LiB3O5晶体946nm,473nm倍频增透膜的研制

采用离子辅助沉积技术在LiB3O5晶体上制备了946nm,473nm倍频增透膜,并测量了薄膜的性质.测试结果表明, 该增透膜具有较低的剩余反射、高的环境稳定性和良好的附着力.进一步测量了薄膜在波长1064nm多脉冲辐照下的激光损伤阈值,获得了两种不同的损伤形貌,并对损伤原因作了初步的探讨.此工艺下镀制的LiB3O5晶体用于瓦级全固态蓝光激光器,获得了3.8W波长为473nm的连续蓝光输出.     

四方相BaTiO_3及BaTiO_3∶Ce的拉曼散射特性研究

本文报道了在室温下ＢａＴｉＯ３及ＢａＴｉＯ３：Ｃｅ的拉曼谱的特点，着重讨论了前向散射配置下两个１Ｉ（ＴＯ）模（位于２７５ｃｍ－１和５１６ｃｍ－１左右）出现在Ａ１（ＴＯ）谱中的原因。通过设计特别的前向散射实验得到了此配置下由于晶体出射面对入射光的反射造成的背向散射的强度。在ＢａＴｉＯ３的前向散射谱中扣除了背向散射信号后，两个宽峰基本减掉，而掺Ｃｅ后经同样扣除背向散射信号两宽峰却依然很强。这样便证明了它们在前向散射中的出现与杂质有关系。在ＢａＴｉＯ３扣除背向散射后的谱中，还首次观察到一个位于４９２ｃｍ－１的峰。掺Ｃｅ后晶体的吸收曲线有很大变化，本文还讨论了吸收对散射强度的影响。     

Pseudogap and Superconducting Gap in SmFeAs（O1-xFx） Superconductor from Photoemission Spectroscopy

High resolution photoemission measurements are carried out on non-superconducting SmOFeAs paxent compound and superconducting SmFeAs（O1-xFx） （x = 0.12, and 0.15） compounds. The momentum-integrated spectra exhibit a clear Fermi cutoff that shows little leading-edge shift in the superconducting state. A robust feature at 13 meV is identified in all these samples. Spectral weight suppression near IF, F with decreasing temperature is observed in both undoped and doped samples that points to a possible existence of a pseudogap in these Fe-based compounds.     

INFLUENCE OF γ-RADIATION ON THE DIELECTRIC CHARACTERISTICS IN Rb2ZnCl4 SINGLE CRYSTALS AT INCOMMENSURATE-COMMENSURATE PHASE TRANSITION

In this paper the influence of γ-radiation on the dielectric constants of Rb₂ZnCl₄ crystal at incommensurate-commensurate phase transition (hereafter abbreviated as INC-C transition) are studied. The thermal hysteresis occurs upon both cooling and heating runs, irrespective of whether the samples have been treated with γ-radiation or not. For the γ-irradiated sample, its transition point, T_c, between the INC and C phases is not changed, but the peak value of the dielectric constant at T_c increases abruptly, compared with that before γ-irradiation, When this sample is annealed at 40℃, the peak value restores to the incipient value for the sample free from γ-irradiation. The origin of the phenomenon of the thermal hysteresis of the dielectric constant may be due to the pinning effect of dejects or impurities in the samples.     

BaTiO3和Ce:BaTiO3晶体极性声子和电磁激元的喇曼散射研究

从声子-电磁激元频率色散关系的普遍公式出发,推导出了单轴晶体的Merten方程和电磁激元的频率色散关系。测量了BaTiO₃和Ce:BaTiO₃晶体的简正模和斜声子的喇曼散射谱,并根据Merten方程,拟合出了斜声子的方向色散曲线;记录了A₁类电磁激元在不同波矢值下的喇曼谱,观察到其频率色散现象.根据以上结果,对A₁(TO)模喇曼谱中两个宽的非对称峰的归属和BaTiO₃晶体的结构相变机制进行了讨论;计算出了这两种晶体的受夹介电常数;分析了掺Ce对BaTiO₃晶体结构的影响。 关键词：     

光折变晶体Ce:BaTiO3电光和压电系数的测量

用干涉仪的方法测量了Ce:BaTiO₃晶体的低频电光系数和压电系数．排除压电效应对光通过晶体引起相位的变化，得到低频下经极化的Ce:BaTiO₃单晶的电光系数r₄₂=1945±220pm/V和r₁₃=11.8±1pm/V．从而，为研究Ce:BaTiO₃晶体的光折变效应和理论计算提供了精确的线性电光系数 关键词：     

四方相BaTiO_3:Ce及Mn离子注入的BaTiO_3:Ce的拉曼散射的研究

四方相ＢａＴｉＯ３：Ｃｅ及Ｍｎ离子注入的ＢａＴｉＯ３：Ｃｅ的拉曼散射的研究刘玉龙朱恪张昊朱镛（中科院物理研究所北京１０００８０）赵金涛（张掖师范高等专科学校物理系甘肃张掖７３４０００）萧季驹（香港城市大学物理及材料科学系香港九龙）ＲａｍａｎＳｐｅｃ...     

Sixth Harmonic of A Nd：YVO4 Laser Generation In KBBF for ARPES

We report that a deep ultraviolet （DUV） laser from the sixth harmonic of a 1064nm laser has been firstly used as light source in an ultrahigh energy-resolution angle-resolved photoemission spectroscopy （ARPES）. The wavelength is 177.3nm obtained by using the second harmonic KBe2BO3F2 crystal with a frequency tripled 1064nm Nd：YVO4 laser. The large flux （10^14 - 10^15 photons/s） and narrow line width （0.26 meV） are suitable for the ultrahigh-energy resolution ARPES. The laser-ARPES can be a powerful tool to study the electronic structure at and near the Fermi level of the superconductor and correlated materials. The laser-ARPES has worked more than 500 h already.     

BaTiO3和Ce:BaTiO3单晶的高温喇曼散射研究

从室温至180℃测量了BaTiO₃和Ce:BaTiO₃单晶的偏振喇曼谱,在X(ZZ)Y几何配置下发现了三条频率分别为986,1204和1480cm^-1的新谱线.根据喇曼散射截面的温度依赖关系,确认这些新谱线对应二阶喇曼散射,而A₁(TO)谱中位于275和514cm^-1处的非对称宽峰则属于一阶喇曼散射.在此基础上,对立方相BaTiO₃的喇曼谱和结构相变机制进行了讨论.通过比较B     

令人瞩目的光折变材料——钛酸钡晶体

 1988年12月6日,中国科学院物理所生长的钛酸钡（BaTiO₃）晶体通过院级鉴定（见封2照片）.不少美、日等国外有关部门已开始向物理所订货,目前,这种晶体在国际市场的价格是每克四千到五千美元,即购买一块与指甲差不多大小的晶体,约需化费四千美元.为什么如此昂贵的材料还这么抢手呢?其原因在于钛酸钡晶体是具有良好性能的非线性光学材料,无论从基础研究价值上还是应用前景上看,都有极为重要的意义.本文只就与这种材料的光折变性能有关的一些知识作一简介.