Influence of doping on the dynamical properties of III–V–N by Raman scattering, infrared absorption and model calculations

In the framework of a rigid-ion model and using realistic Greens function theory, we have studied systematically the influence of doping on the lattice dynamics of III–V-nitrides. Our theoretical analysis is based on a sound physical appeal for the perturbation caused by different dopants in compound semiconductors. After analyzing the dynamical behavior for two sets of impurities with closest masses occupying Ga- and As-sites in GaAs, we have proposed simple empirical relationships providing corrections to the impurity–host interactions for isoelectronic defects and for dopants carrying static charges. Despite the simplicity of perturbation models, our Greens function theory provided results in good agreement with the recent Fourier-transform infrared (FTIR) absorption data for the magnitude and splitting of N-isotopic shifts of localized vibrational modes in GaAs. With high-resolution FTIR spectroscopy, we strongly believe that the ¹⁴N_As-related broad local mode (471 cm⁻¹) in GaAs can be resolved into fine structures due to Ga-host isotopes. Theoretical results for the in-band modes of As_N in cubic gallium nitride are compared and discussed with the existing Raman data on molecular beam epitaxy (MBE) grown GaN layers on GaAs substrates, as well as on GaN samples intentionally doped with As.     

定量分析被动FTIR遥感污染云团的探测极限

在建立大气模式下污染云团红外光谱仿真模型的基础上,利用LOWTRAN或MODTRAN所提供的Subarctic Winter大气模式,仿真出几种特殊的污染云团红外光谱,详细讨论了该模式下的仿真结果与U.S.Standard模式下的仿真结果的差别,并给出在Subarctic Winter大气模式下被动傅立叶变换红外光谱辐射仪遥测污染云团的探测极限。     

不同服役年限下动车组绝缘子表面憎水特性研究

选取不同运行年限的动车组车顶绝缘子为研究对象,分别对其进行憎水性分析(接触角法)、傅里叶红外分析和扫描电镜分析。结果表明:随着服役时间的增加,绝缘子的憎水性下降迅速,但下降趋势逐年减缓,顶部伞裙的憎水性普遍低于中部伞裙与底部伞裙,这与FTIR分析的绝缘子中Si-CH3含量变化趋势吻合。随着服役年限的增加,绝缘子表面形貌变化明显,服役6年的动车组绝缘子已与110 kV输电网中服役15～19年的绝缘子微观形貌相似,这是动车组绝缘子憎水性老化速度快于输电网绝缘子的重要原因之一。     

Design and Development of a Bimodal Optical Instrument for Simultaneous Vibrational Spectroscopy Measurements

Vibrational spectroscopy techniques are widely used in analytical chemistry, physics and biology. The most prominent techniques are Raman and Fourier-transform infrared spectroscopy (FTIR). Combining both techniques delivers complementary information of the test sample. We present the design, construction, and calibration of a novel bimodal spectroscopy system featuring both Raman and infrared measurements simultaneously on the same sample without mutual interference. The optomechanical design provides a modular flexible system for solid and liquid samples and different configurations for Raman. As a novel feature, the Raman module can be operated off-axis for optical sectioning. The calibrated system demonstrates high sensitivity, precision, and resolution for simultaneous operation of both techniques and shows excellent calibration curves with coefficients of determination greater than 0.96. We demonstrate the ability to simultaneously measure Raman and infrared spectra of complex biological material using bovine serum albumin. The performance competes with commercial systems; moreover, it presents the additional advantage of simultaneously operating Raman and infrared techniques. To the best of our knowledge, it is the first demonstration of a combined Raman-infrared system that can analyze the same sample volume and obtain optically sectioned Raman signals. Additionally, quantitative comparison of confocality of backscattering micro-Raman and off-axis Raman was performed for the first time.     

普鲁士兰恒电流法沉积在聚苯胺膜上的性能表征

在ITO玻璃上分别用循环扫描伏安法和恒电流法依次沉积了聚苯胺(PANI)和普鲁士兰(PB)薄膜,对PANI和PB单层膜及复合膜的红外光谱进行了分析,讨论了3种薄膜的循环伏安曲线和紫外-可见吸收光谱.结果表明,在所选沉积条件下,制备出了电活性高的电致变色复合薄膜,600nm处的着色效率η=57.3.用钾离子掺杂的聚(2-丙稀酰胺-2-甲基丙磺酸)(PAMPS)作为离子导体,电导率σ达到8.691×10-3S/cm,组装的器件循环50次后,CV曲线变化较小,性能稳定.     

基板支撑梢对TFT栅界面SiN_x和a-Si成膜特性的影响

采用等离子体增强化学气相沉积法(PECVD)制得氮化硅和氢化非晶硅薄膜,对PECVD设备中基板支撑梢区域的膜质进行了研究。结果显示基板支撑梢对氮化硅薄膜的影响是:基板支撑梢区域的膜厚(沉积速率)高于非基板支撑梢区域,氢含量及[SiH/NH]值高于非基板支撑梢;对氢化非晶硅薄膜的影响是:基板支撑梢区域的膜厚(沉积速率)小于非基板支撑梢区域,氢含量高于非基板支撑梢。并对成膜影响的机理进行了分析讨论。     

烃源岩中可溶有机质的FTIR地球化学意义探讨——以准噶尔盆地下二叠统风城组为例

为进一步拓展显微傅里叶红外光谱（FTIR）技术在有机地球化学研究中的应用,以准噶尔盆地下二叠统风城组碱湖相含油气系统为例,开展了沉积有机质的生烃研究。结果表明,7组红外官能团具有指征意义,并据此提出3个红外结构新参数,即A指数（A_{2 920}/A_{3 600}）、B指数（A_{2 920}/A_{1 460}）和C指数（A_{1 140}/A_{1 600}）。A指数揭示盐岩区烃源岩具有更高的生烃潜力,B指数揭示可能存在热液流体影响导致盐岩区有机质具有异常的热演化,而C指数表明从边缘区到盐岩区,随盐度的升高,有机质的分子聚合受到影响。据此,位于沉积中心的盐岩区油气勘探潜力较大,尽管在深层可能仍存在轻质原油。这些认识为区域油气勘探提供了新的参考资料,展示了FTIR技术能为传统的有机地球化学研究提供补充,具有广阔的应用潜力。     

Stabilizing effect of the cyclodextrins additive to spray-dried particles of curcumin/polyvinylpyrrolidone on the supersaturated state of curcumin

Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD.     

基于憎水迁移性测试的复合绝缘子老化特性

憎水迁移性作为复合绝缘子状态评价和老化程度判断的关键参数,有着重要的研究意义。为此,以在我国南方地区运行多年的直流复合绝缘子为研究对象,采用静态接触角法进行了系统的憎水迁移性测试,同时应用傅里叶变换红外光谱和X射线光电子能谱分析深入探究了硅橡胶材料的微观结构变化。研究结果表明:绝缘子伞裙上表面的边沿憎水迁移性最差,根部憎水迁移性最好,绝缘子不同方位的憎水迁移性也有所差异;老化最为严重的边沿褪色位置有机官能团含量大幅下降,Si元素和C元素减少、Al元素增加,并且检测出硅橡胶体系交联度的明显上升。上述憎水迁移性以及微观分析的研究结果可为直流复合绝缘子老化机制和老化程度评估提供依据。     

Portable Infrared Spectrometer to Characterize and Differentiate Between Organic and Conventional Bovine Butter

The performance of a portable infrared system combined with pattern recognition to discriminate between organically and conventionally produced bovine butter samples as well as to predict the levels of conjugated linoleic acid (CLA) were evaluated. Sixty butter (27 organic and 33 conventional) samples were used in this study. Bovine butter–fat were applied onto an attenuated total reflectance infrared (ATR‐IR) accessory equipped with a five‐bounce ZnSe crystal set at 65 °C for spectral collection. In addition, ATR‐IR spectra of bovine butter were directly collected at room temperature to avoid phase separation. The fatty acid profile and the levels of CLA were determined using reference FAME‐GC‐FID analysis. SIMCA models showed well separated clusters that discriminated between organic and conventional bovine butters due to C=C trans bending out of the plane vibration modes band at 967 cm^?1. Additionally, strong PLSR models were developed to predict CLA levels using butter–fat and bovine butter spectra with SEP of 0.05 % and RPD of 4.7, indicating that the models are suitable for quality control applications. Portable IR technology offers the ability for “in situ” analysis of butters that is much less time consuming than current analytical practices for authentication and quality control efforts by the industry.