Effect of heat-treatment on the surface properties of gallium phosphide nanosolids by Raman spectroscopy

Raman spectra of gallium phosphide （GAP） nanosolids （unheated and heat-treated at 598 and 723 K, respectively） were investigated. It was observed that both the longitudinal optical mode （LO） and the transverse optical mode （TO） displayed an asymmetry on the low-wavenumber side. The scattering bands were fitted to a sum of four Lorentzians which were assigned to the LO mode, surface phonon mode, TO mode, and a combination of Ga-O-P symmetric bending and sum band formed from the X-point TA ＋ LA phonons, respectively. Analysis of the characteristic of surface phonon mode revealed that the surface phonon peak of the GaP nanosolids could be confirmed. In the infrared spectrum of the GaP nanoparticles, we observed the bands on account of symmetric stretching and bending of PO2, as well as stretching of Ga-O The Raman scattering intensity arising from the Ga-O-P linkages increased as increasing the heat-treatment temperature.     

IR and Raman spectra of poled and unpoled LiNbO3 single crystals

LiNbO₃ single crystals were grown by the Czochralski technique in an air atmosphere. The polarized IR and Raman spectra of both poled and unpoled LiNbO₃ single crystals were measured and compared. The spectra were recorded at different temperatures between 20 and 300 K. In addition, we discussed the phonon anomalies and anharmonicity in both, IR and Raman spectra.     

Syntheses, characteristics and fluorescence properties of complexes of terbium with benzoic acid and its derivatives

The binary complexes of terbium with benzoic acid and its derivatives (phthalic acid, iso-phthalic acid, oaminobenzoic acid, salicylic acid, sulfosalicylic acid) were synthesized and their compositions were identified by elemental analyses. UV, IR of the complexes were investigated. The UV spectra indicate that the complexes‘ ultraviolet absorption is mainly the ligands‘ absorption, but the location of peak drifts. The IR spectra show that the IR spectra of complexes are different from those of free ligands, and the band at 400 - 500 cm^-1 , due to the stretching vibration of Tb--O, is absent for free ligands. The fluorescence properties were investigated by using luminescence spectroscope, the results show that all the six complexes of terbium exhibit excellent luminescence, due to the transition from the lowest excited state ^5D4 to ^7F ground state manifold, the complexes of terbium with sulfosalicylic acid have the strongest fluorescence intensity, and is stronger than o-aminobenzoic acid-terbium, whose fluorescence intensity is regarded as the strongest one in the literature, and even stronger than some phosphor of terbium.     

Crystal microstructure, infrared absorption, and microwave electromagnetic properties of （La1-xDyx）2/3Sr1/3MnO3

The manganite perovskite polycrystal samples of (La_1−x Dy _x )_2/3Sr_1/3MnO₃ (x = 0, 0.1, 0.2, 0.35, and 0.5) doped with Dy were prepared by solid state reaction in atmosphere to measure their X-ray diffraction (XRD) patterns, scanning electric microscope (SEM) images, infrared absorption spectra, and microwave electromagnetic properties. The displacement of the XRD peaks of the samples was found, and the 2ϑ increases from 0.05° to 0.5°. The grains of undoped La_2/3Sr_1/3MnO₃ not only have the greatest size, but also the most regular shape. The size of the grains decreases as the Dy doping content increases from 0 to 0.5. The infrared absorption spectra of all samples were measured at room temperature. An absorption peak corresponding to the stretching vibration mode of Mn-O bonds appears within the range of 591–629 cm⁻¹. The absorption peak shifts from a higher frequency to a lower one with the decrease of the average ionic radius of A-site. The frequency dependence of microwave-absorbing properties, imaginary components of the complex magnetic permeability μ″ and dielectric permeability ε″ for all samples was measured at room temperature from 8 to 13 GHz. The results show that the loss of microwave absorption can be attributed to both the magnetic and electric losses. The increase of Dy content not only enhances the microwave absorption but also causes the displacement of the absorption peaks.     

电化学沉积Nd掺杂ZnO薄膜的结构和光学性质的研究

用电化学沉积方法制备出了Nd掺杂的ZnO薄膜,并研究其结构和光学性质。X-射线衍射谱的结果表明Nd3 替代Zn2 进入到ZnO晶格中,并没有引起杂相的出现。吸收谱的分析表明,随着掺杂浓度的增大,吸收峰向短波长方向移动 ,即发生蓝移。光致发光谱的结果表明随着Nd3 掺杂浓度的增大,紫外峰强度减小,可见光部分强度增大了。     

Spectroelectrochemical study on the charging reactions of electrochemically synthesized films from 2-methoxynaphthalene

The charging–discharging reactions (both p- and n-doping) of films made electrochemically synthesized from 2-methoxynaphthalene in two different organic solvents have been studied by in situ Fourier Transform infrared (FTIR) spectroscopy using the attenuated total reflection, ATR, technique and by Raman spectroscopy. Films were made by cyclic voltammetry, CV. These films could be reversible both p- and n-doped. In situ FTIR–ATR measurements were made during charging–discharging of the electrosynthesized film in monomer-free 0.1 M TBAPF₆ solution. The IR spectra of the doped conducting state show infrared active vibrations (IRAV) bands in the region between 1300 and 700 cm⁻¹. The intensity of these bands increase with increasing charging level. In addition to these bands, a broad absorption can be seen in the high wavenumber region (4000–8000 cm⁻¹). The increased absorption is related to the movement of charged carriers in the film upon doping. FTIR data confirms that an electrically conducting conjugated structure with different redox properties and conjugation length was formed after synthesis in the two different electrolytes.     

Infrared studies of the phase transition in the organic charge transfer salt (ET)2C(CN)3

Polarized reflectance spectra from single crystals and powder absorption spectra of (ET)₂C(CN)₃ salt are measured in the middle IR region. The metal-insulator phase transition influences the IR spectra especially within the range of C = C vibrations. The strong coupling of electrons with ν₂₇(b_lu) mode (antisymmetric stretching of C = C ring bonds) is observed.     

Effect of alkyl position of pyrrole on structures and properties of conjugated polysquaraines

Poly(1-octylpyrrolyl)squaraine and poly(3-octylpyrrolyl)squaraine were synthesized from squaric acid with 1-octylpyrrole and 3-octylpyrrole under identical conditions of condensation. Visible absorption spectra, photoluminescence spectra, TGA curves, and IR spectra were recorded to characterize the structures of these polymers as synthesized; the measured optical and thermal properties are consistent with backbone structures. The polysquaraine from 3-octylpyrrole possesses mostly zwitterionic repeating units (>97%), but the polymer from 1-octylpyrrole consists of zwitterionic and covalent repeating units in a ratio 2:1. Observations from the visible absorption and photoluminescence spectra in varied solvents, TGA curves, and thermal IR measurements for these two polymers reconciled to their structures. This result indicates that the position of the alkyl group in the pyrrole derivative affects the conformation in the condensation of poly(pyrrolyl)squaraine. These polysquaraines are stable below temperature 155 °C and their visible absorption and photoluminescence properties in hydrogen-bonding solvents exhibit negative solvatochromism.     

First-Principles Investigation on Electronic Structure and Optical Properties of Wurtzite InxGa1-xN Alloys

采用密度泛函理论框架下的第一性原理平面波超软赝势方法,研究In掺杂对纤锌矿InxGa1-xN合金的晶格常数、能带结构、态密度和光学性质的影响。计算结果表明：随着In掺杂浓度的增加,晶格常数逐渐增大,导带向低能方向移动,带隙变窄;与此同时,介电函数向低能方向发生了漂移,发生了红移现象。在2.0 eV附近出现了第一个介电峰,在4.76 eV附近出现了最大的介电峰。在大约5.6 eV和9.2 eV处有两个交叉点,当光子能量低于5.6或者高于9.2 eV,低掺杂浓度(小于50%)的吸收系数小于高掺杂浓度的吸收系数;当光子能量在5.6到9.2 eV之间,低掺杂浓度的吸收系数高于高掺杂浓度的吸收系数。研究结果表明InxGa1-xN合金可以作为太阳能电池以及透明导电薄膜的材料     

Fourier transform infrared study of electrochemically prepared polythienylene films with varying doping levels

Fourier transform infrared (FTIR) spectra of electrochemically prepared polythienylene films doped with various dopant species at varying doping levels have been obtained. These doped polythienylene films exhibit four conspicuous absorption bands at 1330 - 1310, 1200, 1220 - 1080 and 1030 - 1020 cm^?1 made IR active and/or given prominent intensity due to the doping, independent of the difference in dopant species and contents. On the other hand, the bands specific to each dopant species are distinctly observable for the heavily-doped polythienylene films. Some typical band profiles in accordance with varied doping levels will be presented.     

Structure and optical characterization of GaP-SiO2 co-sputtered films

The films of GaP nanocrystals embedded in SiO2 matrix were prepared by radio frequency magnetron co-sputtering and subsequent anneal- ing technology. The structure and morphology of the films were investigated by scanning electron microscope, X-ray diffraction, and energy dispersive spectrum. Raman spectra results showed that the transverse optical phonon model (TO) and the longitudinal optical phonon model (LO) of GaP nanocrystals were both discovered to undergo red shift, broadening, and asymmetry. The red shift degree of the TO model was about 8.8 cm-1. The luminescence spectrum of the GaP/SiO2 film consisted of several emission peaks. 2.84-2.54 eV blue light emission was explained by the quantum confinement-luminescence centers model (QC-LCs).     

Growth interface of In-doped CdMnTe from Te solution with vertical Bridgman method under ACRT technique

CdMnTe (CMT) crystals were grown from Te solution with vertical Bridgman method under accelerated crucible rotation (ACRT) technique. Ingot in diameter of 30 mm and length of 60 mm was obtained. The result shows that as-grown CMT has fewer twins compared with the one grown by conventional vertical Bridgman method. However, IR microscopy shows that the microscopic growth interface morphology is non-uniform and irregular, which is attributed to higher Te inclusions density. Meanwhile, the laser confocal microscope images reveal that the Te phases are deposited randomly in the Te-rich CMT region with irregular shapes and voids. By optimizing the growth parameters to obtain a smooth interface, the Te solution vertical Bridgman technique can effectively reduce the twins in CMT crystal.     

ACRT-Te溶液Bridgman法生长的In掺杂CdMnTe界面研究(英文)

采用ACRT-Te溶液垂直布里奇曼法成功制备出直径为30mm、长度为60mm的CdMnTe晶锭。相对于普通布里奇曼法生长的CdMnTe晶锭,Te溶液法生长的 CdMnTe晶锭中的孪晶大大减少。但是由于较高的Te夹杂相密度,红外透过成像显示晶锭生长界面的微观形貌既不均匀也不规则。同时,采用激光共聚焦显微镜也观察到CdMnTe富Te区存在无规律沉积的含有孔洞的不规则形状Te相。如果采用合适的生长工艺得到较为平直的生长界面,Te溶液垂直布里奇曼法可以有效减少CdMnTe晶体中的孪晶。     

氮化碳薄膜的电子结构和光学性质

在不同条件下用射频溅射方法制备了氮化碳薄膜。薄膜的电子结构和元素成分用傅里叶变换红外光谱(FTIR)和光电子能谱 (XPS)进行分析 ,薄膜的光学性质用紫外可见近红外光谱 (UV)进行检测。薄膜中的最大氮原子含量达到 0 .4 7,C1s和N1s电子的结合能产生了 2 .4 1～ - 1.7eV的移动 ,移动的大小取决于制备条件。UV谱表明氮化碳薄膜能强烈地吸收紫外光 ,而对红外光有较好的透明性 ,在 2 72 0nm附近存在一明锐的吸收峰 ,并给出了形成这一明锐吸收峰的适宜条件。这些结果对作为保护光学涂层的红外应用是有意义的。     

Spectra of sodium aluminate solutions

The UV spectra of sodium aluminate solutions were obtained in the sodium oxide concentration range from 59 to 409 g/L and the caustic ratio range from 1.5 to 4.0 to reveal the structure characteristics of them. It is found that a new peak appears at about 370 nm besides peaks at about 220 and 266 nm in all solutions. The new peak is strongly favored by high hydroxide concentration and high caustic ratio. And it only appears when the solutions are prepared by dissolving sodium hydroxide and aluminum hydroxide. In addition, the IR and Raman spectra of sodium aluminate solutions with high alkali concentration and high caustic ratio were measured, and the UV spectra of aqueous solutions of Al（H2O）6^3＋ and AlF6^3- were measured as well. According to the crystal field theory in coordination chemistry as well as the above spectra characteristics, this new peak at about 370 nm is determined as the evidence of a new species of aluminate ion with a coordination number of 6.     

高剂量离子辐照效应对CdZnTe:In晶体光电性能的影响

研究了离子辐照效应对CdZnTe（CZT）晶体光电性能的影响。采用Ar离子对改进的垂直布里奇曼法生长的CZT晶体进行辐照，剂量范围为10¹⁴~10¹⁵ cm^-2。红外透过光谱测试结果表明，辐照前晶体样品的高直型光谱转变为辐照后的上升性光谱。辐照诱导产生的高浓度自由载流子引起的光吸收在红外透过光谱的中红外范围内占主导地位。由于离子辐照发生在单侧照射面的近表面区域，辐照后晶体样品的I-V特性曲线变得极不对称。在负偏压的条件下，电流随着电压的增大而急剧增大。霍尔效应测试结果表明，辐照前晶体样品的净载流子浓度约为10⁶ cm^-3，而辐照后的净载流子浓度大幅增加，约为10¹⁶ cm^-3。CZT晶体的导电类型在离子辐照前后并没有发生变化，施主缺陷能级在辐照诱导缺陷中占主导地位。     

Micro-Raman Spectroscopy for Stress Evaluation of 3C-SiC Epitaxially Grown on Si Substrate by Hot Wall CVD

GROWTH of large area3C-SiC films on Si hasattracted great interest since the early report onhetero-epitaxial growth by means of chemical vapordeposition(CVD)[1],due to its outstanding thermal,chemical and electrical properties for deviceapplications,such as,wide-band gap(2.3eV),highthermal conductivity(4.9W/cmK),high electronmobility(lOOOcmVVs)and high electron saturationdrift velocity(2.7xl07cm/s)[l,2].To our knowledge,the reports on the growth of SiC involved largely on the(100)Si,wi…     

Structure and optical characterization of GaP-SiO2 co-sputtered films

The films of GaP nanocrystals embedded in SiO₂ matrix were prepared by radio frequency magnetron co-sputtering and subsequent annealing technology. The structure and morphology of the films were investigated by scanning electron microscope, X-ray diffraction, and energy dispersive spectrum. Raman spectra results showed that the transverse optical phonon model (TO) and the longitudinal optical phonon model (LO) of GaP nanocrystals were both discovered to undergo red shift, broadening, and asymmetry. The red shift degree of the TO model was about 8.8 cm⁻¹. The luminescence spectrum of the GaP/SiO₂ film consisted of several emission peaks. 2.84–2.54 eV blue light emission was explained by the quantum confinement-luminescence centers model (QC-LCs).     

Structure and Raman scattering of Mg-doped ZnO nanoparticles prepared by sol-gel method

Mg-doped ZnO (Mg_xZn_(1-x)O, x=0-0.10)nanoparticles were prepared by sol-gel method. Structural characterization by X-ray diffraction (XRD) indicates that the lattice parameter a increases and c decreases linearly with the increase in Mg content (x) due to the substitution of Mg~(2+) for Zn~(2+) in ZnO lattice. The blueshift of Raman modes is observed, impling the increase in force constant of atom vibration in the Mg_xZn_(1-x)O (MgZnO) nanoparticles. Resonant Raman spectra show longitudinal optical phonon overtones up to fifth order, revealing that the short part of the electron-phonon interaction is enhanced and long-range part is weakened by Mg doping.     

Temperature dependence of infrared spectra of (ET)4Hg3I8 crystals; H8- and D8-ET derivatives

Infrared spectra of H₈-(ET)₄Hg₃I₈ and analogous salt with deuterated ET molecule D₈-(ET)₄Hg₃I₈ are studied. Polarized reflectance spectra from single crystals and absorption spectra of powders are measured as a function of temperature. The influence of semiconductor-semiconductor phase transitions on IR spectra is considered. It is observed that the ν₂₇(b_lu) mode of ET molecule couples with electrons.