EXCIMER FORMATION KINETICS IN LIQUID-CRYSTALLINE ALKYLCYANOBIPHENYLS

被引:78
作者
IKEDA, T
KURIHARA, S
TAZUKE, S
机构
[1] Photochemical Process Division, Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Midori-ku, Yokohama 227
关键词
D O I
10.1021/j100380a008
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Excimer formation kinetics of three 4-cyano-4′-alkylbiphenyls (nCB) (alkyl = pentyl (5CB), hexyl (6CB), and octyl (8CB)) were studied by steady-state and time-resolved fluorescence spectroscopy. Excimer formation was significantly enhanced in nematic (N) state compared with isotropic (I) state but depressed in the smectic A (SA) state, although orientational ordering of mesogens in the SA state is much higher than in the N state. Time-resolved fluorescence spectra demonstrated the existence of the ground-state association of mesogens in the N phase, which produced excimer directly on excitation. Kinetical analysis of the excimer formation on the basis of a model that included the ground-state association of the mesogenic chromophores revealed that the rate constants of excimer formation and dissociation in nCB showed discrete change at temperatures close to the N-I phase transition temperatures. © 1990 American Chemical Society.
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页码:6550 / 6555
页数:6
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