1996 Fiscal Year Final Research Report Summary
Exploitation of hish-sensitivity synchrotron-radiation soft-x-ray surfacl-structure analysis methods by means of total-retlection emitted x-ray detection
| Project/Area Number |
07454060
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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 | The University of Tokyo |
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Principal Investigator |
CHTA Toshiaki The University of Tokyo Graduate School of Science Professor, 大学院・理学系研究科, 教授 (80011675)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOYAMA Toshihiko The University of Tokyo Graduate School of Science Associate Professor, 大学院・理学系研究科, 助教授 (20200917)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Total-reflection x-rays / Soft x-ray / Surface XAFS / X-ray standing waves / surtace structure aralysis |
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| Research Abstract |
For the surface strcuture analysis, it is generally of great importance to extract information from surfaces by eliminating intense signals from substrates. Surface XAFS spectroscopy and the x-ray standing-wave method require further exploitation concerning this subject. For instance, soft x-ray regions from Si K to Cl K edges by means of the fluorescence yield method are useful for 3d metal surfaces such as Ni and Cu, while it is impossible for heavier elements due to elastically scattered x rays.
In the polarization-dependent XAFS measurements, both experimental setups of s and p polarizations of incident x rays, and the total-reflection conditions for both setups allow us to perform the experiments. In this situation, however, a whole system of an ultrahigh vacuum chamber should be rotated, this being not practical. In the present study, we employed our previous system without much modification and tried to measure polarization dependent XAFS by applying normal-incidence grazing-emssion for s polarization and total-reflection-incidence normal-emission modes. Consequently, S K-edge XAFS spectra of Sadsorbed (less than 0.2 ML) Pd surfaces were successfully obtained. For s polarization, the fluorescence intensity in the total-reflection emission condition was found to be a little too low, and hence the solid angle was required to be enlarged compared to the complete total-reflection mode.
We investigated SO_2 and C_4H_4S on Pd (100) and Pd (111), whose surface structures were found to be noticeably different from those corresponding to the Ni and Cu surfaces studied previously. This successfully demonstrates the usefulness of the present experimental technique.
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