The aim of this paper is to determine with accuracy the band strength of the strong u3 fundamental band of carbon disul hide CS2. By diode-laser spectroscopy, we have measured line by line the intensities for the I C32S2 form by the equivalent width method and by the line profile fitting method. To confirm our results, we have also measured 30 lines for the 13C32S2 isotopic species using a sample of CS2 in natural abundance. We have obtained for the band strength St = 1417cmp2 atm-I at 296K and this value is in good agreement with the values from the literature. P
IntroductionThe intensity of spectral lines provides important information for gas analysis and leads to essential results for molecules of atmospheric and astrophysical interest. In particular, the measurements of lines belonging to the more intense transitions are usually needed for these applications. However, for the very intense bands, accurate measurements of the band strength are more difficult to obtain. To record lines of these bands, the product PL of the gas pressure P and the absorption length L has to be small and thus it is difficult to achieve good relative precision.With a view to obtaining as good results as possible, we employed three different methods of absolute line intensity determination. First, we used the classical method of measuring the equivalent width of the line at low pressure (of the order of 0.1 mbar) and at very low path length to maintain the product PL at convenient values. The second method is based on the determination of the line strength by fitting a theoretical profile on the line broadened by an inactive gas such as nitrogen. In this case, the active gas pressure and the path length may become larger, and the line strength is extracted from nonlinear least squares fitting of the spectra with Voigt and Rautian profiles. Finally, as the isotopic substitution modifies the band strength value only slightly, a confirmation can be obtained by measuring the intensity of the lines for the same transition of the less abundant isotopic species.