| 日時: |
2009-08-26 14:00 - 15:00 |
| 場所: |
4号館2階輪講室1 |
| 会議名: |
Stuctural dynamics of photoinduced molecular switching in the solid state |
| 講演者: |
Professor Herve Cailleau (Institut de Physique de Rennes, Universite de Rennes) |
| 講演言語: |
英語 |
| URL: |
http://pfwww.kek.jp/pf-seminar/index.html |
| アブストラクト: |
A current challenge in science and technology is to direct the functionality of matter at the relevant smaller scale, not only ultra-small size but also ultra-short time. Thus a femto-second laser pulse may induce spectacular collective and/or cooperative phenomena in the solid state. This can trigger the transformation of the material towards another macroscopic state of different electronic and/or structural order, for instance from non-magnetic to magnetic or from insulator to conductor. Besides different itinerant electron systems materials with multi-functional molecules which can switch between two states are also promising. The switching of molecules in a material triggered by a femtosecond light pulse ensues the new established field of femto-chemistry in solution where photo-chemical processes are essentially independent. The physical picture of the dynamics of this switching in molecular materials will be discussed. The key point is that in the solid state different degrees of freedom of different nature play their part on different time scales and the pathway is complex, from the molecular to material length and time scales. The discussion will be based on recent investigation of the structural dynamics in multifunctional spin crossover compounds which are prototypes of molecular bi-stability in the solid state. The time-resolved x-ray diffraction and optical results show the dynamics span from sub-pico-second molecular photo-switching followed by volume expansion (nanosecond) and thermal switching
(microsecond). |
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