Vibrational–rotational spectra of 13CS and global multi-isotopologue analysis

Abstract

In total, 626 vibrational–rotational spectral lines of the Δv=1 transitions of 13C32S up to band v=5–4 have been measured with a Fourier-transform spectrometer at resolution 0.010cm−1. To calibrate accurately the spectral lines, a separate observation of the vibrational–rotational bands of 12C32S was made with simultaneous recording of the N2O spectrum in absorption, to serve as wavenumber standards, with dual sample cells at resolution 0.008cm−1. The spectral wavenumbers of 12C32S in turn become calibration standards. All present vibrational–rotational spectra of 13C32S and 12C32S, the reported vibrational–rotational spectra of 12C32S, 12C33S, 12C34S, and 13C32S, and the reported rotational spectra of 12C32S, 12C33S, 12C34S, 12C36S, 13C32S, 13C33S and 13C34S were subjected to a global multi-isotopologue analysis, which reduced them to molecular parameters in a single set. The wavenumbers of 3974 spectral lines, in total, comprising data of seven isotopologues were fitted with 22 isotopically invariant, traditional molecular parameters in a single set. As the normalized standard deviation is 1.38, the obtained fit is satisfactory. To facilitate the calculation of spectral wavenumbers, the values of the Dunham coefficients of 42 Yij for each of 12C32S, 12C33S, 12C34S, 12C36S, 13C32S, 13C33S, 13C34S, 13C36S, 14C32S, 14C33S, 14C34S and 14C36S, of which the spectra of the latter five isotopologues are not yet reported, were back-calculated with uncertainties using the evaluated 22 molecular parameters. The physical significance of the conventional treatments of the adiabatic and nonadiabatic corrections for Δ01C and Δ01S is discussed.