Absorption coefficients, frequency shifts and absorption cross sections measurement versus pressure at room temperature, for hydrofluorocarbon HFC-134a, using a tunable CW CO2 laser

Abstract

Infrared absorption in the spectral ranges of 934.92–952.89 cm−1, 969.15–982.13 cm−1, 1037.43–1055.62 cm−1 and 1071.88–1084.62 cm−1 versus pressure of hydro fluorocarbon CH2FCF3 was studied using a tunable CW CO2 laser emission on lines from 10P, 10R, 9P and 9R branches with a maximum output power of 3.44 W (at 10P (24)). The laser was provided with an absorber cell which is located outside the laser cavity.The absorption coefficients of HFC-134a molecule were determined versus the gas pressure between (0.2–800 mbar), (0.2–45 mbar), (0.2–450 mbar) and (0.2–80 mbar) for lines from 10P, 10R, 9P and 9R branches respectively. The frequency shifts of the absorption lines of HFC-134a in relative to the central frequencies of laser lines were calculated vs. the pressure on the basis of these absorption coefficients. The chosen lines were taken according to IR spectrum of the investigated gas given by HITRAN cross section database. So the absorption was achieved for HFC-134a at the spectral lines of 10P-9R branches situated from 10P (10) to 9R (30) emitted by a tunable CW CO2 laser.The absorption cross sections of HFC-134a determined in this work were compared with the relevant data given by HITRAN cross section database and a good agreement was observed almost for all lines.