Raman spectroscopic study of glassy water in dilute lithium chloride aqueous solution vitrified under pressure

We vitrify dilute lithium chloride (LiCl) aqueous solutions (2.0-10.0 mol % solute) at about 0.5 GPa using a needle-type pressure device developed for cooling a liquid material rapidly, and measure Raman spectra of the vitrified solution at 1 atm and 25 K. The OH stretching vibrational modes of the vitrified solution seem to consist of a OH stretching vibrational mode of high density amorphous ice (HDA) of pure water and that of glass of highly concentrated LiCl aqueous solution. The Raman profile resembles more and more that of HDA as the solute concentration decreases. When the temperature of the vitrified solution increases at 1 atm, the Raman profile suddenly changes to that of low density amorphous ice around 135 K and the transformed profile goes to that of I(c) around 160 K. This transformation behavior seems to correspond to a transformation behavior of HDA. These results suggest that the portion of solvent water in the dilute LiCl aqueous solution vitrified under pressure may form HDA-type molecular arrangements. (C) 2002 American Institute of Physics.