Low temperature aging in a molecular glass: the case of cis-methyl formate

文献情報

出版日 2021-07-19

DOI 10.1039/D1CP01332G

インパクトファクター 3.676

著者

Andrew Cassidy, Artur Glavic, Valeria Lauter, Oksana Plekan, David Field

原文を見る

要旨

Glassy films of cis-methyl formate show spontaneous dipole orientation on deposition from the vacuum, the so-called ‘spontelectric effect’, creating surface potentials and electric fields within the films. We follow the decay of these fields, and their accompanying dipole orientation, on the hours timescale at deposition temperatures between 40 K and 55 K. Our data trace the low temperature ‘secondary decay’ mechanism, at tens of degrees below the glass transition temperature of 90 K. We show that secondary decay is due to molecular rotation, with associated activation energies lying between 0.1 and 0.2 eV. Diffusion is absent, as established from published neutron reflectivity data. Using an analytical model for the spontelectric effect, data are placed on a quantitative footing, showing that angular motion in excess of 50° reproduces the observed values of activation energies. Exploitation of the spontelectric effect is new in the study of glass aging and is shown here to give insight into the elusive processes which take place far from the molecular glass transition temperature.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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