Low temperature aging in a molecular glass:The case of: cis -methyl formate
| Autor: | Valeria Lauter, Artur Glavic, Andrew Cassidy, David J. Field, Mads R. V. Jørgensen, Oksana Plekan |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Methyl formate Diffusion General Physics and Astronomy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics 0104 chemical sciences Dipole chemistry.chemical_compound chemistry Electric field Deposition (phase transition) Neutron Formate Physical and Theoretical Chemistry 0210 nano-technology Glass transition |
| Zdroj: | Cassidy, A, Jørgensen, M R V, Glavic, A, Lauter, V, Plekan, O & Field, D 2021, ' Low temperature aging in a molecular glass : The case of: cis-methyl formate ', Physical Chemistry Chemical Physics, vol. 23, no. 29, pp. 15719-15726 . https://doi.org/10.1039/d1cp01332g |
| DOI: | 10.1039/d1cp01332g |
| Popis: | 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. This journal is |
| Databáze: | OpenAIRE |
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