硫氰酸镉锌晶体的振动光谱和结构  

Vibrational Spectra and Structure of ZnCd(SCN)_4 Single Crystal

作　　者：刘伟良[1] 夏海瑞[1] 王新强[2] 许东[2] 

机构地区：[1]山东大学物理与微电子学院,济南250100 [2]山东大学晶体材料国家重点实验室

出　　处：《光散射学报》2004年第1期21-26,共6页The Journal of Light Scattering

基　　金：国家自然科学基金(No.10274043;No.50272037);国家863项目(2002AA313070);山东省自然科学基金(No.Y2001A06);攻关项目(No.012120105);山东大学晶体材料国家重点实验室赞助

摘　　要：本文通过对硫氰酸镉锌(ZnCd(SCN)4,简称ZCTC)晶体的群论、拉曼光谱分析和理论计算发现,对于具有I4对称性的ZCTC,在结构中具有ZnN4、CdS4畸变四面体,ZnN4与CdS4由电子桥-N=C=S-联结构成三维骨架的空间无限延伸的结构网络,畸变四面体产生的偶极矩通过电子桥传递,微观偶极矩通过电子桥-N=C=S-相互叠加,且方向一致,从而使宏观晶体材料显示出大的非线性效应。The vibrational spectra of the zinc cadmium thiocyanate (ZCTC) single crystal are studied by Raman spectroscopy and ab initio calculation with the Molecular Orbital (MO) theory using a GAUSSIAN 98 program. Agreement is achieved between the vibrational frequencies predicted by the theory and those observed in Raman scattering experiments. The results show that the characteristic vibrational modes of ZCTC crystal arise mainly from the internal vibrations of the SCN, Zn(NCS)_4, and Cd(SCN)_4 clusters. The three-dimensional network structure of ZCTC crystal is identified, and the highly optical nonlinearities of the crystals are chiefly ascribed to the distorted Zn(NCS)_4 and Cd(SCN)_4 tetrahedra and the conjugated charge-transfer (-Zn-NCS-Cd-) bridges that connect all the distorted tetrahedra together.

关 键 词：硫氰酸镉锌晶体 非线性光学晶体 拉曼光谱 分子轨道理论 电子桥 微观偶极矩 

分 类 号：O734.1[理学—晶体学]