Maximising rovibrational assignments in the ν1 band of NSCl by spectral analysis by subtraction of simulated intensities (SASSI)

The ν1 band of thiazyl chloride (NSCl) has been measured by high resolution FTIR spectroscopy, and studied using the spectral analysis by subtraction of simulated intensities (SASSI)-technique. This involves assignment and fitting of a component, creating a global simulation of the entire component to be subtracted from the experimental spectrum, and subsequent analysis of the resultant spectrum. Through this iterative procedure it has been possible to assign rovibrational transitions for seven components, with populations in the lower vibrational state as low as 2% of the total. The components are the 101 fundamental and 101311, 101322, and 101211 hotbands of 14N32S35Cl, the 101 fundamental and 101311 hotband of 14N32S37Cl, and the 101 fundamental of 14N34S35Cl. Rotational and centrifugal distortion constants beyond the quartic level have been obtained by fitting to Watson's A-reduced Hamiltonian in upper and lower states.