Quantitative investigation for ion-induced nucleation under non-equilibrium conditions of association/dissociation reactions: experimental approaches for elementary formation processes

2015 Fiscal Year Final Research Report

• Project/Area Number: 25287148
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Geochemistry/Cosmochemistry
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: NAKAI Yoichi 国立研究開発法人理化学研究所, 仁科加速器研究センター, 専任研究員 (30260194)
• Co-Investigator(Kenkyū-buntansha): WATANABE Naoki 北海道大学, 低温科学研究所, 教授 (50271531)
• Co-Investigator(Renkei-kenkyūsha): KOJIMA Takao 国立研究開発法人理化学研究所, 仁科加速器研究センター, 専任研究員 (90211896) ; HIDAKA Hiroshi 北海道大学, 低温科学研究所, 助教 (00400010)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: クラスターイオン / 大気イオン化学 / 微粒子核生成 / 原子分子物理

Outline of Final Research Achievements

We performed stable and precise measurements compared with previous studies for Gibbs free energy changes of stepwise association reactions of a water molecule to H3O+(H2O)n ions using a ion drift tube with a selected ion injection. Furthermore, an empirical effective temperature of the reaction equilibrium constants was obtained for association/dissociation reactions of a water molecule to/from　H3O+(H2O)n ions in a pure water vapor. The effective temperature means a representative physical quantity of collision energy influenced by an electric field. It was found that a new parameter describing electric field dependence of the effective temperature presumably reflects structures of H3O+(H2O)n ions. We also performed R&D of ion handling methods in an RF ion trap, such as an ion mass selection, in order to make use of RF ion traps for cluster formation experiments.

Free Research Field

原子分子科学、放射線物理学