On hydrogen-bonded complexes: the case of (HF)2

The hydrogen fluoride dimer (HF)₂ is the most completely characterized hydrogen bonded species incorporating a donor molecule and an acceptor molecule. We provide a summary of experimental and theoretical information pertinent to the fundamental and harmonic vibrational frequencies, equilibrium geometry and dissociation energiesD _e andD ₀ as well as a brief critical discussion including some new results on the potential function and current best estimates of experimental quantities.     

Chemical species produced in the reaction between ethanedial (glyoxal) and 5-amino-1,10-phenanthroline and their iron(II) complexes: preparation and some spectrometric studies

Chemical species obtained by reaction of 5-amino-1, 10-phenanthroline with ethanedial (glyoxal) are reported with regard to their preparation, chemical composition and spectrometric characterization (UV-visible, infrared and liquid secondary ion mass spectrometry). Products of the reaction are postulated to be a mixture of species with molecular weights of 339, 371,480 and 524 u. Chemical reactions leading to these products and possible structural formulas for each of these species are presented. The iron complexes of these ligands, because of their extremely low solubility in most solvents, find application as redox mediators when incorporated in carbon paste electrodes, particularly for sensing in continuous-flow systems.     

A vibrational CASSCF study of stretch-bend interactions and their influence on infrared intensities in the water molecule

Summary An extension of the multiconfigurational SCF approach for the resolution of the vibrational problem is presented; it follows the philosophy of the CASSCF method developed in Quantum Chemistry. The new method allows a more complete treatment of anharmonic mode couplings, converges much faster and gives a clearer physical insight of vibrational interactions. This is exemplified by the calculation of infrared transition moments in the H₂O and D₂O isotopomers of the water molecule. It is shown how this property varies with the quality of the wave function when vibrational resonances occur. A detailed analysis by means of this new VCASSCF method demonstrates the crucial importance of excited bending oscillators in the intensity of some pure stretching transitions.Boursier F.R.I.A.     

内噪声作用下的随机共振算法对弱信号的检测

基于随机共振理论提出了一种简便、有效地检测弱信号的方法。在内噪声协同作用下，通过调节输入噪声信号的大小能较好地提高系统输出信号的信噪比，从而实现检测背景噪声很强的弱信号的目的。应用于模拟信号和实验信号的结果证明了方法是可行的。     

Normal coordinate analysis of MSiH3 moieties in transition metal complexes and comparison to results obtained for silyl halides

In order to examine the influence of the transition metal on the metal-silyl fragment MSiH₃ and the metal-silicon bond, polarized Raman spectra of the complexes (C₅R₅)(CO)₂FeSiH₃ R = H (Cp) (1a), Me (Cp^*) (1b)], (C₅H₅)(CO)(PPh₃)FeSiH₃ (1c), (C₅Me₅)(CO)₂RuSiH₃ (2), (C₅R₅)(CO)₂(PMc₃)MoSiH₃ [R = H (3a), Me (3b)], and (C₅R₅)(CO)₂(PMe₃)WSiH₃ [R = H(4a), Me (4b)] have been recorded. The spectral data have been evaluated and interpreted on the basis of a normal coordinate analysis of the MSiH₃ core and the derived force constants and potential energy distributions were compared to results obtained for analogous halogen derivatives in the series XSiH₃ [X = Br (5), I (6)].     

基于支持向量机的羰基化合物红外光谱研究

设计了一个4层分等级分类系统，通过支持向量机技术对羰基化合物的红外光谱成功地进行了信息分类和提取，并与人工神经网络进行比较，结果表明：支持向量机对羰基类化合物红外光谱分类效果优于人工神经网络；另外详细探讨了表征酰胺类化合物的特征光谱峰片段对识圳伯仲叔酰胺的影响，证明了酰胺的N-H伸缩振动峰对识别伯仲叔酰胺贡献最大，为构建红外光谱智能解析系统提供了定量依据。     

FTIR－PAS技术在卟啉类化合物中的应用（Ⅲ）──乙酰丙酮－meso－四－（对－氯代）苯基卟啉稀土配合物的红外光声光谱

研究乙酰丙酮－ｍｅｓｏ－四－（对－氯代）苯基卟啉及其Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｌｕ配合物在３６００～２２０ｃｍ－１范围内的傅立叶变换红外光声光谱，对其主要谱带进行经验归属．实验结果表明，四－（对－氯代）苯基卟啉与稀土乙酰丙酮配合物中的金属离子配位，削弱乙酰丙酮环上的Ｍ－Ｏ键伸缩振动，使该谱带向低波数方向移动．金属敏感带出现在～１５５８、～１４７４、～１４２７、～１２１９、～７９８、～７３３、～２５０ｃｍ－１．     

Temperature and humidity aging of poly(p-phenylene-2,6-benzobisoxazole) fibers: Chemical and physical characterization

In recent years, poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers have become prominent in high strength applications such as body armor, ropes and cables, and recreational equipment. The objectives of this study were to expose woven PBO body armor panels to elevated temperature and moisture, and to analyze the chemical, morphological and mechanical changes in PBO yarns extracted from the panels. A 30% decrease in yarn tensile strength, which was correlated to changes in the infrared peak absorbance of key functional groups in the PBO structure, was observed during the 26 week elevated temperature/elevated moisture aging period. Substantial changes in chemical structure were observed via infrared spectroscopy, as well as changes in polymer morphology using microscopy and neutron scattering. When the panels were removed to an ultra-dry environment for storage for 47 weeks, no further decreases in tensile strength degradation were observed. In a follow-on study, fibers were sealed in argon-filled glass tubes and exposed to elevated temperature; less than a 4% decrease in tensile strength was observed after 30 weeks, demonstrating that moisture is a key factor in the degradation of these fibers.     

On assignment of fundamental vibrational modes of hypophosphite anion and its deuterated analogue

Results of ab initio and density functional theory calculations on the structure and vibrational frequencies of hypophosphite anion indicate earlier experimental assignments of the fundamental vibrational modes are correct while the recent reassignments of several modes proposed by Bickley et al. are inconsistent with the calculated results.     

十六烷基三甲基溴化铵水溶液热致相变的红外光谱研究

在280～320K的温度范围内考察了30％十六烷基三甲基溴化铵水溶液的红外光谱随温度的变化。结果表明该体系的凝聚胶-液晶相转变温度为300K。在300K以下的凝聚胶相,分子的极性头部基团处于高度“固定”的状态,分子的碳氢链以有序的相互平行方式排列,极性头与碳氢链之间有一定的倾斜角。在300K以上的液晶相,极性头内部CH_3-(N~+)基团以及整个极性头与碳氢链之间发生了旋转,碳氢链变为以六方亚晶胞填充形式存在,旦扭曲式构象异构体数量显著增多,极性头与碳氢链之间已不存在倾斜角,分子的亲水极性头和疏水碳氢链部分都处于“融化”状态。