Abstract
At ambient pressure, glycerol undergoes a liquid-glass transition at Tg =187 K, and the glass state was well
studied. While, at room temperature glycerol undergoes a pressure induced liquid-glass transition at about
Pg= 5 GPa. The liquid-glass transition of glycerol was studied under high pressure using Raman scattering
spectroscopy. According to the pressure dependence of O-H stretching mode frequency, the intermolecular
hydrogen bond distance decreased gradually in a liquid state, and it becomes nearly constant in a glassy state
indicating the suppression of the free volume in a glass state. The difference between the ambient pressure
frozen glass state and the high pressure frozen glass state was discussed. It is found that the characteristic
length of medium range order is close to the size of a cyclic trimer of glycerol molecules predicted
theoretically by Uchino and Yoko. The pressure induced structural change of glycerol can be essentially the
shrinkage of voids and cyclic trimers remain at least up to 11 GPa.
