Diode laser spectroscopic measurement of line shape of (nu(1)+3 nu(3)) band transitions of acetylene

A near-infrared diode laser spectrometer is set up to study the absorption line shape of acetylene in the 782 nm region. The second-derivative spectra recorded by source modulation technique have enhanced sensitivity. Careful choice of operating current and diode temperature leads to distortion-free line shape for six rotational components of the (v(1) + 3v(3)) overtone-co mbination mode of acetylene. Self- and nitrogen-broadening coefficients and line-strength parameters have been extracted by fitting the observed line shape with Voigt profiles. There is no evidence of the effect of velocity c hanging collisions on the line shape in this near-infrared band.