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Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
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Low-temperature dynamics in amorphous polymers and low-molecular-weight glasses--what is the difference?
Ivan Yu Eremchev1, Yury G Vainer, Andrei V Naumov
1Molecular Spectroscopy Department, Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow reg., 142190, Russia.
Physical Chemistry Chemical Physics : PCCP
|December 25, 2010
Summary
Low-temperature dynamics in disordered solids are not universal. Single-molecule spectroscopy reveals that local dynamics depend on material structure and composition, challenging current glass dynamics concepts.
Area of Science:
- Materials Science
- Physical Chemistry
- Condensed Matter Physics
Background:
- Disordered solids exhibit universal low-temperature dynamics.
- Ensemble-averaging techniques obscure local dynamic process parameters.
Purpose of the Study:
- Investigate local dynamic processes in disordered solids using single-molecule (SM) spectroscopy.
- Examine the influence of internal structure and chemical composition on low-temperature dynamics.
Main Methods:
- Utilized single-molecule (SM) spectroscopy for direct observation of dynamic processes.
- Studied disordered solids with varying internal structures and chemical compositions.
Main Results:
- Observed dynamics in low-molecular-weight glasses and short-chain polymers deviate from established low-temperature glass dynamics concepts.
- Detected an additional dynamic contribution causing irreproducible spectral jumps and drifts on millisecond to minute timescales.
- In many small molecule and oligomer matrices, spectral dynamics were too rapid for spectra recording, resulting in irregular fluorescence flares.
Conclusions:
- Local dynamics of disordered solids at low temperatures are not universal.
- Dynamics are significantly influenced by the specific structure and chemical composition of the material.
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