Raman scattering from a superconductivity-induced bound state in MgB2

It is shown that the sharp peak in the E(2g) Raman spectrum of superconducting MgB2 is due to a bound state caused by the electron-phonon coupling. Our theory explains why this peak appears only in the spectra with E(2g) symmetry and only in the sigma but not the pi bands. The properties of the bound state and the Raman spectrum are investigated, also in the presence of impurity scattering.     

马来酸氢十八酯晶体(OHM)的拉曼光谱研究

为了进一步了解马来酸氢十八酯晶体（ＯＨＭ）的结构,本文测定了ＯＨＭ晶体几何配置为（ｙ（ｚｘ）ｙ）和ｙ（ｘｚ）ｙ和ｙ（ｘｘ）的拉曼光谱。实验表明ＯＨＭ烷烃链的几个振动模式出现偏振,垛;ＯＨＭＳ其他基团的拉曼光谱振动吸收峰也都具应出现。     

琥珀酸氢十八酯晶体(OHS)的拉曼光谱研究

为了了解琥珀酸氢十八酯晶体（OHS）的结构,本文测定了OHS晶体几何配置为y^-(zx)y和y^-(zz)y和几何配置为y^-(xz)y和^y-(xx)y的拉曼光谱,实验表明：涉及到OHS烷烃链的几个振动模式都出现偏振动,由此可推测其晶体结构可能是以双聚体沿[100]和[001]方向排列成层,沿[010]方向堆垛,OHS其他基团的拉曼光谱振动吸收峰也都相应出现。     

Evidence for two superconducting gaps in MgB2

We have measured the Raman spectra of polycrystalline MgB2 from 25 to 1200 cm(-1). A superconductivity-induced redistribution in the electronic Raman continuum was observed. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. The measured spectra were analyzed using a quasi-two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained Delta(1) = 22 cm(-1) ( 2.7 meV) and Delta(2) = 50 cm(-1) ( 6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron sigma bands and is responsible for the superconductivity of MgB2.     

爆轰合成纳米超微金刚石的Raman光谱表征

 用炸药爆轰的方法制备了纳米超微金刚石,对纳米超微金刚石进行了激光Raman光谱分析。研究发现,在1 321 cm^-1和1 600 cm^-1附近观察到了对应于sp³金刚石和sp²石墨的特征峰,金刚石的Raman峰向低波数方向移动了约10 cm^-1,其半高宽约30 cm^-1,同时在低波数方向出现尾巴,呈现非对称的Raman波谱。Raman光谱分析的结果与X射线衍射分析的结果符合。     

用拉曼散射分析碲镉汞中的缺陷

本文分析了碲镉汞（HgCdTe或MCT）中Te沉淀相,Hg空位的拉曼散射峰,以及碲镉汞表面完整性与它的二级拉曼散射峰的关系,MCT中的Te沉淀相的拉曼峰位于125和145cm^-1处,此峰与标准的Te三角晶系的拉曼峰相比,往高能方向移动了2cm^-1,这表明Te沉淀相受到了压应力的作用,MCT中位于108cm^-1处微弱的拉曼峰来源于Hg空位,此峰只在p型和包含有反型层的MCT中出现,在n型的MCT中几乎不出现,MCT的拉曼二极散射峰对其表面完整性非常敏感,表面完整性好的拉曼峰很明显,而表面完整性较差的峰则不太明显,此峰的1LO（T）模的强度测量对晶体制备过程中的表面分析也可能供有用的信息。     

Si/SiGe异质结构的硅盖层中应变对Raman谱特征的影响

应变Si/SiGe异质结构通过大剂量Ge离子注入并结合高温快速热退火制备而成。325 nm波长的紫外激光被用于调查应变Si盖层的Raman谱特征。实验发现,硅盖层中的张应变导致硅的520 cm-1的一级拉曼散射峰向低频方向偏移,峰的偏移程度反映硅盖层中横向张应力的大小约为12.5×108 N·m-2。硅盖层中的张应变并未导致1 555和2 330 cm-1的次级拉曼散射峰的变化。     

Superconducting gap in MgB(2): electronic Raman scattering measurements of single crystals

Polarization-resolved Raman scattering measurements were performed on MgB(2) single crystals to determine the magnitude, symmetry, and temperature dependence of the superconducting gap. A single sharp peak due to Cooper pair breaking appears in the electronic continuum below T(c), reaching a maximum Raman shift of 105 +/- 1 cm(-1) [2 Delta(0)/k(B)T(c) = 3.96 +/- 0.09] and showing up to 5 cm(-1) anisotropy between polarized and depolarized spectra. The temperature dependence of 2 Delta follows that predicted from BCS theory, while the anisotropy decreases with decreasing temperature. It is concluded that the Raman results are consistent with a slightly anisotropic s-wave gap in a conventional BCS superconductor.     

Anomalous electronic Raman scattering in NaxCoO2.yH2O

Raman scattering experiments on NaxCoO2.yH2O single crystals show a broad electronic continuum with a pronounced peak around 100 cm(-1) and a cutoff at approximately 560 cm(-1) over a wide range of doping levels. The electronic Raman spectra in superconducting and nonsuperconducting samples are similar at room temperature, but evolve in markedly different ways with decreasing temperature. For superconducting samples, the low-energy spectral weight is depleted upon cooling below T* approximately 150 K, indicating the opening of a pseudogap that is not present in nonsuperconducting materials. Weak additional phonon modes observed below T* suggest that the pseudogap is associated with charge ordering.     

氯化钾对银胶中碱性品红表面增强拉曼散射的影响

测量了银胶中碱性品红的表面增强拉曼散射（ＳＥＲＳ）光谱。系统考察了不同波长光激发下ＫＣｌ对碱性品红ＳＥＲＳ光谱的影响，给出了不同波长光激发下碱怀品红的１３６６ｃｍ＾－１和２４２ｃｍ＾－１峰相对强度随ＫＣｌ量（或浓度对数值）的变化曲线，５１４．５ｎｍ和６３２．８ｎｍ光激发的碱性品红的ＳＥＲＳ谱有明显差异，２４２ｃｍ＾－１峰与其他峰的相对强度发生变化。     

反斯托克斯拉曼光谱在BaTiO_3铁电相变研究中的应用

从理论上讨论了一阶和二阶斯托克斯与反斯托克斯拉曼散射截面的温度依赖关系;在２９３Ｋ至４０１Ｋ的温度范围内,测量了ＢａＴｉＯ３单晶斯托克斯和反斯托克斯过程的偏振拉曼光谱;通过对ＢａＴｉＯ３单晶斯托克斯和反斯托克斯拉曼光谱的综合分析,证实在Ｘ（ＺＺ）Ｙ几何配置下测量到的位于２７５和５１４ｃｍ－１处的强峰为一阶拉曼光谱。此结果支持了ＢａＴｉＯ３铁电相变机制的有序—无序模型。     

Negative quantum interference between the electronic Raman scattering processes of CuO chains and CuO2 planes of heavily overdoped (Y, Ca)Ba2Cu3O(7-delta)

We found a strong X-Y anisotropy of the pair-breaking peak in the Raman scattering of heavily overdoped (Y, Ca)Ba2Cu3O(7-delta) (T(c) = 65 K). The pair-breaking peak is radically suppressed in the YY-polarized spectrum. We ascribe this anomaly to the effect of quantum interference between the Raman processes of the CuO-chain and the CuO2-plane electronic excitations that might take place as a result of the increase in the transfer matrix due to overdoping.     

Temperature Dependence for the Relative Raman Cross Section of the Ammonia/Water Complex

The Raman spectra of aqueous ammonia solutions have been obtained between -40 and 25 degrees C. The Raman spectrum of neat water was also obtained at 25 degrees C and is characterized by two broad peaks observed at 3200 and 3400 cm(-1). The spectrum due to water is subtracted to determine the NH(3) spectrum at all temperatures. In ammonia-water solutions, the spectrum shows three features at measured displacements of 3250, 3316, and 3400 cm(-1). The feature at 3316 cm(-1) is assigned to the Q branch of the symmetric stretch. The broad, weak features at 3250 and 3400 cm(-1), previously assigned to rotational bands, are assigned to combination bands. The NH(3) combination bands are assigned by comparing with sum frequency generation (SFG) experiments, monitoring changes with temperature, and analyzing the polarization data. The rotational structure of the Q band is also discussed. As the temperature is lowered from 25 to -40 degrees C, an increase in the Raman intensity is observed for all bands. The relative Raman scattering cross section is determined from the numerically integrated area of the NH(3) Q branch at each temperature. Copyright 2001 Academic Press.     

Overtone Raman Scattering in Lithium Tantalate Single Crystals

Optics and Spectroscopy - Overtone bands in the spectral range of 1300−1920 cm–1 have been found in Raman scattering spectrum of lithium tantalate single crystals. The Raman spectra...     

Transfer-of-coherence-enhanced stimulated emission and electromagnetically induced absorption in Zeeman split Fg-->Fe=Fg-1 atomic transitions

The probe absorption spectra in single and multiple tripod systems formed when a weak sigma polarized pump and a tunable pi polarized probe interact with a Zeeman split F(g)-->F(e)=F(g)-1 atomic transition are characterized by two interfering stimulated Raman features separated by an electromagnetically induced absorption (EIA) peak at the line center. These Raman features can appear as either sharp stimulated emission peaks or electromagnetically induced transparency windows. In the multitripod systems, the EIA and stimulated emission peaks derive from the combined effects of interference between the stimulated Raman features and transfer of coherence from the excited to ground states.     

美国通用电气公司宝石级合成翡翠的振动谱学研究

对近来面市的美国通用电气公司的宝石级合成翡翠,使用傅里叶红外光谱仪、 激光拉曼光谱仪等谱学分析测试仪器进行测试,研究其振动光谱,试图从振动谱学的角度分析研究这种合成翡翠的特征,并比较它与天然翡翠的异同。研究结果表明： 在红外光谱方面： 美国通用电气公司宝石级合成翡翠的指纹区与天然翡翠的基本相同; 而在基团频率区,则有明显的不同： 在3 400～3 700 cm-1范围内显示一组由OH的伸缩振动导致的特征吸收谱带: 3 375,3 471和3 614 cm-1。揭示了合成翡翠中含有一定数量的羟基。在拉曼光谱方面,一组376,700,989和1 039 cm-1的尖锐吸收峰一方面显示了和天然翡翠的拉曼特征一致性,另一方面也显示其具有完好的结晶形态,红外光谱和拉曼光谱均显示了样品中重质量的阳离子的缺乏。     

内吞金纳米粒子的鼻咽癌细胞SERS光谱

采用内吞方法将金纳米粒子引入细胞内,测试分析单个活性CNE-1鼻咽癌细胞的常规拉曼光谱和SERS光谱,并对其进行初步谱峰归属。CNE-1细胞的常规拉曼光谱有6个主要的拉曼峰:718,1001,1123,1336,1446和1660cm-1;沉积于细胞内的金纳米粒子强烈地增强了细胞内生化物质拉曼信号,在内吞金纳米粒子的CNE-1细胞的拉曼光谱中出现了20多个SERS拉曼信号,主要拉曼峰的强度明显高于常规拉曼信号。DNA骨架振动(1026,1097,1336和1585cm-1)证明金纳米粒子通过内吞作用而进入细胞核内。结果表明,基于胶体金SERS技术可能为活性鼻咽癌细胞内生化物质的探测提供一种高灵敏的方法。     

氨基酸在银胶溶液中的表面增强拉曼效应

文章报道了通过制备合适的银胶盐纳米溶液 ,得到的甘氨酸、缬氨酸和赖氨酸在银胶溶液中的表面增强拉曼光谱。低波数 2 38cm-1谱带的出现 ,表明氨基酸分子已与银表面产生明显吸附。在所得SERS图谱中 ,表征C—C基团的 90 0～ 930cm-1谱带、表征NH2 基团的 110 0cm-1左右谱带和表征COO-基团的14 0 0cm-1附近的谱带振动都得到显著加强 ,其原因主要是通过羧基基团及氨基基团与银粒子表面产生吸附 ,增强机制属于化学增强 ,为短程效应。本实验中 ,当银胶溶液 pH值降低时 ,对拉曼散射的增强效果影响不大。     

紫金山金铜矿明矾石的拉曼光谱特征

紫金山金铜矿是我国大陆首例高硫化型浅成低温热液型矿床。矿床上金下铜,金矿主要赋存在潜水面以上,与强硅化有关;铜矿主要赋存于潜水面之下,与明矾石化有关。明矾石有四种产出状态,分别为蚀变岩型、与铜硫化物共生型、后期脉状、粉末状。不同产出状态的明矾石具有不同的拉曼光谱特征和荧光散射背景。明矾石流体包裹体激光拉曼谱图显示：(1)从蚀变岩型、与铜硫矿化物共生型到后期脉状明矾石均具有明矾石特征性的谱带,只是受荧光散射影响逐渐减弱;粉末状明矾石具有与前三者不同的谱带特性,各谱带强度均较弱,荧光散射较强烈。(2)100～700 cm-1区间谱带可作为明矾石分子结构中阳离子类质同象置换的“指纹谱带”。蚀变岩型明矾石,161和234 cm-1峰变化明显,具有较广泛的Na对K的类质同象置换;与铜硫化物共生的明矾石,381和484 cm-1峰变化明显,指示Cu和Ga等阳离子对Al离子的类质同象置换;后期脉状明矾石,161, 234,484,508 cm-1峰值均比较稳定,Na对K和Si对Al的类质同象置换较少;潜水面附近的粉末状明矾石因荧光散射强烈,各个谱带强度均较弱。(3)明矾石的激光拉曼光谱和红外光谱配合使用,可为明矾石矿物研究提供完整的分子振动光谱特征,为明矾石的成因提供结构信息。在岩相学、矿相学、矿床地质、矿床地球化学、区域地质特征研究的基础上,通过明矾石的激光拉曼光谱(结合荧光散射背景)可进一步为紫金山金铜矿这个典型的高硫化型浅成低温热液矿床的形成机制提供演化进程信息。     

几种哌嗪类抗肿瘤化合物的拉曼光谱

几种哌嗪类抗肿瘤化合物的拉曼光谱刘社文１梁二军１李祥杰２（１郑州大学河南省激光应用技术重点实验室，２郑州大学化学化工学院，郑州４５００５２）ＲａｍａｎＳｐｅｃｔｒａｏｆＳｅｖｅｒａｌＡｎｔｉｔｕｍｏｒＰｉｐｅｒａｚｉｎｅｓＣｏｍｐｏｕｎｄｓＬｉｕＳｈ...