1993 Fiscal Year Final Research Report Summary
Development of high resolution photoelectron spectroscopy by using higher Rydberg state and spectroscopy of cations
| Project/Area Number |
04453013
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
構造化学
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| Research Institution | School of Science and Engineering, Waseda University (1993)
Tohoku University (1992) |
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Principal Investigator |
FUJII Masaaki School of Science and Engineering, Waseda University, Associate Professor, 理工学部, 助教授 (60181319)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Mitsuo Institute for Molecular Science, Director General, 所長 (20013469)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Photoelectron Spectroscopy / Electronic Spectrum In Gas / Multiphoton Process / Rydberg State |
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| Research Abstract |
High resolution photoelectron spectroscopy by using high Rydberg state has been developed. Resolution of 0.6meV(5cm-1)has been achieved. This resolution is 100 times higher than that of traditional photoelectron spectroscopy. This new spectroscopy can be achieved simply by connecting a home made pulse generator to an usual vacuum chamber for MPI spectroscopy. No special equipment, such as magnetic shield, has been used. It is because this spectroscopy detects field ionization signal of higher Rydberg state instead of photoelectron. The Rydberg molecule is insensitive to an external field therefore the experimental setup can be simplified extremely.
We applied this technique to diazabicyclooctane, o-, m-, and p-fluorotoluenes, 1,2,4,5-tetrafluorobenzene, and p-defluorobenzene. Well-resolved vibrational structures of cations have been observed. In special, internal rotational levels of methyl groups in fluorotoluene cations have been analyzed and potential curves have been determined. The analysis has revealed great increase of the barrier height of the internal rotation after ionization. From the good correlation between the increase of the barrier height and the decrease of internal rotational constant, it is concluded that the increase of the barrier is due to geometrical change after ionization.
We have also found polarization effect in this spectroscopy. The band intensity in the spectrum changes drastically when the polarization of the exciting light changes from linear to circular. The change in band intensity correlates with the symmetry of the vibrational level in the cation. It shows that the polarization effect of this spectroscopy is useful to assign the vibrational symmetry of the molecular cation.
In conclusion, we have established the new high resolution photoelectron spectroscopy by using higher Rydberg state with a simple experimental setup. It will be a powerful tool to study a large molecular cation.
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