A Tunable Difference Frequency Spectrometer for Quantitative Analysis of Heavy Molecules

A continuous-wave (cw) mid-infrared spectrometer based on laser difference frequency generation (DFG) in gallium selenide (GaSe) crystal was developed for quantitative analysis of heavy molecules. The spectrometer and its spectroscopic applications to study of molecular line parameters (such as line strength, pressure broadening coefficients) are presented. The first measurement, to our knowledge, of the self and air broadening coefficients for the ₇ 8 _2,7 8 _1,7 ethylene (C₂H₄) transition line at 958.1531 cm^–1 is reported.