EPR investigation of the free radicals generated during the photosensitization of TiO2 colloid by hypocrellin B

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	EPR investigation of the free radicals generated during the photosensitization of TiO2 colloid by hypocrellin B
	Wu, T; Xu, SJ; Shen, JQ; Chen, S; Zhang, MH; Shen, T
刊名	FREE RADICAL RESEARCH
	2001
卷号	35 期号:2 页码:137-143
关键词	Natural Pigment Titanium Dioxide Colloid Electron Injection Cation Radical Spin Elimination
ISSN号	1071-5762
英文摘要	The cation radical of dye produced from the interfacial electron transfer from a surface chelated dye to the conduction band of the colloidal TiO2 was studied by laser flash photolysis and electron paramagnetic resonance (EPR) techniques. The study employed hypocrellin B (HB), a natural photodynamic pigment with strong absorption over the visible light region, as a sensitizer and titanium dioxide as a colloid semiconductor. HB formed a chelate with this colloid semiconductor and exhibited a red-shifted and strongly enhanced absorption in the visible spectrum. Laser photolysis indicated that the electron excitation in the visible absorption band of the chelate resulted in extremely rapid and efficient electron injection from the excited triplet state of the dye into the conduction band of the semiconductor. A transient absorption of cation radical of HB at 570 run was observed. The appearance of cation radical of HB was characterized by EPR spectrometry: the photoinduced EPR signal was not quenched by oxygen and its intensity decreased in the presence of NaI, a typical hole scavenger. The generation of conduction band electrons in HB-sensitized TiO2 system was also verified by the spin elimination of a stable cyclic nitroxide, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), and by the reduction of methyl viologen (MV2+) to its radical MV+..
语种	英语
出版者	HARWOOD ACAD PUBL GMBH
WOS记录号	WOS:000170220100006
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/77475]
专题	中国科学院化学研究所
通讯作者	Zhang, MH
作者单位	Chinese Acad Sci, Inst Chem, Ctr Mol Sci, Beijing 100080, Peoples R China
推荐引用方式 GB/T 7714	Wu, T,Xu, SJ,Shen, JQ,et al. EPR investigation of the free radicals generated during the photosensitization of TiO2 colloid by hypocrellin B[J]. FREE RADICAL RESEARCH,2001,35(2):137-143.
APA	Wu, T,Xu, SJ,Shen, JQ,Chen, S,Zhang, MH,&Shen, T.(2001).EPR investigation of the free radicals generated during the photosensitization of TiO2 colloid by hypocrellin B.FREE RADICAL RESEARCH,35(2),137-143.
MLA	Wu, T,et al."EPR investigation of the free radicals generated during the photosensitization of TiO2 colloid by hypocrellin B".FREE RADICAL RESEARCH 35.2(2001):137-143.