Multiple timescales in the photoswitching kinetics of crystalline thin films of azobenzene-trimers
| Autor: | Linus Pithan, F. Carlà, Sebastian Bommel, C Knie, Stefan Kowarik, C. Weber, R. Felici, David Bléger, Anton Zykov |
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| Rok vydání: | 2017 |
| Předmět: |
Diffraction
Materials science Kinetics 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences chemistry.chemical_compound Crystallography Azobenzene chemistry Chemical physics Mechanochemistry General Materials Science Thin film 0210 nano-technology Spectroscopy Layer (electronics) Optomechanics |
| Zdroj: | Journal of physics. Condensed matter : an Institute of Physics journal. 29(43) |
| ISSN: | 1361-648X |
| Popis: | Functional materials that exhibit photoinduced structural phase transitions are highly interesting for applications in optomechanics and mechanochemistry. It is, however, still not fully understood how photochemical reactions, which are often accompanied by molecular motion, proceed in confined and crystalline environments. Here we show that thin films of azobenzene trimers exhibit high structural order and determine the crystallographic unit cell. We demonstrate that thin film can be switched partially reversibly between a crystalline and an amorphous phase. The time constant of the photoinduced amorphisation as measured with real-time x-ray diffraction ([Formula: see text]220 s) lies between the two time constants (120 s and 2870 s) of the ensemble photoisomerisation processes that are measured via optical spectroscopy. Our observation of a photoinduced shrinking of the crystalline domains indicates a cascading process, in which photoisomerisation starts at the surface of the thin film and propagates deeper into the crystalline layer by introducing disorder and generating free volume. This finding is important for the rapidly evolving research field of photoresponsive thin films and smart crystalline materials in general. |
| Databáze: | OpenAIRE |
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