1993 Fiscal Year Final Research Report Summary
Simulation of Defect Processes Induced by Electronic Excitation
| Project/Area Number |
03045026
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | University-to-University Cooperative Research |
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| Research Institution | Nagoya University |
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Principal Investigator |
ITOH Noriaki Faculty of Science, Nagoya University, professor, 理学部, 教授 (90022996)
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| Co-Investigator(Kenkyū-buntansha) |
HEIFETS E. ラトヴィア大学, 固体物理化学研究室, 研究員
PUCHIN V. ラトヴィア大学, 固体物理化学研究室, 研究員
SHLUGER A. ラトヴィア大学, 固体物理化学研究室, 教授
NAKAI Yasuo Faculty of Science, Nagoya University, 理学部, 助教授 (40022719)
TANIMURA Katsumi Faculty of Science, Nagoya University, 理学部, 助教授 (00135328)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Exciton / Lattice relaxation / Defect formation / Electronic excitation / Atomic emission / F center / H center / 断熱ポテンシャルエネルギー曲面 |
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| Research Abstract |
Relaxation of an exciton in the bulk of alkali halides and of an excited F center on the (100) surface of alkali halides are simulated using an ab initio quantum mechanical computer code.
The two-dimensional adiabatic potential energy surfaces (APES) of a F center on the NaCl (100) surface at the ground and excited states, for the perpendicular and parallel motion of an alkali atom neighboring the F center was obtained by optimizing the configuration at the excited state. It is shown that there is a potential barrier for the emission of the alkali atom at the excited state. The height of the barrier and the separation between the APES's for the ground state and excited state are found to be dependent on the direction of the emission. It appears that the emission is induced by the non-radiative transitions from the excited state to the ground state, for which a thermal potential barrier should be overcome. The result of the calculation is in accordance with the recent experimental results obtained in our laboratory.
The optical transition of the self-trapped hole and the H center, both of which consist of the halogen molecular ion, are studied by taking the configuration interaction into account. Without the configuration interaction, both the sigma and pi transition energies of the H center is found to be higher than the corresponding transition energies of the self-trapped hole, because of the smaller halogen-halogen distance. The sigma transition energy is found to be diminished by a relatively large configuration interaction between two sigma polarized transitions, while the pi transition is affected little by the configuration interaction. The result is in accordance with the experimental observation carried out recently in our laboratory.
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