Cooling Effects of CO2, CO2-N2 and CO2-He Gases by Absorption of Q-Switched Laser Radiations

Transient cooling of CO 2 and mixtures of CO 2 –N 2 , CO 2 –He was investigated in the pressure range of range of 5–460 Torr, using different wavelength radiations of the CO 2 laser, i.e. the P and R branches of 10.6 µm and 9.6 µm radiation. Temperature variations of the irradiated gases were detected by a condenser microphone through the pressure changes. Observed experimental results are explained, based on the variation of the vibrational relaxation times of the CO 2 molecule under different physical conditions.