MODE-SPECIFIC VIBRATIONAL REORGANIZATION ENERGIES ACCOMPANYING PHOTOINDUCED ELECTRON-TRANSFER IN THE HEXAMETHYLBENZENE TETRACYANOETHYLENE CHARGE-TRANSFER COMPLEX

被引:201
作者
MARKEL, F
FERRIS, NS
GOULD, IR
MYERS, AB
机构
[1] UNIV ROCHESTER, DEPT CHEM, ROCHESTER, NY 14627 USA
[2] UNIV ROCHESTER, CTR PHOTOINDUCED CHARGE TRANSFER, ROCHESTER, NY 14627 USA
[3] EASTMAN KODAK CO, DIV ANALYT TECHNOL, ROCHESTER, NY 14650 USA
[4] EASTMAN KODAK CO, CORP RES LABS, ROCHESTER, NY 14650 USA
关键词
D O I
10.1021/ja00041a045
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Resonance Raman excitation profiles have been measured across the broad, intense charge-transfer absorption band of the hexamethylbenzene/tetracyanoethylene complex in CCl4 solution. Nonresonant Raman spectra of the complex and its perdeuterated derivative in the solid state have also been obtained with excitation at 1064 nm. Absorption of light within the charge-transfer band results in electron transfer from hexamethylbenzene to tetracyanoethylene to form a radical-ion pair. The geometry change along each vibrational mode as a result of this photoinduced electron transfer and the accompanying internal reorganization energies have been determined through quantitative simulation of the absorption spectrum and absolute resonance Raman intensities using time-dependent wavepacket propagation methods. The largest individual contributions to the total measured reorganization energy of approximately 3500 cm-1 arise from the presumed donor-acceptor intermolecular stretching mode at 165 cm-1 and the C=C stretch of tetracyanoethylene at 1551 cm-1, with smaller contributions from other modes localized on both tetracyanoethylene and hexamethylbenzene. The importance of these results for understanding trends in the rates of nonphotochemical return electron transfer is discussed.
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页码:6208 / 6219
页数:12
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