HYDROGEN-BONDING IN GLASSY LIQUID WATER FROM RAMAN-SPECTROSCOPIC STUDIES

In order to investigate subtle differences in the local structure and bonding of amorphous ices, glassy Liquid water was produced by rapid c ooling of micrometer sized water droplets. Samples were first studied with power x-ray diffraction (PXRD) and differential scanning calorime try (DSC) to ensure that the production technique resulted in amorphou s material with low crystalline content. Solutions containing 5% D2O i n H2O and 5% H2O in D2O were vitrified, cooled to 12 K, and used to co llect Raman spectra of the decoupled O-D (Delta v(OD)=2440 cm(-1)) and O-H (Delta v(OH) =3302 cm(-1)) vibrations, respectively. Samples were then annealed from 90 to 180 K in temperature intervals of 10 K. Duri ng each annealing step the samples were held isothermally for 15 min b efore rapidly cooling them back down to 12 K for data collection. The transition from amorphous to crystalline material was observed to occu r between 150 and 160 K. Raman frequency shift data were then used to estimate the distribution in the hydrogen-bonded O-H--O distances usin g known correlations. The local bond strengths and O-H--O distances in vitrified liquid water were found to be very similar to those in vapo r-deposited amorphous water. (C) 1998 American Institute of Physics. [ S0021-9606(98)52243-X].