FT-ESR Study of Initial Process of Phtochemical Reactions
Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||KYOTO UNIVERSITY|
HIROTA Noboru Kyoto Univ. Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90093301)
NAKAGAWA Kouichi Fukushima Prefectural Medical College, Assistant, 医学部, 助手 (00244393)
TERAZIMA Masahide Kyoto Univ. Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00188674)
WILLIGEN Hans von Univ. of Massachusetts of Boston, Professor, ボストン校・化学科, 教授
OHARA Keishi Ehime Univ. Faculty of Science, Assistant, 理学部, 助手 (10284390)
WILLIGEN Han マサチューセッツ大学, 化学科(ボストン校), 教授
|Project Period (FY)
Completed(Fiscal Year 1996)
|Budget Amount *help
¥2,700,000 (Direct Cost : ¥2,700,000)
Fiscal Year 1996 : ¥2,700,000 (Direct Cost : ¥2,700,000)
|Keywords||Time-Resolved EPR / CIDEP / xanthone / FT-EPR / Photochemical initial process / Phenotiazine|
At the international symposium on spin and magnetic field effects held in Novosibirsk in August, 1996 Hirota, van Willigen and Ohara discussed the detailed plan of the cooperative work. It was decided that the initial processes of photochemical reactions of xanthone of which a number of unsolved problems exist should be studied by FT-EPR method. Following this discussion, Ohara went to Boston in September to make FT-EPR measurements. In this work he obtained the following results.
1) Emissive polarization found in xanthone/2-propanol is mainly determined by the hydrogen abstraction of xanthone and its mechanism is radical pair mechanism (RPM).
2) The rise of the absorptive polarization observed in xanthone/2-propanol +HィイD22ィエD2O +HCl is very rapid determined by the time -resolution of the spectrometer and the mechanism is likely to be triplet mechanism (TM). However, the intensity of the polarization is very weak.
In November, Hirota made further measurement in Boston and examined the effect of the concentration of HCl on the polarization. It was found that inversion of the polarization of the hydroxypropyl radical from E to A takes place at a relatively low concentration of HCl. Moreover, it was found that the polarization of the xanthone ketyl radical showed an inversion from A to E. It was though that additional transient absorption experiments are needed to clarify the initial processes in the photochemistry of xanthone and work along this line was tried in Kyoto with Prof. van Willigen. However, this work has not been completed yet, and further work will be continued.
In addition to the above work Nakagawa made FT-EPR work on the hydrated electron in the SDS micelle produced by the photoionization of phenothiazine and its derivatives. He obtained detailed information about the phase of the CIDEP signal of the hydrated electron, dynamics of disappearance and quenching of the CIDEP signal of the hydrated electron.
Research Output (15results)