Charge and Structural Dynamics in Photoinduced Phase Transition of (EDO-TTF)2PF6 Examined by Picosecond Time-Resolved Vibrational Spectroscopy

• Published in: Journal of physical chemistry. C 2012-03, Vol.116 (9), p.5892-5899
• Main Authors: Fukazawa, Naoto, Shimizu, Minoru, Ishikawa, Tadahiko, Okimoto, Yoichi, Koshihara, Shin-ya, Hiramatsu, Takaaki, Nakano, Yoshiaki, Yamochi, Hideki, Saito, Gunzi, Onda, Ken
• Format: Article
• Language: eng ; jpn
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Infrared and raman spectra and scattering; Metal-insulator transitions and other electronic transitions; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp210708q

Using time-resolved near-infrared reflectance spectroscopy and time-resolved mid-infrared vibrational spectroscopy, we studied photoinduced phase transition of the charge-ordered insulating phase in a charge-transfer complex (EDO-TTF)2PF6 (EDO-TTF: ethylenedioxy-tetrathiafulvalene) in the hundred picosecond range after photoexcitation. The temporal profiles at 0.83–1.03 eV, which are a characteristic of the photoinduced charge-disproportionate phase immediately after photoexcitation, suggested the formation of a new metastable phase in the hundred picosecond range. Time-resolved vibrational spectra at 1300–1700 cm–1, where charge- and structure-sensitive CC stretching vibrational modes are located, elucidated that the nature of the new phase is very close to that of the high-temperature metallic phase and it takes about 100 ps for the new phase to emerge accompanied with charge and structure fluctuation.