Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

Crystals

Tadahiko Ishikawa¹  Ken Onda² 

[1] Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo 152-8551, Japan;Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama 226-8502, Japan;

关键词: photo-induced phase transition;    charge order;    charge separation;    ultrafast spectroscopy;    vibrational spectroscopy;    metal-insulator transition;    strongly correlated electron systems;    electron-phonon interaction;    Pd(dmit)₂;    (EDO-TTF)₂PF₆;   

DOI  :  10.3390/cryst2031067

来源: mdpi

【 摘 要 】

Strongly electron-lattice- and electron-electron-correlated molecular crystals, such as charge transfer (CT) complexes, are often sensitive to external stimuli, e.g., photoexcitation, due to the cooperative or competitive correlation of various interactions present in the crystals. These crystals are thus productive targets for studying photoinduced phase transitions (PIPTs). Recent advancements in research on the PIPT of CT complexes, especially Et₂Me₂Sb[Pd(dmit)₂]₂ and (EDO-TTF)₂PF₆, are reviewed in this report. The former exhibits a photoinduced insulator-to-insulator phase transition with clearly assigned spectral change. We demonstrate how to find the dynamics of PIPT using this system. The latter exhibits a photoinduced hidden state as an initial PIPT process. Wide energy ranged time-resolved spectroscopy can probe many kinds of photo-absorption processes, i.e., intra-molecular and inter-molecular electron excitations and intramolecular and electron-molecular vibrations. The photoinduced spectral changes in these photo-absorption processes reveal various aspects of the dynamics of PIPT, including electronic structural changes, lattice structural changes, and molecular deformations. The complexities of the dynamics of the latter system were revealed by our measurements.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.