Low frequency Raman scattering from aqueous sucrose solution

Low frequency Raman spectra of aqueous sucrose solution with percent sucrose concentration c=85 have been recorded as a function of temperature in the range 200–353 K. The line shape of the spectrum has been analysed using a model by Gochiyaev, Malinovski, Novikov and Sokolov (GMNS). Boson peak frequency ωm is found to decrease with increasing temperature from ∼46 cm−1 at 200 K to ∼28 cm−1 at 353 K. Spectral intensity and relaxation time change discontinuously at T1=313 K. No discontinuity is observed near the bulk transition temperature Tg=265 K measured by differential scanning calorimetry (DSC). Renormalised boson peak frequency ω0 approaches zero at T2 ∼363 K which, according to the GMNS model, is the temperature at which vibrational modes soften. There appears to be another inelastic peak around 12 cm−1. Presence of two inelastic peaks has not been observed before.