Infrared spectra of geminal and novel triple hydroxyl groups on silica surface

We investigated the O---H stretching frequencies of geminal and triple hydroxyl groups on silica surface by FT-IR spectroscopy. The geminal and triple hydroxyl groups were individually prepared by the chemical reaction of alkylchlorosilane with surface isolated hydroxyl groups which are separated enough and following hydroxylation of surface chlorine groups. The O---H stretching frequencies of these generated geminal and triple hydroxyl groups were observed at frequencies by 2 and 3 cm⁻¹ lower than that of isolated ones, respectively. By heat treatment the triple hydroxyl groups are firstly eliminated, and secondly the geminal hydroxyl groups disappear. Lastly only isolated hydroxyl groups remain on silica surface.     

Infrared absorption spectra of As-Se glasses

IR absorption spectra of As-Se glasses have been studied over a wide range of compositions. Various two-phonon, multiphonon (combination tones) and impurity absorptions have been identified. Compositional variation of relative band intensities has been explained in terms of the chemically ordered network model.     

Polarization Dependent Time-Resolved Infrared Spectroscopy and Its Applications

Polarization dependent time-resolved infrared (TRIR) spectroscopy has proven to be a useful technique to study the structural dynamics in a photochemical process. The angular information of transient species is obtainable in this measurement, which makes it a valuable technique for the investigation of electron distribution, molecular structure, and conformational dynamics. In this review, we briefly introduce the principles and applications of polarization dependent TRIR spectroscopy. We mainly focused on the following topics: (i) an overview of TRIR spectroscopy, (ii) principles of TRIR spectroscopy and its advantages compared to the other ultrafast techniques, (iii) examples that use polarization dependent TRIR spectroscopy to probe a variety of chemical and dynamical phenomena including protein conformational dynamics, excited state electron localization, and photoisomerization, (iv) the limitations and prospects of TRIR spectroscopy.     

Formation and spectra of clathrate hydrates of methanol and methanol-ether mixtures

Infrared spectra of mixed clathrate hydrates, with either ethylene oxide (EO) or tetrahydrofuran (THF) and methanol molecules as the guest species, have been obtained from thin films prepared by vapor deposition of D₂O mixtures in the 115–130 K range. Although methanol acts as a suppressant to the direct vapor deposition of a type I clathrate with EO, nearly complete conversion of 115 K amorphous codeposits, to the crystalline mixed clathrate, occurs upon warming near 150 K. By contrast, the type II clathrate of THF shows an increased crystalline quality when methanol is included in the vapor deposits of the mixed clathrate hydrate at 130 K. The observation of the O---D stretch-mode band of weakly bonded CD₃OD near 2575 cm⁻¹ is part of the evidence that the methanol molecules are encaged. However, as shown theoretically by Tanaka, the clathrate hydrates of methanol, even when mixed with an ether help gas, are not stable structures but form at low temperatures because of kinetic factors, only to decompose in the 140–160 K range. Attempts to prepare a simple type I or type II clathrate hydrate of methanol have produced mixed results. Limited amounts of clathrate hydrate form during deposition but annealing does not result in complete conversion to crystalline clathrates, particularly for host : guest ratios of 17 : 1.     

炸药爆轰合成纳米石墨的红外光谱研究

石墨是碳材料中最常见的结晶状态,它具有耐高温、抗腐蚀、自润滑、无毒及价格低廉等特点,广泛应用于润滑剂和添加剂等方面^[1].由于高纯纳米石墨粉在某些高新技术领域中有较好的应用前景,近些年来得到开发和应用,如制成复合导电材料、吸波材料及储氢材料等^[2].以前有学者用纳米金刚石粉加热相转变^[3]和高能球磨^[4,5]的方法制备了纳米石墨,在制备碳纳米管时也有石墨的纳米粒子生成^[6].但用这几种方法制备纳米石墨,既费时又消耗较大能量,成本非常高.     

Infrared and Raman spectra of 2,4-dimethylaniline

The infrared spectra of 2,4 dimethylaniline have been recorded in the region 3600-100 cm⁻¹. The Raman spectra with polarization measurements have been recorded and investigated for the first time in the region 3500-100 cm⁻¹. New frequency assignments have been proposed assuming the molecule to possess an approximateC ₂ symmetry. Fifty normal modes of the molecule, out of a possible fifty four modes, have actually been observed and assigned including twenty seven hitherto unreported frequencies. The observed spectral changes give evidence of the presence of an intermolecular hydrogen bonding of an N−H...N type, and suggest a solid-solid phase transition between 223 and 123 K in the molecule.     

Infrared and infrared emission spectroscopy of the zinc carbonate mineral smithsonite

Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440cm(-1) is assigned to the nu(3) CO(3)(2-) antisymmetric stretching vibration. An additional band is resolved at 1335cm(-1). An intense sharp Raman band at 1092cm(-1) is assigned to the CO(3)(2-) symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442cm(-1) shifting to lower wavenumbers with thermal treatment. A band observed at 870cm(-1) with a band of lesser intensity at 842cm(-1) shifts to higher wavenumbers upon thermal treatment and is observed at 865cm(-1) at 400 degrees C and is assigned to the CO(3)(2-)nu(2) mode. No nu(2) bending modes are observed in the Raman spectra for smithsonite. The band at 746cm(-1) shifts to 743cm(-1) at 400 degrees C and is attributed to the CO(3)(2-)nu(4) in phase bending modes. Two infrared bands at 744 and around 729cm(-1) are assigned to the nu(4) in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO(6) octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991cm(-1) in both the IE and infrared spectra are attributed to combination bands.     

Infrared spectra of two sexithiophenes in neutral and doped states: a theoretical and spectroscopic study

The FT-infrared spectra of two sexithiophenes having their end ,′-positions substituted by n-hexyl or -thiohexyl groups, in neutral and doped states, are studied with the main aim of deriving information about the π-electrons delocalization and about the electronic structure of the charged defects created upon doping with iodine. The analysis of the experimental data is aided by Density Functional Theory calculations. The modifications in the electronic structure of the sexithiophene backbone induced by the n-thiohexyl encapsulation are discussed from the point of view of single molecule interactions in thiol-terminated π-conjugated oligomers bound to metallic or cluster electrodes.     

二茂铁填充的双壁碳纳米管的合成与红外光谱表征

通过气相法将二茂铁填充到双壁碳纳米管的纳米空腔内部, 制备了一种新型纳米杂化材料——二茂铁-双壁碳纳米管. 对这种纳米材料进行了高分辨透射电子显微镜结构分析与傅立叶变换红外光谱表征. 红外光谱研究结果表明, 碳纳米管管壁与内部二茂铁之间存在强的电子相互作用,并伴有电子转移.     

Quantitative Determination of Fluconazole by Infrared Spectrophotometry

Abstract

The purpose of the study was the quantitative determination of fluconazole by IR spectrophotometry which was realized by the application of the KBr disc technique. In this study dehydrocholic acid was used as internal standard.

The absorption bands at 960 and 675 cm^?1 were chosen for fluconazole and 1705 cm^?1 for dehydrocholic acid. The concentration range between 0.4–1.6% w/w in KBr disc showed compliance with Beer's law.

Besides IR spectroscopy, UV spectroscopy and HPLC methods were also used In the quantitative determinations. In the UV spectroscopy method the absorbance value at 261 nm in MeOH was used for fluconazole. In quantitative determinations which were performed by using HPLC, ketoconazole was the internal standard. Different regression equations were applied for each method in order to complete the quantitative determination. In UV spectroscopy and HPLC methods, relative standards were found as 0.74, 1.04% and in IR spectroscopy (675, 960 cm^?1) relative standards were found as 1.1 and 1.51%, respectively.     

红外反射光谱法在金属表面光洁度表征中的应用

本研究利用傅里叶变换红外反射光谱技术,通过对比不同光洁度的金属表面红外反射光谱图,建立了利用傅里叶变换红外反射光谱表征金属表面光洁度的方法,本文从红外反射光谱图4000cm-1～600cm-1、3400cm-1～2600cm-1波段的斜率及4000cm-1、3000cm-1、2000cm-1波数处的反射率两方面进行考察,结果表明,斜率和某一波数处的反射率均能用来表征金属表面的光洁度,且具有较高的准确性。     

Infrared and Raman spectra and thermodynamic functions of 4-methoxypyridine N-oxide

The infrared spectrum of 4-methoxypyridine N-oxide in the region 4000-30 cm⁻¹ in the solid and liquid states and the polarized laser Raman spectrum of the molecule in the liquid state have been investigated. A vibrational assignment of the observed frequencies based on the state of polarization of the Raman lines and comparison with the related molecules is presented. Ideal gas state thermodynamic functions of the molecule are calculated in the temperature range 273·15–1500° K.     

Metal Ion‐Assisted Infrared Optical Sensor for Selective Determination of Tryptophan in Urine Samples

In this study, a simple infrared chemical sensor was developed for the selective detection of tryptophan in biological fluids. This sensor was capable of trapping tryptophan molecules through the formation of relatively stable metal ion complexes on the surface of the sensing element. A proline‐modified sensing phase was immobilized on the surface of the internal reflection element. With the assistance of appropriate metal ions, tryptophan molecules were selectively attracted nearby the evanescent field such that analytical signals were generated. Factors that affected the chemical equilibria in this detection system were examined including the species and concentration of metal ion, the pH of the sample solution, and the concentration of the chelating agent. Among the examined metal ions, nickel provided the best selectivity toward the detection of tryptophan as a result of its extremely high formation constant with tryptophan. Under the optimal conditions, the detected signals were related linearly (R² > 0.99) to concentrations of tryptophan up to 600 μM. Based on three times the baseline variation of blank samples, the detection limit was ca. 5 μM. From a study of possible interfering agents—metal ions and organic species—in the sample solution, the recoveries of tryptophan were greater than 95%.     

红外光谱法对六氟磷酸锂的快速定量分析

本文建立了一种用傅里叶红外光谱(FT-IR)法快速定量分析LiPF6的方法。采用红外光谱(IR)法和X射线衍射(XRD)法对LiPF6样品进行了定性分析。选取LiPF6红外光谱847cm-1处的特征吸收峰为分析对象,利用吸光度峰面积积分法进行定量分析,由标准曲线可知,LiPF6的含量与其红外光谱特征峰的吸收强度有很好的线性关系,相关系数达0.9998,线性范围在0.04～25mg.mL-1,检出限可达0.02mg.mL-1。LiPF6样品定量测定的相对标准偏差(RSD)约为0.18%,回收率为96%～98%。     

Infrared spectra of (CH3)2O and (CH3)2O + H2O at low temperature

Fourier transform infrared reflection spectroscopy (incidence angle of 5°) was used to characterize thin films of dimethyl ether (DME) and of mixtures containing water and DME between 10 and 160 K under a pressure of 10⁻⁷ mbar. Solid DME has two solid phases: an amorphous phase which is obtained below 65 K and a crystalline phase >65 K. From 90 K, DME begins to sublimate with surface binding energy of 20±2 kJ mol⁻¹. Vibrational spectrum of DME trapped in water ice remains nearly unchanged from 30 to 120 K. Between 120 and 130 K, a large part of DME is released and strong changes in the frequencies and the profile of the absorptions of DME are observed. This behavior suggests the formation of clathrate hydrate. Below 120 K, the trapped DME is hydrogen-bonded to water molecules.     

Infrared Photodisssociation Spectroscopy of Boron Carbonyl Cation Complexes

The boron carbonyl cation complexes B(CO)₃⁺, B(CO)₄⁺ and B₂(CO)₄⁺ are studied by infrared photodissociation spectroscopy and theoretical calculations. The B(CO)₄⁺ ions are characterized to be very weakly bound complexes involving a B(CO)₃⁺ core ion, which is predicted to have a planar DD_3h structure with the central boron retaining the most favorable 8-electron configuration. The B₂(CO)₄⁺ cation is determined to have a planar D_2h structure involving a B-B one and half bond. The analysis of the B-CO interactions with the EDA-NOCV method indicates that the OC→B σ donation is stronger than the B→CO π back donation in both ions.     

Structures,Energetics, and Infrared Spectra of the Cationic Monomethylamine-Water Clusters

The structures, energetics, and infrared (IR) spectra of the cationic monomethylamine-water clusters, [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} (\begin{document}$n$\end{document}=1\begin{document}$-$\end{document}5), have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p) level. The results reveal that the formation of proton-transferred CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O\begin{document}$\cdots$\end{document}HN hydrogen bonds with the positively charged NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} moiety of CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document}, whose motif is retained in the larger clusters. The CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} ion core structure is predicted to be less energetically favorable. Vibrational frequencies of CH stretches, hydrogen-bonded and free NH stretches, and hydrogen-bonded OH stretches in the calculated IR spectra of the CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} and CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} type structures are different from each other, which would afford the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} complexes.     

高聚物的动态红外光谱研究

动态红外光谱法是研究高聚物在外加力场作用下变形或松弛现象的极为有用的手段。本文介绍了动态红外光谱法的实验技术以及若干近期的研究结果。     

草酸钙结石形态的红外光谱分析

草酸钙结石主要是以一水草酸钙(COM)、二水草酸钙(COD)的形式存在。在解决缺少COD标样的难题后,将制备的COD样品与COM标样混合,然后采用红外光谱法对混合物进行分析研究,采用谱带比值法,确定了COD和COM在660和610 cm-1处与780和520 cm-1处的吸收度比值(R)与质量分数(w)的关系式,其线性回归方程分别为:R=11.95×10-3wCOD 0.873 61,r=0.983 63;R=4.74×10-3wCOD 0.886 52,r=0.992 44。同时为了减少压片、测定等因素引起的误差,采用零点交叉一阶导数法,测定在1 320 cm-1处吸收度一阶导数与COD质量分数(w)的关系式,其线性回归方程I=5.5×10-5w 9.2×10-5,r=0.996 60。线性良好。