Absorption coefficients, frequency shifts and absorption cross sections measurements versus pressure at room temperature, for hydro-chlorofluorocarbon HCFC-141b using a tunable CW CO2 laser

Abstract

Infrared (IR) absorption in the spectral ranges of 10P (934.92-952.89 cm−1), 10R (969.15-982.13 cm−1), 9P (1037.43-055.62cm−1) and 9R (1071.88-084.62 cm−1) in Freon of HCFC-141b (CH3CCl2F) was studied by measuring the laser output power at each emitted spectral line versus pressure. A tunable continuous wave (CW) CO2 laser with an absorber cell located outside the laser cavity were used and the maximum output power of about 2.88 W on the line 10P(22) was achieved.The absorption coefficients of HCFC-141b for all emitted spectral lines were determined versus the gas pressure between 0.01-300 mbar, 0.01- 500 mbar, 0.01-450 mbar and 0.01-80 mbar for 10P, 10R, 9P and 9R branches respectively.The frequency shifts of the absorption lines of HCFC-141b in relative to the central frequencies of laser lines were calculated vs the pressure on the basis of the absorption coefficients.The chosen spectral ranges were selected according to IR spectrum of the studied gas given by HITRAN cross section database. So the absorption was achieved for HCFC-141b at the spectral lines of 10P, 10R, 9P and 9R branches emitted by a tunable CW CO2 laser.The absorption cross sections of HCFC-141b determined in this work were compared with the relevant data given by HITRAN cross section database and with the available measured results of reported work by others. The agreement was almost reasonable for all lines.