Multispectrum fitting measurements of line parameters for 5-μm cold bands of acetylene

Using FT spectra (unapodized FWHM: 0.002 cm(-1)) of acetylene (C2H2)-C-12, absolute line positions have been measured (average accuracy: +/-0.0002 cm(-1)) between 1860 and 2180 cm(-1) in the 3nu(5)(1), (2nu(4)+nu(5))I-1, and (2nu(4)+nu(5))(II)-I-1 cold bands, improving the wavenumbers previously published by Pliva under a resolution of about 0.03 cm(-1). Absolute intensities have been obtained for more than 130 lines, with a mean accuracy of +/-5%, the accuracy of the amount of (C2H2)-C-12 in the sample being estimated to be better than 2%. For each band, the vibrational transition dipole moment squared has been determined, as well as empirical Herman-Wallis coefficients. Self-broadening coefficients have been measured at room temperature for more than 120 lines. No striking vibrational dependence has been observed for the self-broadening coefficients, and a polynomial expansion describing the rotational dependence is given. Furthermore, self-shifting coefficients have been measured for 89 lines, together with more than 150 absolute line positions. A multispectrum fitting procedure has been used to retrieve the line parameters from the spectra, and cross comparisons have been performed on a few lines between two different codings of this procedure. (C) 2002 Elsevier Science Ltd. All rights reserved.