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Study of glassy and crystal ethanol by broadband nuclear magnetic resonance

Deuterated ethanol (C2D5OD) was studied by means of broadband nuclear magnetic resonance at fields up to 12 T. Ethanol is used as an ideal model system for properties of glassy states. By varying temperature (30 K - 160K) and thermal history of the sample two stable solid states were achieved - crystalline ethanol and ethanol glass. Difference between these two states was verified by T1 relaxation measurements, which are at least an order of magnitude longer in crystal than in glass. Relaxation time measurements are in agreement with known results from the literature [1]. In addition, here presented experimental data was measured in broader temperature range and, for the first time, at higher frequencies. Spectrometric measurements do not show any distinction between crystaline and glassy state, however, they do provide insight into the dynamics of methyl groups. Rotations of methyl groups are showed to be suppressed below 120 K and activated above 125 K. Activation of rotational degrees of freedom at relatively high temperatures implies methyl group confinement within ethanol crystal structure in both solid states investigated. [1] T. Eguchi, G. Soda, and H. Chihara, Molecular Physics 40, 681 (1980).

D-ethanol ; glass ; nuclear magnetic resonance

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