Ge-As-S硫系玻璃的结构与性能调控

制备了系列具有不同化学配比特征的Ge-As-S硫系玻璃,并研究了玻璃的结构、折射率和光学带隙(Eg).Ge-As-S玻璃具有以[Ge S_4]四面体和[As S_3]三角锥为骨架结构单元相互交联形成的连续网络结构,当S过量时,结构中出现S链或S_8环;当S不足时,结构中形成As_4S_4/As_4S_3分子,甚至出现大量AsAs/Ge-Ge同极键.玻璃的组成元素在2—10μm波段的摩尔折射度分别为R_(Ge)=9.83—10.42 cm~3/mol,RAs=11.72—11.87 cm~3/mol和R_S=7.78—7.86 cm3/mol.Ge-As-S玻璃的折射率与密度和组成元素的摩尔折射度之间存在较好的定量关系,可根据该定量关系在1%偏差内对玻璃的折射率进行预测或调控.提出了采用玻璃粉末的漫反射光谱确定可靠Eg的方法,通过该方法可获得玻璃的强吸收数据用于确定Eg.Ge-As-S玻璃的Eg与玻璃的平均键能之间存在较好的关联,S含量较高的玻璃更倾向于具有较大的平均键能,因此具有较大的Eg.     

Ultra-broadband modulation instability gain characteristics in As_2S_3 and As_2Se_3 chalcogenide glass photonic crystal fiber

Based on the designed As_2Se_3 and As_2S_3 chalcogenide glass photonic crystal fiber(PCF) and the scalar nonlinear Schrdinger equation,the effects of pump power and wavelength on modulation instability(MI) gain are comprehensively studied in the abnormal dispersion regime of chalcogenide glass PCF.Owing to high Raman effect and high nonlinearity,ultra-broadband MI gain is obtained in chalcogenide glass PCF.By choosing the appropriate pump parameter,the MI gain bandwidth reaches 2738 nm for the As_2Se_3 glass PCF in the abnormal-dispersion region,while it is 1961 nm for the As_2S_3 glass PCF.     

Photoinduced dichroism in lightsensitive suspension layers of As2S3 dispersed in gelatin

The absorption edge shift and the spectra of the dichroism in suspension layers of As₂S₃ dispersed in gelatin induced by a linearly polarized laser light are measured. The results are compared to the photoinduced changes in evaporated As₂S₃ layers.     

Linear optical characterization of chalcogenide glasses

A simple experimental method is used to obtain the evolution of both the refractive index and the linear absorption coefficient as a function of the optical wavelength in the near infrared range (from 900 up to 1700 nm with 10 nm resolution). Several chalcogenide glasses (As₂S₃, As₂Se₃, GeSe₄) are tested and the corresponding Cauchy coefficients are determined. Comparison of our results shows a good agreement with values available in the literature at some wavelength. Application of this method is used to estimate Cauchy coefficients of Ge₁₀As₁₀Se₈₀ for the first time to our best knowledge.     

Numerical investigation on broadband mid-infrared supercontinuum generation in chalcogenide suspended-core fibers

As_2S_3 and As_2Se_3 chalcogenide 3-bridges suspended-core fibers(SCFs) are designed with shifted zero-dispersion wavelengths(ZDWs) at around 1.5 μm, 2 μm, and 2.8 μm, respectively. A generalized nonlinear Schr ¨odinger equation is used to numerically compare supercontinuum(SC) generation in these SCFs pumped at an anomalous dispersion region nearby their ZDWs. Evolutions of the long-wavelength edge(LWE), the power proportion in the long-wavelength region(PPL), and spectral flatness(SF) are calculated and analyzed. Meanwhile, the optimal pump parameters and fiber length are given with LWE, PPL, and SF taken into account. For As_2S_3 SCFs, SC from a 14 mm-long fiber with a ZDW of 2825 nm pumped at 2870 nm can achieve the longest LWE of ～ 13 μm and PPL up to ～72%. For As_2Se_3 SCFs, the LWE of 15.5 μm and the highest PPL of ～ 87% can be achieved in a 10 mm-long fiber with ZDW of 1982 nm pumped at 2000 nm. Although the As_2Se_3 SCFs can achieve much longer LWE than the As_2S_3 SCFs, the core diameter of As_2Se_3 SCFs will be much smaller to obtain a similar ZDW, leading to lower damage threshold and output power. Finally, the optimal parameters for generating SC spanning over different mid-IR windows are given.     

Photoelastic properties of amorphous As2S3

The piezobirefringence of amorphous As₂S₃ was measured in the wavelength range 0.69 to 1.15 μ, and the pressure dependence of the index of refraction was determined at 0.633 and 1.15μ. The dispersion of the photoelastic constants of As₂S₃ is discussed using a one-oscillator model, and compared with the results of a similar analysis performed on GaAs.     

用高压显微光谱系统测量流体静压力对非晶态As2S3光学吸收边的影响

用金刚石对顶砧高压显微光谱系统在0—66kbar的流体静压力范围内测量了a-As₂S₃的光学吸收达随压力的移动特性。发现a-As₂S₃的光学吸收边随压力的增加而迅速红移。在计算机上用最小二乘法对实验点进行了拟合,结果得出吸收边和压力之间的关系为:E_g(P)=E_g(0)-1.31×10^-3P-3.91×10^-4P²+4.04×10^-6P³值得注意的是|dE_g/dP|和压力之间的关系经历了一个先是增大,然后再减小以至于趋于饱和的过程。这和Weinstein等人先前的实验结果是有所不同的。 关键词：     

Lattice Dynamics at Zone-Center of Sulphide and Selenide Spinels

A rigid-ion model is used to calculate the force constants and effective dynamical charges of sulphide and selenide spinels. The Raman and infrared phonon modes of normal cubic sulphide spinels MCr₂Se₄ (M = Mn, Co, Fe, Hg, Zn, and Cd) and selenide spinels MCr₂Se₄ (M = Hg, Zn, and Cd) are calculated at the first Brillouin zone-centre using above model. The significant outcome of the present work is (i) the interatomic interaction between Cr-S (Se) dominates over the Cr-S(Se) and S-S(Se-Se) type of interatomic interactions, (ii) the effective dynamical charges of the bivalent metal ions are nearly zero, and (iii) the selenide spinels are less ionic than the sulphide spinels and the ionicity decreases as MnCr₂S₄ > FeCr₂S₄ > CoCr₂S₄ > and CdCr₂C₄ > ZnCr₂C₄ > HgCr₂C₄ (C = S and Se). The zone-center phonon frequencies, calculated using these parameters, are found to be in very good agreement with the observed results.     

Structural evolution study of additions of Sb_2S_3 and CdS into GeS_2 chalcogenide glass by Raman spectroscopy

The structures of pseudo-binary GeS_2–Sb_2S_3, GeS_2–CdS, Sb_2S_3–CdS, and pseudo-ternary GeS_2–Sb_2S_3–CdS chalcogenide systems are systematically investigated by Raman spectroscopy. It is shown that a small number of [S_3Ge–GeS_3]structural units(SUs) and-S-S-/S8 groups exist simultaneously in GeS_2 glass which has a three-dimensional continuous network backbone consisting of cross-linked corner-sharing and edge-sharing [GeS_4] tetrahedra. When Sb_2S_3 is added into GeS_2 glass, the network backbone becomes interconnected [GeS_4] tetrahedra and [SbS_3] pyramids. Moreover, Ge atoms in[S_3Ge–GeS_3] SUs tend to capture S atoms from Sb_2S_3, leading to the formation of [S_2Sb–SbS_2] SUs. When CdS is added into GeS_2 glass, [Cd_4GeS_6] polyhedra are formed, resulting in a strong crystallization tendency. In addition, Ge atoms in[S_3Ge–GeS_3] SUs tend to capture S atoms from CdS, resulting in the dissolution of Ge–Ge bond. Co-melting of Sb_2S_3 or CdS with GeS_2 reduces the viscosity of the melt and improves the homogeneity of the glass. The GeS_2 glass can only dissolve up to 10-mol% CdS without crystallization. In comparison, GeS_2–Sb_2S_3 glasses can dissolve up to 20-mol% CdS,implying that Sb_2S_3 could delay the construction of [Cd_4GeS_6] polyhedron and increase the dissolving amount of CdS in the glass.     

Terahertz magnetic resonance in MnCr2O4 under high magnetic field

Terahertz (THz) time-domain spectroscopy (THz-TDS) of polycrystalline MnCr₂O₄ was performed at <9 T and low temperatures. A resonance absorption in the sub-THz range with linear blueshifts was observed as the magnetic field was increased from 4 T to 9 T. These magnetism-driven absorptions originated from a ferromagnetic resonance, which agrees with low-field electron spin resonance measurements and ferromagnetic resonance theory. The low-temperature g-factors of MnCr₂O₄ were also obtained using THz-TDS. This work provides new insights into the spin dynamics of chromite spinel compounds in the THz region.     

Tm~(3+)掺杂Ge-Ga-S玻璃微球-石英光纤锥耦合系统的荧光回廊模特性

以熔融淬冷法自制了Tm~(3+)掺杂Ge-Ga-S硫系玻璃,并以此为基质材料,用漂浮粉料熔融法制备了直径分布为50—200μm的高品质因数(Q10~4)的有源硫系玻璃微球谐振腔.在显微镜下优选出一颗表面质量好、球形度较高、直径为72.84μm的微球,与氢氧焰扫描拉锥法制备的一根腰锥直径为1.93μm的石英光纤锥进行近场耦合.根据基质材料的吸收光谱特性,选用808 nm的半导体激光器作为抽运源.实验测得光纤锥倏逝波场激发出了掺Tm~(3+)硫系玻璃微球在1460 nm附近的荧光回廊模式,其典型共振峰间隔为4.39 nm.实验测得的荧光回廊模式与米氏散射理论计算结果符合度较高(最大误差仅为0.047%),验证了本文提出的掺Tm~(3+)硫系微球制备及耦合工艺的可行性.     

1,4-萘醌的太赫兹,远红外及低频拉曼光谱研究

本文对1,4-萘醌进行了太赫兹时域光谱,远红外吸收光谱及低频拉曼散射谱的测试研究。1,4-萘醌的太赫兹吸收光谱与远红外谱仪测得的光谱取得了在1.75 THz(58.3 cm-1)/1.63 THz(54.3 cm-1)等处吸收峰位基本相同、两者相互佐证和补充的结果。将太赫兹和远红外吸收谱与低频拉曼散射谱进行比较,表明两种选择机制不同的光谱在1.04,1.72和4.59 THz等处的峰位基本重合,结合群论的不可约表示理论分析,表明该样品在低频波段具有拉曼活性和红外活性的振动属性(A1、B1或B2)。采用Gaussi-an03软件的密度泛函理论B3LYP函数和6-311基组模拟单分子红外与拉曼光谱,结合实验分析,对部分分子基团或原子振转模式给与了指认。     

苏氨酸的太赫兹及拉曼光谱研究

采用太赫兹时域光谱和拉曼光谱法对L-苏氨酸多晶粉末进行测试研究,获得了样品在0.2—2.8 THz（6.7—93.2 cm^-1）波段的特征吸收和10—4000 cm^－1波段的拉曼散射谱;分别在6.7—93.2 cm^－1和400—4000 cm^－1两个波段进行了吸收光谱与拉曼散射光谱的对比,根据晶胞分子所属的空间群,对隶属于分子的极性和非极性振动模式（A, B₁, 关键词： 太赫兹光谱 拉曼散射 氨基酸     

温度对低共熔溶剂影响的二维拉曼光谱研究

低共熔溶剂（DES）作为一种新式的绿色溶剂，在多种化学过程中表现出色，因此在诸多热门范畴都展现出良好的发展潜力。对DES的光谱分析通常局限在一维光谱技术上，但其分辨率低、谱峰重叠严重等缺点，导致光谱数据存在误差。运用二维拉曼光谱（2D Raman），能够明显提高光谱分辨率，并发现重叠峰位置，获得在外扰条件下不同谱峰的变化顺序及其相互作用等重要信息，以实现对复杂体系的精确分析。以氯化胆碱（ChCl）和ZnCl₂合成的DES为例，利用显微共焦激光拉曼光谱仪分别对ChCl和DES进行拉曼实验，发现与ChCl相比，DES中各处峰的整体强度显著下降，原有的谱峰未消失，说明Zn2+的加入没有破坏ChCl的骨架结构。287 cm-1处出现一个新的特征峰，推测有Zn-Cl配位键的伸缩振动。对DES进行升温拉曼实验，发现随着温度的升高，NC₄的不对称伸缩振动峰强度逐渐减小，峰宽变大，峰形变缓，Zn-Cl配位键伸缩振动峰强度逐渐降低，峰位置基本不变，峰形有明显重叠。运用2D Raman技术对溶液内NC₄和Zn-Cl特征峰的变化进行研究，结果表明，随着温度的升高，溶液中发生ChCl向Ch+的解离过程，Zn2+与Cl-形成了多种配合物，ZnCl-₃，Zn₂Cl-₅，Zn₃Cl-₇之间存在相互转化。不同位置的特征峰随温度的变化顺序不同，将特征峰与团簇进行一一归属，得出了各个团簇对温度的敏感程度。基于量子化学中的密度泛函理论，对推测的物质结构进行构型优化和参数计算，证实了其存在的可能性，同时也验证了2D Raman的分析结果准确可行。这些结果将为DES的后续研究提供理论参考，拓展了二维光谱技术的应用范围。     

高温高压处理对褐色CVD钻石谱学特征的影响

目前CVD法合成单晶钻石是超硬材料科学和宝石学关注的热点之一,该方法合成的单晶钻石常带有褐色调。通常采用高温高压法（HPHT）提高褐色CVD钻石的色级和透明度,在前期HPHT处理褐色CVD钻石实验基础上,选出颜色改善明显的三颗样品,对其处理前后谱学特征进行对比。采用紫外-可见吸收光谱、红外光谱、光致发光光谱、三维荧光光谱、激光拉曼光谱以及X射线摇摆曲线进行分析。结果表明,褐色和深褐色样品褪色温度较高,处理后样品紫外-可见吸收光谱吸收系数明显减小,透明度明显提高。样品中红外与近红外光谱显示,在1 332 cm-1处的吸收峰与N+中心有关,该中心是褐色CVD钻石常见特征。在3 124 cm-1处吸收峰与NVH0缺陷中心有关,该峰在CVD钻石和HPHT处理钻石中常见。另外在2 700~3 200 cm-1范围变化的一组吸收峰,与C-H键伸缩振动有关。高温对CVD钻石含H基团影响较大,在5~6 GPa压力下处理温度在1 500~1 700 ℃范围,会在近红外波段4 673,6 352,7 354,7 540,7 804和8 535 cm-1出现一组吸收峰,可指示样品经过较高温度处理。目前针对CVD钻石以及经过HPHT处理的CVD钻石近红外波段的论述较少,该研究可以为鉴定CVD钻石及HPHT处理CVD钻石提供依据。综合光致发光光谱和三维荧光光谱分析,处理后样品NV-缺陷比例减小,SiV-中心缺陷比例增加。在5~6 GPa压力下,仅当处理温度高于1 500 ℃时,样品三维荧光光谱在λ_ex/λ_em=500 nm/575 nm处荧光峰增强,在λ_ex/λ_em=490 nm/550 nm处荧光峰消失,从某种意义上该峰位变化可指示样品经过较高温度处理。物相分析结果显示,HPHT处理后CVD钻石在1 332 cm-1处拉曼位移半高宽和XRD摇摆曲线半高宽均减小,表现出了较好的一致性,说明经HPHT处理的褐色CVD钻石结晶质量变优。     

邛崃石窟摩崖造像的彩绘颜料分析与研究

四川省邛崃市地处成都平原,是成都地区发现的摩崖造像规模最大,分布最集中的地区。由于潮湿、半露天的保存环境,造像遭到严重破坏,缺少相关的科学分析研究。本文选用邛崃地区内花置寺摩崖造像、临邛镇磐陀寺摩崖造像和大同乡石笋山摩崖造像三处共12件彩绘颜料样品,通过超景深显微观察、X射线荧光分析、X射线衍射和显微激光拉曼光谱综合分析,获取彩绘颜料信息。结果表明红色颜料为赤铁矿[Fe₂O₃]和铅丹[Pb₃O₄];绿色颜料为砷酸铜[Cu(AsO₃)(OH)·2H₂O]和过硫酸三铜钠钾[KNaCu₃O(SO₄)₃];白色颜料为石膏[CaSO₄];黄色颜料为黄赭石[Fe₂O₃];黑色颜料为铅丹[Pb₃O₄]的变化产物,蓝色颜料为青金石[Na₆Ca₂Al₆Si₆O₂₄(SO₄)₂]。值得注意的是绿色颜料的分析结果,其中检出的砷酸铜类物质在近年中国西南地区彩绘分析中较常见,结合文献调研判断其为近现代人工合成颜料巴黎绿的变化产物,进而推测此处有近现代重绘可能。另外,首次检出过硫酸三铜钠钾成分的绿色颜料,丰富了古代彩绘颜料的分析实例,判断可能是某种绿色含铜矿物的变化结果。四川地区环境湿润,一些不稳定的矿物颜料容易发生化学变化,有的产生变色,有的颜色变化不明显,但成分已产生新的物质。通过分析邛崃石窟彩绘颜料,获取四川地区摩崖造像所使用颜料的相关信息,为颜料复原提供科学依据,同时也有利于文物工作者展开针对性保护工作,为四川地区彩绘石窟的研究和保护提供参考。     

拉曼光谱对含Cr镁铝尖晶石热处理及其有序-无序相变研究

尖晶石的有序-无序相变作为尖晶石的一种重要性质，在国内缺少相关研究成果。运用拉曼光谱仪通过785 nm激光在液氮环境下激发含Cr的宝石级天然粉红色尖晶石，避免了532 nm激光激发下产生的469 nm的荧光峰和在常温测试下由于热振动对光谱的影响，得到清晰尖锐的拉曼光谱，为拉曼光谱参数的分析奠定基础。同时通过对一颗Cr元素致色的天然粉色镁铝尖晶石进行热处理使尖晶石逐步发生有序-无序相变，并反映在拉曼光谱的谱峰参数之中。各项参数分析结果显示，尖晶石的拉曼光谱主要由E_g，T_2g(1)，T_2g(2)，N₃和A_g，五种振动模式产生，其谱峰位置分别为407.8，312.4，667.5，720.0和769.0 cm-1；尖晶石拉曼光谱谱峰参数在800 ℃时发生突变： 各谱峰半高宽和各峰相对主峰E_g峰的相对强度明显增大，常温下几乎不可见的N₃峰在高温处理后出现，并且T_2g(1)峰向低波数偏移，T_2g(2)向高波数偏移，同时峰的对称性逐渐消失。研究结果表明尖晶石的有序-无序相变可以通过拉曼光谱检测并且可以通过谱峰参数： 半高宽、谱峰相对高度等进行半定量表征。由于拉曼光谱具有的无损检测特点，使其成为宝石级热处理尖晶石鉴定应用的重要参考依据之一。     

Vibrational modes in ZnAl2S4 and CdIn2S4 crystals

Infrared reflectivity spectra and Raman scattering of the ZnAl₂S₄ and CdIn₂S₄ crystals have been investigated. Reflectivity spectra contours were calculated and phonon parameters and dielectric constants were determined. Effective charges for the Zn, Cd, In and S ions of these materials were determined.     

K,Na掺杂Cu-S纳米晶的水热合成及对结构、性能的影响

利用水热合成技术, 分别以CuCl₂·2H₂O, 硫粉为铜源和硫源, 以KOH或NaOH为矿化剂, 成功合成了Cu₂S纳米晶体和碱金属离子掺杂的KCu₇S₄纳米线和NaCu₅S₃ 微纳米球. 通过X射线衍射(XRD)、电子能谱(EDS)、扫描电镜(SEM)、透射电镜(TEM)和高分辨率透射电镜 (HRTEM) 对产物的结构和形貌进行了表征和分析. 结果显示: KOH含量低于1g或NaOH低于2g时, 产物为斜方辉铜矿Cu₂S; 高碱含量 (不低于3g) 时, K或Na离子成功掺入产物结构中, K掺杂产物为纯净的四方相KCu₇S₄, 单晶结构, 尺寸均匀, 长度可达几十微米的纳米线; Na掺杂未改变产物的形貌, 形成六方晶系结构的NaCu₅S₃. 产物的形成和生长与反应温度、反应时间和矿化剂密切相关. 并讨论了Cu₂S纳米晶及其掺杂纳米晶的形成机理及掺杂机理. 最后研究了碱金属离子掺杂对产物的光学性能的影响, 漫反射光谱显示Cu₂S, KCu₇S₄和NaCu₅S₃纳米晶的光学带隙分别为1.21eV, 0.49eV和0.42eV, K⁺和Na⁺的掺杂, 极大的改变了产物的光学特性. 关键词： 7S₄')" href="#">KCu₇S₄ 5S₃')" href="#">NaCu₅S₃ 水热法 掺杂     

Low-frequency vibrational modes of glutamine

High-resolution terahertz absorption and Raman spectra of glutamine in the frequency region 0.2 THz-2.8 THz are obtained by using THz time domain spectroscopy and low-frequency Raman spectroscopy. Based on the experimental and the computational results, the vibration modes corresponding to the terahertz absorption and Raman scatting peaks are assigned and further verified by the theoretical calculations. Spectral investigation of the periodic structure of glutamine based on the sophisticated hybrid density functional B3LYP indicates that the vibrational modes come mainly from the inter-molecular hydrogen bond in this frequency region.