Manifestations of collisions in the laser SRS – CARS diagnostics of hydrogen in rarefied gas mixtures

CARS diagnostics of hydrogen in rarefied gas mixtures is performed using the biharmonic laser pump based on the SRS by the vibrational hydrogen transition. The diagnostics is shown to be substantially affected by collisions, which result in variations in the linewidth and the frequency of the Raman-active transition. This influence is distinctly observed at pressures higher than 0.05 atm and depends on the composition of the buffer gas mixture.