1985 Fiscal Year Final Research Report Summary
Study of quantum fluid by structures in Raman spectra
| Project/Area Number |
59420011
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | Hiroshima University |
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Principal Investigator |
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| Project Period (FY) |
1984 – 1985
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| Keywords | quantum fluid / superfluidity / Raman scattering / 素励起 |
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| Research Abstract |
The purpose of this research is to cralify the microscopic state of the superfluid helium 4 by the observation of laser Raman spectra. Fine structures have been found in the Raman spectra of the superfluid helium under saturated vapor pressure. However, the statistical accuracy of the data was not accurate enough to discuss the functional form in detail. Thus we developped a multi-channel spectrometer and succeeded in increasing accuracies remarkably. With this spectrometer, we re-confirmed the spectral structures of the superfluid helium under saturated vapor pressure at 1.3 K. Next, we measured the pressure dependence of the spectra by controlling the pressures to be 1,3,5,6,10,15, and 20 kg/ <cm^2> .The spectra are characterized by apprearance of three peaks <p_1> , and <p_3> . The fine structures are observed in the energy shift region between <p_1> and <p_2> . Mainly three new aspects have been found: 1) <p_2> splits into two peaks near the pressure of 5 kg/ <cm^2> .2) <p_3> , new
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ly found in this work, becomes clear as the pressure is increased. 3) The fine structures are clearly seen under the pressure up to 10 kg/ <cm^2> . The spectral shape of the fine structures cannot be explained by theories so far proposed. We further extended measurements of the two-roton peak <p_1> with higher accuracies. The peak position has been found to show a pressure dependence different from that of the two-roton energy determined by the neutron scattering. We made comparisons of the experimental spectral shapes with the theoretical model calculations so far believed to be correct, choosing the peak position and the spectral width as the adjustable parameters. We found non negligible discrepancies between them. In the higher energy side of the peak, fine structures are observed. The structure has been found to depend on the applied pressure sensitively. Considering above mentioned new aspects, we calim the spectral structures is a powerful tool to clarify the microscopic condensate state of superfluid helium 4. Less
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