2000 Fiscal Year Final Research Report Summary
Determination of chemical shape and the propensity rule on channel branching by active control of quantum state
| Project/Area Number |
10440174
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
OHYAMA Hiroshi Graduate school of science, Osaka University, Associate Professor, 大学院・理学研究科, 助教授 (60192522)
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| Project Period (FY) |
1998 – 2000
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| Keywords | velocity selected steric opacity function / Penning ionization / Feshbach resonance |
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| Research Abstract |
A new technique for generating matastable beam was performed by using the pseudo-random pulsed glow discharge method. By using this technique combined with the oriented molecular beam technique, stereo-dynamics in the penning ionization was studied for some reaction systems in order to reveal the propensity rule on the branching into each channel.
Collision energy dependence of the ionization cross section for the Ar(^3P) + CH_3Cl→Ar + CH_3Cl^+ + e^- reaction was determined under specific relative orientation using an oriented CH_3Cl beam and time-of-flight measurements. A good correlation between the steric opacity function and the spatial distribution of the electron for the relatedmolecular orbital is recognized at the low collision energy region. On the other hand, steric opacity functions give the remarkable oscillation structure as the collision energy increase. This collision energy dependence is extremely different from the propensity rule based on the anisotropy of the interaction potential. We propose that this discrepancy can be ascribed to the dependent competition of product branching between Penning ionization and neutral dissociation varies as collision energy. In addition, the remarkable resonance structure is revealed in the energy dependence of orientation angle-resolved cross section. The resonance-type structure could be interpreted as a "nuclear-excited Feshbach resonance" in the formation of vibrational excited Rydberg states leading to a competitive dissociative exit channel.
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