2004 Fiscal Year Final Research Report Summary
Relaxation Dynamics of Polyatomic Molecules Studied by Site-Selective Excitation of K-Shell Electrons
| Project/Area Number |
14540471
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Kyoto University of Education |
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Principal Investigator |
IBUKI Toshio Kyoto University of Education, Department of Chemistry, Professor, 教育学部, 教授 (30027065)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Soft X-ray photochemistry / Site-specific fragmentation / K-shell excitation / Kinetic energy distribution / Auger process |
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| Research Abstract |
One of the attractive topics in inner-shell excited polyatomic molecules has been a site-selective bond dissociation or "photon-scissors" to cut a specific chemical bond following Auger electron emission. Typical decay time of the Auger process is in the order of 10^<-15> s is shorter than the periods of molecular vibrations and rotations in 10^<-14>-10^<-11> s. Thus, the bond dissociation initiated by the Auger process is expected to occur in a limited area of the molecule. However, the site-specific reaction has not been always observed decidedly in gas phase molecules. In the present work, we measured that the site-dependent fragmentation competes with intramolecular
energy relaxation in the C, F and/or O K-shell excited CF_3COCH_3,CF_3CCH and CF_2CH_2. Then we showed that the intramolecular energy relaxation observed makes the site-selectivity vague. The effective distance in a molecule for the energy relaxation was estimated to be about 1 nm (10^<-9> m) by changing molecular lengths and by selectively exciting the N and O K-shell electrons in a series of CH_3CO(CH_2)_nCN(n=0-4).
We observed that the C and F K-shell excitation in CF_3SF_5, which has been found for the first time in 1999 to be a strong greenhouse gas, results in a small site-specific photofragmentation. The S1s electron excitation at hν=2484 eV gives a huge site-selectivity, probably being due to a cascade Auger electron emission in L-shells. This finding suggests that an atom in the third row of the periodical table would effectively work for the site-specific fragmentation in the K-shell excited polyatomic molecule.
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Research Products
(12 results)
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[Journal Article] Vibrational effect on the fragmentation dynamics of the C K-shell excited CF_2CH_22005
Author(s)
K.Okada, Y.Yamana, T.Ibuki, A.Fujii, S.Nagaoka, T.Tabayashi, Y.Shimada, Y.Morishita, Y.Tamenori, I.H.Suzuki, K.Ohno
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Journal Title
J.Electron Spectrosc.Rel.Phenom. (in press)
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Total photoabsorption cross-sections of CF_3SF_5 in the C, F and S K-shell regions2004
Author(s)
T.Ibuki, Y.Shimada, S.Nagaoka, A.Fujii, M.Hino, T.Kakiuchi, K.Okada, K.Tabayashi, T.Matsudo, Y.Yamana, I.H.Suzuki, Y.Tamenori
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Journal Title
Chem.Phys.Lett. 392
Pages: 303-308
Description
「研究成果報告書概要(欧文)」より
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