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.

用于测量超拉曼光谱的实验设置如下。来自声光Q开关Nd:YAG激光器(NEC)的1.06微米线用于激发重复率。设置为 2 KHz（脉冲宽度 150 ns）和 6 KHz（200 ns）之间，采用 3 至 50 KW 之间的峰值功率。通过 f = 5.cm 透镜将散射光聚焦到样品中，并通过多色仪 (JASCO TRS-501) 进行分散，并通过带有控制器的增强型光电二极管阵列检测器 (Tracor Northern) 进行检测。多通道检测系统同时测量大约 230 <cm^(-1)> 的频率区域。在低于 280 <cm^(-1)> 的超拉曼光谱中SrTi <O_3> 晶体在 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)> ) 这些波段分别用于在 CsCa <C1_3> 中，观察到以下 5 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)。将这些数据与从远红外反射光谱和 Kramers-Kroning 分析获得的数据进行比较。超拉曼数据可能比远红外数据更可靠。 - 红外数据，因为 (1) 反射率测量取决于晶体表面的状况，并且 (2) 低反射率区域中的数据影响介电函数以及计算得出的 TO 和 LO 频率的精度测量了几种碱金属卤化物和钙钛矿氯化物的超拉曼光谱。