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Photoinduced dissociation of donor–acceptor pairs in non‐magnetic phase of organic charge‐transfer crystal of tetrathiafulvalene–tetrabromo‐1,4‐benzoquinone
Author(s) -
Itoh Chihiro,
Nakata Yasuharu
Publication year - 2008
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200879838
Subject(s) - tetrathiafulvalene , chemistry , excitation , crystal structure , crystal (programming language) , dissociation (chemistry) , benzoquinone , crystallography , acceptor , photochemistry , molecule , condensed matter physics , programming language , biochemistry , physics , organic chemistry , computer science , electrical engineering , engineering
Abstract We have studied 532 nm laser‐induced changes in the infrared reflection of a charge‐transfer (CT) crystal of tetrathiafulvalene (TTF) and tetrabromo‐1,4‐benzoquinone (BA) at 4 K. The spectra of the fractional change (Δ R / R ) were characterized by dips situated in proximity to the structures ascribed to the a g ‐mode vibrations of TTF + and BA – at low excitation intensity. However, the excitation above 0.2 W cm –2 gave structures characterized by the inverted shape of the a g ‐mode structures, indicating that the laser excitation reduced the intensity of the a g ‐mode structures. The appearance of the a g ‐mode structures is associated with loss of the inversion centre of the crystal due to the dimerization of TTF + and BA – ; hence, the intensity reduction of the a g ‐mode structures is ascribed to dissociation of TTF + ‐BA – pairs. We found that Δ R / R increased super‐linearly with enhancing excitation intensity. The result suggests that the dissociation involves a multi‐quantum process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)