1997 Fiscal Year Final Research Report Summary
Study of the dynamical process for the surface-molecule interaction using laser-induced desorption
| Project/Area Number |
08454076
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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 |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | University of Electro-Communications |
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Principal Investigator |
MURATA Yoshitada University of Electro-Communications・Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (10080467)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIYASU Nobuo University of Electro-Communications・Faculty of Electro-Communications, Research, 電気通信学部, 助手 (60017415)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Pt (111) / Pt (111)-Ge surface alloy / desorption and adsorption of NOand CO / angular distribution of desorbed molecules / intermdiate excited state / insulator-metal transition / 絶縁体-金属転移 / 吸着分子の束縛並進モード |
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| Research Abstract |
Desorption induced by electronic excitation of NO and CO from transition metals has been studied with a nanosecond-pulsed ultraviolet laser. It was observed that NO and CO are desorbed from Pt while these molecules are not desorbed from Ni and Pd. We have tried to elucidate the origin of this remarkable selectivity.
1. It is essential to study thenature of the intermediate excited state in the desorption process. The velocity dependence of the angular distribution for desorbe NO from Pt (111) is observed. The width of the angular distribution becomes sharper with increasing velocity and is independent of therotational energy. A remarkable velocity dependence was observed and is too large to interprete the experimental result by a simple model. Qualitative result shows that stiffening occurs in the frustrated translation of adsorbed NO in the excited state, in contrast to the frustrated rotation, in which softening occurs.
2. Laser-induced desorption of NO from the surface of a Pt (111)-Ge surface alloy, while CO is not desorbed. The elctronic structure of the alloy and the electronic state of CO adsorbed on this surface were observed by photoelectron spectroscopy. The band width of the alloy is narrower than that of Pt. This result is reasonable. The binding energy of the CO 5sigma state on the alloy is nearly equal to that on Pt (111), while the desorption energy is quite different. This contradictory result can be interpreted by a perturbation model.
3. The 1 monolayr Ge surface on the Pt (111)-Ge surface alloy. The insulator-metal transition on the Ge overlayr was observed by reflection absorption infrared spectroscopy.The band width of the absorption spectrum for C-O stretching vibration of adsorbed CO becomes much broader than that on Pt (111), Pt(111)-Ge and multilayr Ge.
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