Studies on Lattice Vibrations of Dielectric and Magnetic Crystals by Hyper-Raman Scattering.
| Project/Area Number |
58430005
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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 |
構造化学
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
1983 – 1985
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| Project Status |
Completed (Fiscal Year 1985)
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| Budget Amount *help |
¥40,100,000 (Direct Cost: ¥40,100,000)
Fiscal Year 1985: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1984: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 1983: ¥34,000,000 (Direct Cost: ¥34,000,000)
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| Keywords | hyper-Raman spectrum / Q-switched Nd:YAG laser / polychromator / photodiode array detector / multichannel detection / SrTi <O_3> / CsCa <Cl_3> |
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| Research Abstract |
The experimental arrangement set up for the measurement of the.hyper-Raman spectrum is as follows.
The 1.06 <micro> m line from an acousto-optically Q-switched Nd:YAG laser (NEC) was used for the excitation. The repetition rate was set to between 2 KHz (pulse width 150 ns) and 6 KHz (200 ns). A peak power between 3 and 50 KW was employed. The laser beam was focussed into the sample by a f = 5.cm lens. The scattered light in the 90゜ geometry was dispersed by a polychromator (JASCO TRS-501) and detected by the intensified photodiode array detector (Tracor Northern) with a controller. In this multichannel detection system the frequency region of approximately 230 <cm^(-1)> is measured simultaneously.
In the hyper-Raman spectrum below 280 <cm^(-1)> of SrTi <O_3> crystal. three bands at 88, 175 and 266 <cm^(-1)> are observed, which correspond to the <nu_1> (TO, <f_(1u)> ), <nu_1> (LO, <f_(1u)> ) + <nu_2> (TO, <f_(1u)> ) and <nu_4> ( <f_(2u)> ) respectively. These bands were used for the adjustment and wavenumber calibration of our spectrometer.
In CsCa <C1_3> , the following five hyper-Raman bands were observed: 76 <cm^(-1)> ( <nu_1> LO), 114 <cm^(-1)> ( <nu_2> TO), 142 <cm^(-1)> ( <nu_2> LO), 267 <cm^(-1)> ( <nu_3> TO) and 312 <cm^(-1)> ( <nu_3> LO). These are compared with the data obtained from the far-infrared reflection spectrum and a Kramers-Kroning analysis. The hyper-Raman data might be more reliable than the far-infrared data, because (1) the reflectivity measurements depend on the condition of the crystal surface and (2) the data in the low-reflectivity region influence the accuracy of the dielectric function and the TO and LO frequencies calculated from relectivity data by Kramers-Kronig relation.
The hyper-Raman spectra of several alkali halides and perovskite chlorides were measured.
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Research Products
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