DMSO-Water Clustering in Solution Observed in Soft X-ray Spectra

The significant deviation from the ideality of dimethyl sulfoxide (DMSO)/water mixtures can be addressed based on the change of the local molecular orbitals of each solvent upon mixing. Oxygen K-edge absorption and emission spectra of DMSO/water solutions were measured using the liquid microjet technique. The spectra demonstrate that the hydrogen bond network in liquid water is already influenced at small DMSO concentrations, and at the molar fraction x(DMSO) = 0.43 we find strong evidence of DMSO-water clustering reflected by the influence on the occupied molecular orbitals.