Diode-laser measurements of H2-broadening coefficients in the ν5 band of C2H2

H2-broadening coefficients have been measured for 29 lines of acetylene in the P and R branches of the ν5 band. These lines, located in the spectral range 640–810 cm−1, were recorded using a tunable diode-laser spectrometer. We obtain broadening coefficients that are significantly larger than previous experimental data. A comparison is also made with results calculated from a semiclassical theoretical model. The validity of this model for a light perturber such as H2 is questioned.