Isothermal transformation of supercooled liquid n-butanol near the glass transition: Polyamorphic transitions in molecular liquids investigated using Raman scattering

摘要

Raman investigations were carried out during an isothermal transformation of deeply supercooled liquid n-butanol, recently interpreted as a polyamorphic transition. Raman spectra indicate that the newly emerging state is a mixed crystal-liquid state, and not another amorphous state. The long-range order in crystallites was identified as reflecting that of the crystal. The time dependence of the O-H stretch spectrum indicates that the transformation is driven by the formation of a two-dimensional H-bonded network, according to the archetypal-layered structures of normal alcohols. The origin of the frustration of the crystallization in n-butanol can be explained from the consideration that the rearrangement of the hydrogen-bonded molecules is unavoidably prevented by the very low molecular mobility of the system only two degrees above T_g.