2000 Fiscal Year Final Research Report Summary
Optical Properties of Chalcogen under High Pressure
| Project/Area Number |
11640304
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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 |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Hirosaki University |
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Principal Investigator |
YAMAMOTO Itsuro Hirosaki University, Faculty of Education, Assistant Professor, 教育学部, 助教授 (40210520)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Chalcogen / Selenium (Se) / Selenium Cluster / Arsenic Chalcogenide / As-Se Mixture / As-Te Mixture |
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| Research Abstract |
Chalcogen such as selenium (Se), tellurium (Te) and sulphur (S) is composed of polymeric chain or ring molecules connected by twofold coordinated covalent bonds. It has much crystalline polymorphism and is semiconductor at atmospheric pressure and room temperature. It is known that chalcogen has a wide variety of structural and electrical properties by changing pressure and temperature. Under high pressure it undergoes the semiconductor to metal transition and shows metallic behavior.
In this study we discuss how the electronic properties in various states of chalcogen are related to the atomic configuration. This study is classified as follows.
(a) Optical properties of chalcogen under high pressure.
(b) Study of chalcogen clusters.
(c) Study of arsenic chalcogenide mixtures.
In (a) we have measured reflectivity spectra of Se at pressures up to 16GPa using a diamond anvil cell. The electronic states of the metallic phase have been discussed.
In (b) Se clusters have been produced in the free space. Their X-ray absorption near edge structure (XANES) and photoelectron photoion coincidence (PEPICO) spectra have been measured in situ on the Se K-edge by utilizing synchrotron radiation in Photon Factory, KEK.The size dependence and de-excitation process of Se clusters have been discussed.
In (c) X-ray absorption fine structure (XAFS) and dc conductivity in the liquid and glassy states of As-Se and As-Te mixtures have been measured. The relation of their local structure and electronic states has been discussed.
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