The Experimental Determination of the Intensities of Infrared Absorption Bands. IV. Measurements of the Stretching Vibrations of OCS and CS2

Abstract

The absolute intensity of the infrared stretching vibrations of the molecules CS₂ and OCS have been measured. For CS₂, the intensity of ν₃ was found to be 7560×10¹⁰ cycles sec⁻¹ (cm of vapor at NTP)⁻¹. For OCS, the results were 110 and 7900×10¹⁰ for ν₁ and ν₃. A normal coordinate analysis of the stretching vibrations of OCS was carried out to obtain ∂μ/∂r for the bonds and to compare them with those for CS₂ and the previously obtained results for CO₂. The results for a reasonable value of the interaction constant were 6.7 and 4.3×10⁻¹⁰ esu for the CO and CS bonds, while in CO₂ and CS₂ they were 6.0 and 5.6×10⁻¹⁰ esu. The bearing of these results on the amount of resonance in OCS is discussed. Arguments are presented which suggest that, in spite of the electronegativity difference between oxygen and sulfur, resonance in OCS is not markedly different from that in CO₂ and CS₂.