| Project/Area Number |
17205003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | Okayama University |
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Principal Investigator |
JIAN Tang Okayama University, Graduate School of Natural Science and Technology, Associate Professor (40379706)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥45,110,000 (Direct Cost: ¥34,700,000、Indirect Cost: ¥10,410,000)
Fiscal Year 2007: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2006: ¥6,110,000 (Direct Cost: ¥4,700,000、Indirect Cost: ¥1,410,000)
Fiscal Year 2005: ¥36,660,000 (Direct Cost: ¥28,200,000、Indirect Cost: ¥8,460,000)
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| Keywords | Molecular spectroscopy / Vibration-rotation spectrum / Supersonic molecular beam / Infrared cw-OPO laser / Cavity ringdown spectroscopy / AOM pulsing / Hydrogen Cluster / Molecular superfluidity / キャビティリングダウン / 分子分光 / 回転温度 / 分子の振動回転スペクトル / 超流動 / ファンデルワールス分子錯体 / 高分解能分光 |
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| Research Abstract |
Helium is the only known element which can exist in the state of superfluidity, and hydrogen molecule is the only natural candidate for superfluidity. In similar to studies for the helium clusters with molecules, the superfluidity of hydrogen molecule may be revealed by study of infrared spectroscopy of hydrogen molecular clusters in gas phase. In the present study, we observed the vibrational-rotational spectra of (para-H_2) N-N_2O and (ortho-H_2)NN_2O clusters up to N=13. The analysis of the rotational constants for the (para-H_2)NN_2O clusters showed that the rotational constants decrease monetarily with the increase of N up to N = 13, and no evidence shows up for the setup of hydrogen molecular superfluidity. For N larger than 15, the spectrum pattern of (para-H_2)N-N_O becomes irregular suddenly, which may be considered as the sign of the setup for hydrogen molecular superfluidity.
In order to study more species of hydrogen clusters, we installed a cw-OPO laser (Linos OS4500) opera
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ted in the infrared region of 1.38-2.00 um and 2.28-4.67 pm and set up an infrared absorption spectrometer equipped with a pulsed supersonic expansion and an astigmatic multiple pass (238 times) absorption cell. Initially, two simultaneous chopping modulations with different frequencies were used to suppress the output fluctuation of OPO laser by taking the signal ratio of the two detection paths with and without absorption. Later, a cavity ringdown spectrometer was built to reach higher sensitivity for detection of the hydrogen molecular clusters. Since the sensitivity of cavity ringdown spectroscopy is not affected by the power change of light source, the problem of the output fluctuation of OPO laser can be avoided ideally. We observed the very weak rovibratational transitions of methane and found that the detectable minimum absorption coefficient is 1× 10^<-7> cm^<-1> when the frequency of the OPO laser is not tuned. The spectra of the hydrogen molecular clusters should be observed with further improvement of the sensitivity. Less
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