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Intra- and Intermolecular Inhomogeneities in the Course of Glassy Densification of Polyalcohols

To test basic assumptions inherent to most theories of molecular liquids and glasses, Infrared spectroscopy is carried out on short polyalcohols at temperatures ranging from far above to far below their glass transition. By analyzing specific vibrations, the thermal expansion of covalent bonds and hydrogen bridges is determined revealing striking differences. A comparison with density verifies the negligibility of \textit{intra}molecular expansion but exposes severe inhomogeneities on \textit{inter}molecular scale. This signals distinct roles in glassy densification and promotes an atomistic understanding.