The β- and γ-band systems of ¹⁴NS and ¹⁵NS

Abstract

The spectra of ¹⁴NS and ¹⁵NS molecules are obtained in a 2450 mc./s. microwave oscillator discharge. Vibrational assignments of the β- and γ-systems are studied in more detail. Several hitherto unrecorded bands are satisfactorily explained as belonging to higher v', v" levels in the Deslandres schemes of both β- and γ-systems. The observed isotope shifts (¹⁴NS-¹⁵NS) provide confirmatory evidence for the proposed vibrational analysis. In the case of the γ-system, the v'=2 level of the upper state appears to be strongly perturbed showing a shift of about 38 cm.⁻¹ from the expected position. In the β-system, the isotopic shifts in the band-heads involving the v'=0 and 1 levels of the ²Δ_5/2 of the upper state show small deviations from expected values. The reality of these small deviations is established beyond doubt by the occurrence of the effect on the 0–0 sub-band which exhibits the isotopic head in a wavelength direction opposite to the expected one.