Pressure-induced self-broadening and frequency shift measurements of absorption lines of acetylene using tunable diode laser absorption spectroscopy

Diode laser spectroscopy is used to investigate pressure-induced self-broadening as well as frequency shifts of several absorption lines in the nu (1) + 3 nu (3) overtone band around 780 nm region. A 35 meter path-length multipass cell is used to measure absorption directly as well as with the wavelength-modulation technique involving detection at first and second harmonics of the modulation frequency. Acetylene pressures in the 5-600 Torr range are used. Absorption linewidths are measured with Fabry-Perot interferometer having a free spectral range of 750 MHz. Frequency shift measurements and pressure-broadening coefficients of some spectral lines are reported for the first time. (C) 2001 Elsevier Science Ltd. All rights reserved.