Charge Transfer and Dissociation Reactions of Cluster lons

1990 Fiscal Year Final Research Report Summary

• Project/Area Number: 01540320
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 物理学一般
• Research Institution: Rikkyo University
• Principal Investigator: KOIZUMI Tetsuo Rikkyo University, College of Science, Associate Professor, 理学部, 助教授 (90147926)
• Project Period (FY): 1989 – 1990
• Keywords: Charge Transfer Reaction / De-excitation Reaction / Ion Swarm / Cluster Formation

Research Abstract

State-selective ion molecular reactions were studied with an injected-ion drift tube mass spectrometer, whose drift tube can be cooled with liquid nitrogen. The rate coefficients of one-electron capture reaction in the systems Kr^<2+>+Ne, Kr^<2+>+H_2, Kr^<2+>+N_2, Kr^<2+>+O_2, Kr^<2+>+CO, and Kr^<2+>+NO were measured in the energy range from 10 to 60 meV. It was found that a large difference exists in the absolute magnitudes of reaction rate according to the electronic states of Kr^<2+> ion. For example, the reaction Kr^<2+>(^3P_2)+N_2 has a large reaction rate of 10^<-9> cm^3/sec at 14 meV, while the reaction Kr^<2+>(^3P_0+N_2 is almost immeasurable. These results can be explained by the potential curve crossing model.
In the case of Kr^<2+>+He system, a spin changing de-excitation reaction
Kr^<2+>(^1D) + He -> Kr^<2+>(^3P_1) + He
was observed. The rate of this reaction was obtained as (6.9<plus-minus>1.0)x10^<-11> cm^3/sec at 12 meV. No one-electron capture was detected for this system. These results cannot be explained by the curve crossing model. The true mechanism of this de-excitation reaction is not clear, theoretical investigations are awaited.
The drift tube was also used for the study of cluster ion formation reaction of N_2^+ ions with N_2. The clusters (N_2)_n^+ for n=2-9 were observed in this study. It was found that the cluster (N_2)_n^+ has stable shell structures at n=3, 4, 6, and 9.