MgF_2单晶的THz光谱研究  

THz spectra study of MgF_2 crystals

作　　者：侯碧辉[1] 邵萌[1] 徐新龙[2] 汪力[2] 王吉有[1] 范志达 

机构地区：[1]北京工业大学应用数理学院,北京100022 [2]中国科学院物理研究所光物理国家实验室,北京100080 [3]人工晶体研究院,北京100018

出　　处：《物理学报》2007年第3期1370-1374,共5页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10390160和39890390)资助的课题.~~

摘　　要：利用THz时域光谱技术对MgF2晶体(样品1)和MgF2:Co晶体(样品2)在0.5—2.5THz的吸收特性进行了研究.在0.5—2.5THz波段,样品1吸收系数α(ν)随频率ν增加而增大,最大值为24cm-1.样品2的吸收系数比样品1大得多,Co掺杂使晶格吸收带边向低频移动,而且样品2在1.9THz有吸收峰,吸收系数达到70cm-1,由此求出F--Co2+离子键伸缩振动的键力常数K为3.40×10-2N/cm.这一结果表明,THz光谱分析有可能成为研究晶体化学键的一种重要手段.利用光学常数之间的关系计算了两个样品在0.5—2.5THz的介电函数的实部ε1(ν),得到样品1的ε1(ν)值在4.67至4.73之间,样品2的ε1(ν)值在4.62至5.01之间.THz （terabertz） properties of MgF2 crystal （sample 1） and MgF2： Co crystal （sample 2） is measured using transmission THz time domain spectroscopy in the frequency range between 0.5 and 2.5 THz. The absorption coefficients α （v） of sample 1 increases and has a maximum 24cm^-1 with increasing frequency v from 0.5 THz to 2.5 THz. The absorption coefficient of sample 2 is much larger than that of the sample 1, and its absorption band edge of the crystal lattice shifts to lower frequency side because of the dopant Co. Moreover, there is an absorption peak at 1.9THz and the absorption coefficient is greater than 70 cm^- 1 , the force constant K of F^- -Co^2 ＋ ionic chemical bond stretch vibration calculated from this peak is 3.40 × 10^- 2 N/cm. The THz spectroscopy can be an important technique for research of chemical bond in crystal. Real dielectric functions between 0.5 and 2.5 THz of the two samples are calculated by relations between optical constants. The ε1 （v） of sample 1 varies from 4.67 to 4.73 and ε1 （v） of sample 2 varies from 4.62 to 5.01.

关 键 词：THZ辐射 光谱 MgF2晶体 吸收特性 

分 类 号：O433[机械工程—光学工程]