Orientation relaxation of a water molecule

Abstract

A new interpretation of the low frequency (up to 1 THz) dielectric spectra of water based on the angular velocity autocorrelation function. is proposed. We use Mori method to derive kinetic: equations for the angular velocity autocorrelation function and obtain the angular velocity correlation time from the comparison of the theoretical result with the inelastic: neutron scattering experiment. Using Hubbard relation we show that beside collective orientation relaxation, i.e. macroscopic dielectric relaxation, there is a single molecule orientation relaxation. It is much faster than the collective one and is displayed at the high frequency tail of the principal dielectric relaxation band. The analysis of the time dependence of the angular velocity autocorrelation function provides the evidence that the single-molecule relaxation is related to the molecules with partially broken H-bonds. © 2003 Elsevier Science B.V. All rights reserved.