2001 Fiscal Year Final Research Report Summary
Ultrafast Spectroscopy and Interface Femtochemistry of Adsorbed Molecules on a Metal in Liquid
| Project/Area Number |
11450322
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業分析化学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
HARATA Akira Faculty of Matrl. Sci., Kyushu University, Ass. Prof., 大学院・総合理工学研究院, 助教授 (90222231)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIOKA Toshio Faculty of Matrl. Sci., Kyushu University, Research Ass., 大学院・総合理工学研究院, 助手 (60304838)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Electrochemical Interface / Femtochemistry / Ultrafast Spectroscopy / Photothermal Phenomena / Nonradiative Processes / Single Crystalline Gold Electrode / Spectro-Electrochemistry / Energy Transfer in Nano-Space |
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| Research Abstract |
This study aims to clarify main factors dominating interfacial femtochemistry at a sold/liquid interface. We have applied ultrafast transient reflectivity measurements for investigating ultrafast interaction of photoexcited electrons in metal with molecules adsorbed on the metal immersed in liquid solutions. A well-defined surface of Au(111) was investigated in an aqueous solution of perchloric acid or sulfuric acid, under electrochemical potential control and with/without interface modification by alkanethiols having a long alkyl chain of different lengths.
We successfully developed an experimental setup to observe ultrafast transient reflectivity of metal in liquid with a high precision. Transient reflectivity of the Au(111) surface showed rapid decrease followed by rapid increase and a remaining constant offset for an initial 4 picosecond after photoexcitation. Decay rate constants of the rapid reflectivity change ranged from 3 to 10 (1/ps) depending on the interface conditions but there observed no dependence on excitation light intensity. The rapid decay was attributed to electron relaxation by electron-electron and electron phonon couplings, while the constant offset was due to phonon temperature rise.
The transient reflectivity showed small but apparent dependence on electrochemical potential, kind of solute electrolytes in the liquid side, existence of surface modification, and hydrocarbon chain length of the alkanethiol interface modifiers. The experimental results are considered in connection with atomic and molecular structure of the solid/liquid interface. It is concluded that molecules adsorbed on the interface, including water molecules and adsorbed ions, play significant rolls in dominating ultrafast electron relaxation at the liquid/solid interface.
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Research Products
(10 results)
