Optothermal spectroscopy of ethylene using a tunable waveguide CO2 laser

The results are given of a study of optothermal linear and nonlinear absorption spectra of ethylene. An investigation was made of the dependence of the optothermal signal on the pressure of the absorbing gas and on the modulation frequency. Measurements were made of the collisional selfbroadening coefficient of ethylene: 13.2 ± 0.7 MHz/Torr.