Differential Raman cross section of dimethyl sulfide

Abstract

Biogenic sulfur compounds such as dimethyl sulfide (DMS) are important contributors to the global carbon cycle. The differential Raman cross section of DMS relative to the nitrogen fundamental, σ_DMS, has been measured at several excitation wavelengths in order to assess the applicability of Raman spectroscopy for the direct quantitative measurement of this compound. At 488 nm, σ_DMS for the ν₆ carbon–sulfur stretching mode was found to be 4.9 ± 1.6, while for the ν₂ carbon–hydrogen stretching mode it was 2.8 ± 0.9. Using, KrF laser excitation, values for σ_DMS could be measured simultaneously at two excitation wavelengths, 248.32 and 248.69 nm. The average values of σ_DMS for 248-nm excitation based on measurements at these two excitation wavelengths were 3.5 ± 1.4 for the carbon–sulfur stretching mode and 4.6 ± 0.6 for the carbon–hydrogen stretching mode. The results indicate that no significant resonance enhancement of σ_DMS for either mode occurs, although they show some slight enhancement of the cross section for the ν₂ band (CH stretching mode). It was concluded that the measured values of σ_DMS are high enough to allow the quantitative detection of DMS at the millimolar level. Copyright © 2010 John Wiley & Sons, Ltd.