spectroscopy of coherent anti-Stokes Raman scattering of light (CARS) is used for the first time to investigate low-temperature inductive-capacitive radio-frequency discharge (rf-discharge) plasma in nitrogen at a pressure of 20 torr and specific power up to $3$ W/cm$^3$. A disturbance of thermodynamic equilibrium over internal degrees of freedom of nitrogen is observed in gas-discharge plasma. The function of distribution of molecules over vibrational levels $\nu=0-4$ is described by the Treanor distribution, and that over rotational levels – by the Boltzmann distribution. Computer codes are developed for analyzing CARS spectra under conditions of disturbance of thermodynamic equilibrium over internal degrees of freedom of nitrogen molecules.