High sensitivity millimeter-wave spectrometer using the millimeter wave resonator. High sensitivity detection of the transient species.
| Project/Area Number |
16550018
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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 |
Physical chemistry
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
HARADA Kensuke Kyushu Univesity, Chemistry, Research associate, 理学研究院, 助手 (70165017)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Keiichi Kyushu University, Chemistry, Associate professor, 理学研究院, 助教授 (50037280)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | millimeter wave resonator / molecular complex / H_2-HCN / intermolecular vibration / FT microwave spectrometer / millimeter wave spectroscopy / CoNO / photolysis / フーリエ変換マイクロ波分光 / ラジカル錯体 / 超高速ジェット |
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| Research Abstract |
High sensitivity millimeter wave spectrometer using the millimeter wave resonator has been developed and applied to the detection of the transient species. The main reflectors of the resonator are the spherical mirrors with the diameter of 130 mm and the radius of curvature of 600 mm. The cavity length is 600 mm. These mirrors are placed in the vacuum chamber, which is evacuated by the 10 inch diffusion pump. One of the mirror is placed on the tunable x-stage actuated by the pulse motor controlled by the personal computer. The thin plastic film is used as a beam splitter and placed inside the resonant cavity. The input millimeter wave is partially reflected by the beam splitter and resonated inside the cavity. The output of the resonator reflected by the beam splitter is detected by the InSb detector. The supersonic jet nozzle for the electrical discharge or laser photolysis is placed just above the focus of the resonant millimeter wave beam. The advantages of the present method are as
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follows. The narrow region near to the supersonic jet nozzle, where high concentration of the transient species are expected, is observed with the millimeter wave resonator. The high reflectivity of the mirror is easily obtained in the millimeter wave region. The thin plastic film is available and usable as a beam splitter, because of the good transmittance in the millimeter wave region. Because of these reason, the reflection type resonator has rather good performance in the millimeter wave region. The vibrational noise of the pumping system using the diffusion pump is small enough. The performance of the millimeter wave resonator, thus constructed, was measured. The Q value of the resonator was 355 and the output efficiency of the resonator was 80%, from which the 284 times sensitivity is obtainable essentially in comparison with the single path absorption detection. When we applied the resonator to the detection of the molecular complex such as H_2-HCN, the vibrational noise of the beam splitter generated by the pressure of the supersonic jet pulse was a serious problem. The several noise reduction improvements are now in progress. The Fourier transform microwave (FTMW) spectrometer was also assembled in the vacuum chamber perpendicular to the millimeter wave resonator and the supersonic jet pulse. The tuning of the spectrometer is now in progress.
The H_2-HCN complex is a weakly bonded molecular complex including molecular hydrogen. The hydrogen molecule attaches to the nitrogen end of HCN for (ortho)H_2-NCH, while to the hydrogen end for (para)H_2-HCN in the ground state according to the MMW study of the pure rotational transitions of H_2-HCN. In the present study, we have observed the Σ_1-Σ_0 band of the j_<HCN>=1-0 internal rotation band of (ortho)H_2-HCN. The band origin of the Σ_1-Σ_0 band has been determined to be 149.8 GHz. The internal rotation bands of Ne-HCN have been also observed and assigned. The rotational spectrum of CoNO generated by UV laser photolysis of Co(CO)_3NO has been observed in the millimeter wave region. Less
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Report
(3 results)
Research Products
(2 results)
