Structural Features of Liquid DMSO from Temperature-Dependent Raman Spectroscopy and Theoretical Calculations
Dimethyl sulfoxide(DMSO)plays an im-portant role in chemistry,biology and in-dustry.The S=O stretching vibration serves as a sensitive probe of its struc-ture under different chemical environ-ments.However,spectral assignment for the S=O stretching vibration of liquid DMSO remains unclear due to the inter-ference of CH3 antisymmetric rocking and different aggregates,leading to the confusion in explaining the microstructures of liquid DMSO.Here,the S=O stretching spec-tra in pure DMSO and in extremely diluted CCl4 solution were investigated with temperature-dependent Raman spectroscopy.It is shown that CH3 antisymmetric rocking does not signifi-cantly interfere with the S=O band profile due to its low Raman intensity.Three decom-posed peaks at 1027,1042 and 1055 cm-1 in liquid DMSO show obviously different intensity variety upon the temperature increasing.Combined with quantum chemistry calculation on(DMSO)n(n=1-4)clusters,Raman spectra in the S=O stretching region were assigned and the simultaneous presence of the monomer,dimer and trimmer in liquid DMSO were conclud-ed.These results contribute to a more detailed molecular understanding of the structure of DMSO in the liquid state.
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