The solvation of SOH group in hydrated HSO₄⁻(H₂O)_n clusters

Abstract

The S=O stretching and SOH bending peaks in the vibrational spectra of HSO4−(H2O) n, with n up to 6, are analyzed by both harmonic analysis and ab initio molecular dynamics simulation. The SOH bending mode is found to be much more sensitive to the extent of hydration and to the fluctuation of hydrogen bonds than the S=O stretching mode. The SOH donor hydrogen bond is gradually stabilized by n = 4, and further shortened up to n = 6, which is the key factor to understand the trend of evolution observed in the infrared multiple photon dissociation spectra.