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

Abstract

The ν 1 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 1 0 1 fundamental and 1 0 1 3 1 1 , 1 0 1 3 2 2 , and 1 0 1 2 1 1 hotbands of 14N 32S 35Cl, the 1 0 1 fundamental and 1 0 1 3 1 1 hotband of 14N 32S 37Cl, and the 1 0 1 fundamental of 14N 34S 35Cl. 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.