Temperature dependence of the Raman spectra of amorphous glucose in the glassy and supercooled liquid states

The Raman spectra of amorphous glucose between 300 and 4000 cm(-1) over the temperature range 15-55 degreesC are reported. The spectra were recorded a t several temperatures both below and above the glass transition temperatur e, T-g. A two-dimensional covariance spectrum was computed and a least-squa res analysis was used to quantify the temperature dependences observed in t he spectra, Several vibrational bands were found to be sensitive to the tem perature of the material. Some bands also show a changing temperature depen dence around the glass transition. A Fermi-type function was found to be su itable as an empirical phenomenological model for the observed changes in t he spectra, The wavenumber shifts and intensity changes observed in the spe ctrum were related to the intramolecular vibrations by a normal coordinate analysis of a single glucose molecule. The spectral changes in the nu (O-H) stretching region suggest a weakening of the hydrogen bond network at the glass transition. Other observed spectral changes suggest a weakening of th e van der Waals interactions with increasing temperature, but these changes seem not to be related to the glass transition, Copyright (C) 2000 John Wi ley & Sons, Ltd.