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Studies on Lattice Vibrations of Dielectric and Magnetic Crystals by Hyper-Raman Scattering.

通过超拉曼散射研究介电和磁性晶体的晶格振动。

基本信息

批准号：
58430005
负责人：
NAKAGAWA Ichiro
金额：
$ 25.66万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1983
资助国家：
日本
起止时间：
1983 至 1985
项目状态：
已结题

项目摘要

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.

超喇曼光谱测量的实验装置如下：<micro>用声光调Q Nd：YAG激光器（NEC）的1.06 μ m谱线激发。重复率被设置为在2KHz（脉冲宽度150 ns）和6 KHz（200 ns）之间。采用3和50 KW之间的峰值功率。激光束通过f = 5.cm透镜聚焦到样品中。在90 nm几何形状中的散射光由多色仪（JASCO TRS-501）分散，并由具有控制器的增强型光电二极管阵列检测器（Tracor北方）检测。在该多通道探测系统中，同时测量了SrTi晶体280 cm ^（-1）以下的超拉曼光谱，测量频率范围约为230 cm^（-1）<O_3>。在88、175和266 cm^（-1）处观察到三个谱带，分别对应于<nu_1>（TO，<f_（1u）>）、<nu_1>（LO，<f_（1u）>）+<nu_2>（TO，<f_（1u）>）和<nu_4>（<f_（2u）>）。在CsCa中<C1_3>，观察到以下五个超拉曼谱带：76 cm^（-1）>（<nu_1>LO），114 cm^（-1）>（<nu_2>TO），142 cm ^（-1）>（<nu_2>LO），267 cm ^（-1）>（<nu_3>TO）和312 cm^（-1）>（<nu_3>LO）。这些是从远红外反射光谱和Kramers-Kroning分析得到的数据进行比较。超拉曼光谱数据可能比远红外光谱数据更可靠，因为（1）反射率的测量依赖于晶体表面的条件，（2）低反射率区的数据影响介电函数和由Kramers-Kronig关系式计算的TO和LO频率的准确性。