Determination of broadening coefficients and intensities for overlapping spectral lines with application to the R (3,K) lines in the v₃ band of CH₃Cl

We have developed a method of extracting individual line parameters from overlapping absorption spectra recorded with a tunable diode-laser spectrometer. Assuming Voigt profiles for the individual lines, the overall absorption is expressed as the sum of the absorption coefficients of the recorded lines plus a small contribution due to neighboring lines. The computational procedure has been applied to the four R (3, K) lines, self-broadened and broadened by N,O, Ar and He, in the v band of CHCl at 736.3 cm. The intensities and collision-broadened widths are found to be linear functions of the broadener pressures, which implies negligible line-mixing effects between the K components. For all the perturbers considered the broadening coefficients of the R(3,K lines decrease significantly as K increases, in agreement with theoretical results.