Raman Spectra of Selenium Dioxide at High Pressures

Raman spectra of selenium dioxide at ambient temperature and at pressures up to 10 GPa are reported. There is no evidence of any structural phase transitions in this pressure range, and only minor perturbations of the electronic states are observed. Shifts of normal mode wavenumbers with pressure are used to deduce percentage changes in the principal force constants. Interchain interactions sharply increase with pressure, whereas the stronger interchain forces show smaller increases. the Se-O bonds in side branches slightly weaken as a result of charge transfer to neighbouring bonds. the effects of pressure and temperature on the spectra are briefly compared.     

Symmetry breaking at the phase transitions in ferroelectric pyridinium salts

The phase transitions in ferroelectric pyridinium tetrafluoroborate (PyBF₄) and pyridinium perchlorate (PyClO₄) have been characterized by structural studies. The continuous ferroelectric phase transition at 238.7 K in PyBF₄ appears to be a unique case for multiaxial ferroelectrics, while the first order phase transition in PyClO₄ at 248 K is consistent with the Landau theorem for deducing the character of phase transitions from symmetry considerations. The phase transition in both materials is caused by ordering of the pyridinium cation as well as tetrahedral anions.     

Infrared Spectra of Liquid and Crystalline Ethanol at High Pressures

Abstract

Mid-infrared spectra in the ranges 400–1800 and 2700–4600 cm^?1 of ethanol samples in diamond anvil cells at ambient temperature and pressures up to 11 GPa are reported. The freezing pressure is confirmed to be 1.8 GPa, and, unlike methanol, the resulting solid is crystalline rather than glassy. No further phase transitions are observed in this pressure range. The wave number shifts of 30 selected peaks with pressure are deduced, and their small magnitudes indicate that only minor distortions of the molecules occur. The effects of the strengthening of the intermolecular hydrogen bonds with pressure on the internal modes are briefly discussed.     

Infrared Spectra of Crystalline,Glassy and Liquid Methanol at High Pressures

Abstract

Mid-infrared spectra in the range 400–1800 cm^?1 of methanol samples in diamond anvil cells at ambient temperature and pressures up to 11 GPa are reported. The freezing pressure is confirmed to be 3.6 GPa, and the spectra of the resulting metastable glass are very similar to those of the liquid. When maintained at high pressure, the glass spontaneously transforms to an ordered crystalline phase which is stable over the range 3.6 to 11 GPa. Small changes in peak wavenumbers for 14 internal modes as a function of pressure are observed, indicating that distortion of the molecules is minimal. A slight decrease for the C-O-H bending mode is attributed to charge transfer from the molecular 0-H bond to the strengthening intermolecular hydrogen bond.     

The Vibrational Spectra and Normal Coordinate Analysis of 6Li- and 7Li-Substituted Lithium Disilicate Phases

Infrared and Raman spectra were measured for crystalline ⁶Li- and ⁷Li-substituted lithium disilicate. The spectra were analysed by normal coordinate analysis (NCA) using a modified valence force field. The resulting force constants were consistent with those calculated for related SiO₂-containing phases. The Raman spectral results for related glasses were interpreted with respect to the spectral data for the crystalline phase.     

碳炔分子红外振动光谱的理论模拟研究

碳炔分子具有不同的结构，相应的红外谱图具有不同的振动吸收峰位。本文以GAUSSIAN98计算程序在HF水平选用6—31 G(d，p)基组对两种不同结构碳炔的红外光谱进行理论模拟计算。结果表明两种不同结构的碳炔分子的红外振动吸收峰位存在差异，不同共轭碳链长度影响红外吸收峰的峰位和峰强度。计算结果可应用于碳炔材料红外谱图的谱峰归属和分析。     

氨基酸DLH及其稀土镧配合物的高压红外和拉曼光谱研究

测定了DL-2-氨基-4-磺酸基-丁酸 [DLH, DL-Homocysteic acid, (NH+₃)-CH(COOH)-(CH₂)₂-SO-₃] 及其稀土La配合物[La(DLH)₂Cl₃·H₂O=LaL₂]在不同压力下的红外和拉曼光谱。DLH 在50 kbar左右压力以下存在两个压力诱导相转变区,它们分别在17和37 kbar左右,两者均为二级相转变,认为分子间氢键的存在是出现两个压力诱导相转变区的原因。在红外光谱中,SO-₃的对称伸缩振动的压力灵敏度(dν/dp)表现出与其他振动模式不同的变化趋势,它们在低压相区的平均压力灵敏度为0.30 cm-1·(kbar)-1、中压相区为0.32 cm-1·(kbar)-1、高压相区为0.41 cm-1·(kbar)-1,低压相区与高压相区的比值为0.72, 而其他振动模式刚好相反,低压相区与高压相区的比值为4.8。稀土La配合物LaL₂的生成,改变了分子间的氢键,在50 kbar左右压力以下只观察到1个压力诱导相转变区(27 kbar附近)。在红外光谱中,配合物LaL₂中SO-₃的反对称伸缩振动的压力灵敏度(dν/dp)也表现出与其他振动模式不同的变化趋势,它们在低压相区的平均压力灵敏度与高压相区的平均压力灵敏度的比值为0.43, 而其他振动模式的比值为2.5。     

红外光谱中取代基对苯环骨架振动吸收峰的影响规律

本文初步地探讨了单取代及对位双取代对苯环骨架振动吸收峰频率和强度的影响规律 ,得出结论 :1给电子单取代基随给电子能力增强使苯环骨架振动吸收峰 16 0 0 cm-1增强 ,而吸电子基则相反。 2卤素作为单取代基时 ,使苯环骨架伸缩振动产生强红外吸收峰 ;且随卤素电负性增强吸收峰频率向高波数移动。 3对位取代基为不同类型时 ,16 0 0 cm-1处显强峰 ,而为同一类型时 ,当电子效应相近或相同时 ,16 0 0 cm-1处吸收峰很弱或根本无吸收峰。并讨论了产生这些现象的原因。     

高胆固醇血样的红外吸收光谱研究

红外光谱法及与其相关技术的应用研究,促进了光测技术的迅猛发展。文章针对血液的红外光谱分析这一重要课题, 提出了血液的红外吸收光谱分析新技术, 通过在一定的频谱范围内对正常血样与异常血液的红外吸收光谱进行实验测量和分析, 可以判断血样是否异常,其实验和分析方法具有一定的先进性。文章中研究了正常血样和高胆固醇血样的红外吸收光谱之间的差别, 并给出了人的正常血清与高胆固醇血清的红外吸收光谱以及分析结果,研究结果表明它们的吸收率、吸收峰位置以及吸收率之比之间的差别可以作为检验正常血样与异常血样的依据,从而为应用于疾病诊断方面提供了重要的参考。     

烟度红外光谱的分析法

本文分析了柴油发动机废气中各种成分的红外光谱特征，应用红外光路系统直接对烟度进行测量，结果表明，本法测量动态范围宽，线性好，精度高，误差小（误差≤1．0％），相对于其他烟度分析方法具有一定优势。     

金属钨三键多核金属有机配合物高压拉曼及红外光谱研究

研究了金属钨三键多核金属有机配合物 [Cl(CO) 2 (DPPE)WCC6 H4CCC6 H4NC]2 ReCl(CO) 3(DPPE =bis(diphenylphosphino)ethane,(Ph) 2 PCH2 CH2 P(Ph) 2 )不同压力下的拉曼和红外光谱 (最高压力约 5 0kbar)。配合物在 3 0kbar存在一压力诱导二级相变。金属钨三键伸缩振动ν(WC)压力相关 (dν/dp)在低压相区 ( 0 5 9cm-1·(kbar) -1)与高压相区 ( 0 0 4cm-1·(kbar) -1)差别很大 (约 15倍 )。在高压下 ,从基团Cl(CO) 2 (DPPE)WC中的金属钨W向COπ 轨道的π 反馈明显增强 ,WC的键强度减弱 ,力常数减小和ν(WC)降低 ;此效应与压力缩短WC键 ,增大力常数和增加ν(WC)的效应互相竞争。     

Neutral to Ionic Pressure-Induced Phase Transition in the Mixed Stack Charge-Transfer Crystal ClMePD-DMeDCNQI

In the present work we report a spectroscopic investigation of the pressure-induced neutral to ionic (NI) phase transition in the mixed stack charge-transfer crystal 2-chloro-5-methyl-p-phenylenediamine 2,5-dimethyl-dicyanoquinonediimine, ClMePD-DMeDCNQI. The pressure induced phase change is studied by calculating, from spectroscopic data, the degree of ionicity, 𝜌 , which undergoes a continuous change as a function of pressure, reaching a value of about 0.65 at 3 GPa. The NI crossing reveals unique properties with respect to previously studied cases on similar compounds.     

近红外光谱分析中应考虑的几个问题

近年来红外光谱分析技术得到了迅速的发展,原因在于它能够有效地提供关于样品的定性和定量信息。但是,在进行近红外光谱分析时,应考虑样品的特征、分析实验的设计及数据处理等多方面的问题,以取得更 可靠的分析结果。     

20种活血化瘀中药提取物的红外光谱分析及其与药性相关性的初步探讨

为探讨中药提取物红外光谱用于中药药性识别的可行性,分别采用石油醚、乙酸乙酯、无水乙醇、水4种溶剂分部位提取桃仁等20种不同药性活血化瘀中药的化学成分,并用FTIR技术对各溶剂提取得到的成分进行分析测定,共采集得到240个傅里叶变换红外图谱。经对原始数据预处理后,应用主成分分析结合支持向量机方法对各样本的IR图谱进行分析。结果显示用乙酸乙酯提取物的红外光谱构建的模型对平性药识别正确率为80%,对非平性药的识别正确率为90%,平均识别正确率为85%。     

碲化铅晶体的红外光谱测量

红外等离子反射光谱与晶体材料的载流子浓度、迁移率和有效质量等参数有关。通过测量碲化铅晶体的红外反射光谱可以比较、分析不同晶体的性能,从而可选出低浓度、高迁移率的优质材料。     

三羟甲基甲胺、季戊四醇及其二元体系固-固相变的变温红外光谱研究

利用傅里叶变温红外光谱仪分别测定了三羟甲基甲胺（TAM）、季戊四醇（PE）及其二元体系变温红外谱。实验表明，多元醇分子中羟基吸收峰随温度升高耐发生位移向高波数移动，此结果既能反映多元醇及其二体系固－固相变的温度区间，又与转变热相对应，从而揭示了多元醇及其二元体系固－固相变贮热的机理。     

Solid and Liquid AgI at High Pressure and High Temperature: A X-ray Absorption Spectroscopy Study

We report about recent X-ray absorption spectroscopy (XAS) measurements on solid and liquid AgI under high pressure. The structural behaviour of AgI has been investigated to pressures P～4.3 GPa at room temperature and to P～1.8 GPa at 1100 K. The high temperature/high pressure conditions have been obtained by means of a large-volume press of the Paris-Edinburgh type, coupled with a 10 mm boron/epoxy biconical gasket. The absorption spectra have been collected in transmission mode, both at the K-edge of Ag and I, and the samples have been characterized in situ by energy scanning X-ray diffraction at fixed angles. Our XAS results for solid AgI are compatible with previous X-ray diffraction measurements. For liquid AgI, we observe a slight change in the intensity and a shift in the frequency of the XAS oscillations with respect to what obtained in the case of the ambient pressure liquid.     

中成药速效救心丸的红外光谱聚类分析研究

对同一厂家同一批号和不同批号的速效救心丸的红外图谱进行了测定,对影响红外光谱测定的实验条件包括粒度和混合比例进行了优化选择。实验结果表明,该方法具有很好的精密度、重复性和稳定性;采用模式识别中的聚类分析,对同一批号和不同批号的速效救心丸进行了分析比较,结果表明,同一批号的速效救心丸样本的红外图谱具有良好的重复性,当相关系数达到0.992时,所分析的60个样本聚为一类,说明该厂家同一批号及不同批号速效救心丸的产品质量具有较好的稳定性,红外光谱法结合聚类分析法可以简便快速地完成对中成药制剂的质量评价。     

Infrared and Raman Spectra of Solid Guanine Derivatives. 7-METHYLGUANINE, 9-METHYLGUANINE, 9-ETHYLGUANINE, 1,7-DIMETHYLGUANINE,and 1,9-DIMETHYLGUANINE.

The infrared and Raman spectra of 7-methylguanine, 9-methylguanine, 9-ethylguanine, 1,7-dimethylguanine, and 1,9-dimethylguanine in the solid state have been reported and discussed. Hydrogen bonds in these solid guanine derivatives bring about strong perturbations which are discussed in terms of structural data given by X-ray diffraction methods. The spectra of guanine and 9-methylguanine are compared with the spectra of the monomers isolated in low-temperature matrices.     

二(2-乙基己基)磷酸稀土配合物的红外和拉曼光谱

用稀土氯化物与二(2-乙基己基)磷酸反应制备了14种标题配合物,测定了配合物的红外和拉曼光谱,对其主要红外和拉曼谱带进行了归属.结果表明,Ln(DEHP)3应具有与Sm(DMP)3和Pr(DMP)3相同的配位形式和结构类型,每个稀土离子通过双O-P-O桥与邻近的三个稀土离子相连接,形成"双桥二十四元环"的多聚网络结构.Ln-O键基本上是离子键.