2004 Fiscal Year Final Research Report Summary
Collision processes of singly and multiply charged ions in cold helium gas
| Project/Area Number |
15540388
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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 |
原子・分子・量子エレクトロニクス・プラズマ
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| Research Institution | RIKEN |
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Principal Investigator |
MATSUO Yukari RIKEN, Heavy Nuclear Ion Physics Laboratory, Senior Research Scientist, 本林重イオン核物理研究室, 先任研究員 (50231593)
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| Co-Investigator(Kenkyū-buntansha) |
MORIWAKI Yoshiki Toyama University, Faculty of Science, Associate Professor, 理学部, 助教授 (90270470)
FUKUYAMA Yoshimitsu RIKEN, Heavy Nuclear Ion Physics Laboratory, Contract Researcher, 本林重イオン核物理研究室, 協力研究員 (20332249)
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| Project Period (FY) |
2003 – 2004
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| Keywords | ion-atom collision / exciplex / cold helium gas / laser-induced fluorescence / sensitized fluorescence / laser ablation / three-body collision |
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| Research Abstract |
We are aiming at studying electronic energy transfer of singly and multiply charged ions in collision with cold helium gas at 3-300K. Although pair-potentials between helium atom and other atomic species are relatively well known among other interatomic potentials, experimental studies of collisions between cold helium atoms and other atoms are scarce. Moreover, only a few collision cross sections are measured for the combination of helium atom and atomic ions even at room temperature. This is presumably because of the difficulty of producing atomic ions in the environment of cold helium gas. In order to solve the problem, we applied laser ablation technique to a solid sample in cold helium gas to produce atomic ions and detected them with laser-spectroscopic method. The results will leads to the information on interatomic potentials between ions and atoms.
Produced ions are excited to the electronically excited state with a tunable dye laser, then both laser-induced fluorescence (LIF) from ions in the excited state and sensitized fluorescence (SF) from ions in the state to which ions are transferred by collision with helium atoms are observed simultaneously. This procedure makes it possible to determine collision cross sections of ions and cold helium atoms. In particular, alkali-earth ions such as Ba^+ reveal fascinating character of forming molecules called exciplex (e.g. Ba^<+*>-He) in high density cold helium gas due to the three-body collision of excited ions and two helium atoms. Another two-body collision process of such exciplex and helium atoms results in dissociation of Ba^<+*>-He into Ba^+ ion and helium atom. We have clarified a peculiar temperature dependence of cross sections caused by two- and three-body collisions at temperature 3-30 K for the first time.
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