DYNAMICAL STRUCTURE OF WATER BY RAMAN-SPECTROSCOPY

Raman spectra of liquid water have a broad background extended to 4000 cm(-1) as well as molecular vibrational modes. Depolarized Raman spec tra below 250 cm(-1) in liquid water are well interpreted with a super position of two damped harmonic oscillators and one Cole-Cole type rel axation mode. Two damped harmonic oscillators are interpreted as stret ching and bending vibration modes of a temporal tetrahedral-like struc ture of five water molecules. High-frequency Raman spectra between 160 0 cm(-1) and 4000 cm(-1) in liquid water are well explained by molecul ar vibration modes of a temporal C-2v tetrahedral-like structure aroun d oxygen atom. This interpretation of high frequency spectra is consis tent with the interpretation of low-frequency vibrational modes below 250 cm(-1). Moreover, the high frequency tail of the above Cole-Cole t ype relaxation mode could explain the broad background spectra in liqu id water. (C) 1998 Elsevier Science B.V.