Vibrational assignment, <Emphasis Type="Italic">ab initio</Emphasis> calculation and normal coordinate analysis of 2,2′-biquinoline

The vibrational wavenumbers and the fundamental modes of 2,2′-biquinoline were obtained by density functional theory (DFT) with the B3LYP functional using the 6-31G(d,p) basis set. The calculated wavenumbers were scaled by a single factor of 0.965 to correct them for vibrational anharmonicity, but the force constants were overestimated. Normal coordinate analysis of the molecule was also carried out by using the force field of the quinoline molecule and the force field parameters of quinoline are shown to be transferable to 2,2′-biquinoline. The potential energy distribution associated with the normal modes is also given. The theoretical wavenumbers are found to be in good agreement with the experimental data.     

多孔硅的电化学制备

单晶硅在氢氟酸溶液中阳极氧化可制得多孔硅, 多孔硅是一种以新形态存在的硅, 与单晶硅相比, 它表现出独特的物理性质和化学活性。荧光光谱峰的蓝移表明, 在p-型低掺杂衬底硅上形成的多孔硅中存在量子尺寸效应, 新近获得的Raman光谱也证实了这一点。     

人工神经网络及其在分析化学中的应用

人工神经网络是一种新兴的计算方法，有着广阔的发展前途，目前在分析化学领域已经有了多方面的应用。本文简要介绍了人工神经网络的原理及其在分析化学中的应用。     

傅立叶变换红外光谱对灰指甲组织结构的研究

对健康指甲和灰指甲的红外光谱特征吸收峰进行了指认,并对其相应官能团的吸收峰进行了对比分析.结果表明,灰指甲增厚、变脆的原因系α-角蛋白螺旋结构遭到破坏,肽链伸展并发生断裂,形成了不同化学环境的氨基酸,同时蛋白质分子的有序排列也发生了改变.     

Multivariate calibration of near infrared spectra by orthogonal WAVElet correction using a genetic algorithm

Orthogonal WAVElet correction (OWAVEC) is a pre-processing method aimed at simultaneously accomplishing two essential needs in multivariate calibration, signal correction and data compression, by combining the application of an orthogonal signal correction algorithm to remove information unrelated to a certain response with the great potential that wavelet analysis has shown for signal processing. In the previous version of the OWAVEC method, once the wavelet coefficients matrix had been computed from NIR spectra and deflated from irrelevant information in the orthogonalization step, effective data compression was achieved by selecting those largest correlation/variance wavelet coefficients serving as the basis for the development of a reliable regression model. This paper presents an evolution of the OWAVEC method, maintaining the first two stages in its application procedure (wavelet signal decomposition and direct orthogonalization) intact but incorporating genetic algorithms as a wavelet coefficients selection method to perform data compression and to improve the quality of the regression models developed later. Several specific applications dealing with diverse NIR regression problems are analyzed to evaluate the actual performance of the new OWAVEC method. Results provided by OWAVEC are also compared with those obtained with original data and with other orthogonal signal correction methods.     

关于meso—四苯基卟啉在冰醋酸中的存在形式

前言卟啉在生物化学、分析化学、药物化学等领域有着广泛研究和重要应用［１～３］。近年来虽然对卟啉类化合物的研究报道很多［４～６］，但对卟啉在酸性介质中的研究很少。较早期的研究工作认为卟啉类化合物在酸性介质中仅以其二酸形式存在［７］。本文实验结果显示ｍｅ...     

2-三氰基乙烯基蒽及其旋转异构体的量子化学研究

用量子化学从头算方法 ,在RHF/STO - 3G水平上 ,对 2_三氰基乙烯基蒽 (2_TCVA)分子进行了理论计算 ,优化得到了它的平衡几何构型 ,并计算了它的谐振动频率 .结果表明 :2_TCVA存在两种旋转异构体 :2_TCVA(1)和 2_TCVA(2 ) ,2_TCVA(2 )的总能量比 2_TCVA(1)的略高 .在PM3/CIS水平上计算了它们的电子光谱 ,得到了由基态到各激发态的垂直跃迁能和相应的振子强度 .研究表明 :2_TCVA(1)和 2_TCVA(2 )的强度最大的吸收波长分别为 2 4 9.72nm和 2 89.4 1nm ,2_TCVA(2 )的强度最大的吸收波长比 2_TCVA(1)的要长 .计算结果与实验结果符合得较好     

Improved accuracy of quantitative XPS analysis using predetermined spectrometer transmission functions with UNIFIT 2004

The accuracy of quantitative XPS analysis can be improved using predetermined transmission functions. Two different calibration methods are used for estimating the transmission function T(E) of a photoelectron spectrometer, applying a survey spectra approach (SSA) and a quantified peak‐area approach (QPA) to minimize the quantification error. For the SSA method, Au, Ag and Cu spectra measured with the Metrology Spectrometer II have been used. The new QPA method was built up from Au 4f, Au 4d, Au 4p_3/2, Ag 3d, Ag 3p_3/2, Cu 3p, Cu 2p_3/2, Ge 3p and Ge 2p_3/2 standard peak areas, applying adequate ionization cross‐sections and mean free path lengths for different pass energies (10 and 50 eV), lens modes (large area, large area XL, small area 150) and x‐ray sources (Al/Mg Twin and Al Mono). In the energy range 200–1500 eV a transmission function T(E) = a₀ + b₁E (where a₀, b₁ and b₂ are variable parameters) was found to give an appropriate approximation for eight tested spectrometer settings, implementing the largest changes in the case of pass energy variations. Determination and application of the transmission functions were integrated in the XPS analysis software (UNIFIT 2004) and tested by means of an Ni90Cr10 alloy. The results demonstrate the practicability of the SSA and QPA methods, giving decreased errors of <8% in comparison with errors up to 38% obtained using Wagner's sensitivity factors. Copyright © 2005 John Wiley & Sons, Ltd.     

钙钛矿型CaSiO_3解压缩和重压缩过程的分子动力学模拟

用分子动力学模拟方法 (MD)研究了 3 0 0K时钙钛矿型CaSiO3 ,从高压到负压的解压缩过程 .MD模拟获得的P V关系与实验数据相近 ,与已报道的MD模拟数据基本一致 ,所得体积模量也在实验数据分布范围内 .减压缩和重压缩的MD模拟数据与实验结果相似 .钙钛矿型CaSiO3 解压缩成非晶态时 ,存在两个结构破坏阶段 :破坏硅氧八面体和破坏钙氧二十面体 .当钙氧二十面体被破坏后 ,重压缩不能得到钙钛矿型结构 .只要钙氧二十面体未被破坏 ,重压缩可恢复钙钛矿型结构 .本研究得到的结果尚未见相关报道 .由MD模拟数据计算了CaSiO3 系统的红外光谱 ,分析这些数据可知钙钛矿型CaSiO3 解压缩非晶化是一个二阶软模相变 .研究表明钙钛矿型CaSiO3 结构存在一个等容的亚稳极限 ,其解压缩非晶化是一个受动力学控制的亚稳状态 .     

5,9,14,18,23,27,32,36-八烷氧基2,3-萘酞菁镍(Ⅱ)的结构与光谱性质关系的研究

测定了一组八烷氧基萘酞菁镍（Ⅱ）配合物Ni（Ⅱ）（RO）8NPC（R＝C4H9，C8H17，C12H25，NPC＝C48H16N8）在5种有机溶剂（Py、DMSO、DMF、CH2Cl2、C6H12）中的电子吸收光谱和荧光光谱，研究了这些配合物的结构与光谱的关系。结果表明该系列RO取代萘酞菁镍（Ⅱ）配合物的Q带吸收光谱比无取代的红移75nm左右，荧光光谱屯相应红移50～80nm，而溶剂对其影响不大。