Intracavity absorption of CO2 laser radiation by chlorofluorocarbon (CFC) gases

Intracavity absorption method was applied to determine the absorption coefficients of trichlorofluorocarbon CCl₃F (CFC-11), dichlorodifluorocarbon CF₂Cl₂ (CFC-12) and chlorodifluorocarbon CHClF₂ (CFC-22) vs. the pressure in the cell inside the cavity of a tunable CO₂ laser at different spectral lines on branches 9R and 10P.The laser output power was measured vs. the gas pressure at different spectral lines on branches 9R, 9P, 10R and 10P of CO₂ molecule transitions. A strong absorption was observed for lines of 9R and 10P branches, whereas a weak absorption was noticed for lines of 9P and 10R branches.The calculation of absorption coefficients was restricted for 9R and 10P due to the oscillating variation of the output power of CO₂ laser vs. the CFC pressure, which was occurred for the lines of 9P and 10R.On the basis of absorption coefficients, the absorption cross-sections for CFC-12 were calculated and compared with the absorption cross-sections found from the previous experiment (where the cell was located outside the cavity), NIST and HITRAN databases, respectively.The obtained data could be useful for CFC gases detection as pollutants in the atmosphere.