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Athermal photofluidization of glasses
G J Fang1, J E Maclennan, Y Yi
1Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.
Nature Communications
|February 28, 2013
Summary
Azobenzene photo-isomerization causes athermal photofluidization by creating localized high temperatures. This phenomenon dramatically reduces the viscosity of organic glasses, enabling new applications in photonics and materials science.
Area of Science:
- Photonic Materials
- Organic Photophysics
- Glassy Systems
Background:
- Azobenzene derivatives are crucial organic photonic materials.
- Photo-induced trans-cis isomerization drives applications like data storage and nanorobotics.
- Athermal photofluidization, a key mystery, involves significant viscosity reduction with minimal temperature increase.
Purpose of the Study:
- To analyze relaxation dynamics in azobenzene-based glasses.
- To measure the transient local effective temperature during photo-isomerization.
- To elucidate the mechanism behind athermal photofluidization.
Main Methods:
- Analysis of relaxation dynamics in a dense monolayer glass of azobenzene-based molecules.
- Measurement of transient local effective temperature during photo-isomerization events.
Main Results:
- A high local effective temperature (T(loc)~800 K) was measured.
- This local temperature exceeds the glass transition temperature.
- Photofluidization occurs efficiently, with near 100% quantum efficiency.
Conclusions:
- Athermal photofluidization is driven by localized high temperatures generated by photo-isomerization.
- Each photon absorption creates a transient state exceeding the local glass transition temperature.
- This enables efficient overcoming of confining barriers, explaining the dramatic viscosity reduction.
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