熊果酸的Raman光谱和红外光谱结构特征比较

本文采用HRD2型双光栅单色仪测定了熊果酸的Raman光谱，得到熊果酸的特征Raman光谱结构，采用Philips 100型双光栅单色仪测定了熊果酸的IR光谱，得到熊果酸的特征IR光谱结构；解析了熊果酸的Raman光谱和IR光谱与其结构特征的关系，确定了熊果酸的Raman光谱的结构特征和官能团的归属，给出了熊果酸的两个基本骨架特征区域（A区：1386，1370，1363cm^-1，B区：1304，1269，1237cm^-1）；对熊甲酸的Raman光谱和IR光谱作了比较研究，指出Raman光谱具有比IR光谱更为丰富的结构信息的特征，并且，IR光谱的主要特征峰在Raman光谱中均有对应的谱峰；Raman光谱的谱峰形态清晰可变，使熊果酸的主要结构和官能团得到准确的分析和指认，与IR光谱一样，Raman光谱是天然药物解析的有效手段之一。     

A surface-enhanced Raman scattering study of CTAB adsorption on copper

Surface-enhanced Raman spectroscopy (SERS) has been used to study, in situ, the adsorption of cetyltrimethylammonium bromide (CTAB) on copper. The data obtained allow the determination of CTAB's adsorption rate from aqueous solution and are consistent with physisorption or weak chemisorption via the quaternary ammonium group. The use of “surface selection rules” to derive orientation information is examined.     

β-三氯锗基丙酸类化合物的拉曼光谱和红外光谱

我们合成了β-三氯锗基丙酸及其类似物并测量了该化合物的拉曼光谱和红外光谱 ,经光谱分析 ,指认了主要波数所对应的分子振动。在 A、B、C、D四种化合物的拉曼光谱中 ,Ge- Cl的振动分别出现在 397cm- 1( vs)、40 0 cm- 1( vs)、394cm- 1( vs)、385cm- 1( vs)中 ,而在红外光谱中却无法证明 Ge- Cl键的存在 ,Ge- C键的振动在 Raman光谱中分别在 594cm- 1( w)、62 6cm- 1( w)、634cm- 1( w)、641 cm- 1( w)。在红外光谱中 ,各种极性基团的振动表现的更明显 ,分别出现了 O- H、CH2 、C- O和 C=O的振动峰。     

Infrared and Raman spectroscopies of InP/II–VI core-shell nanoparticles

We use infrared (IR) and Raman spectroscopies to investigate the optically active phonon modes in InP nanoparticles and InP/II–VI core-shell nanoparticles fabricated by similar colloidal chemistry methods. The IR transmission spectra of several InP nanoparticle samples exhibit a common absorption feature, which we assign to the Fröhlich mode. The Raman results for the same samples show transverse and longitudinal optical phonon peaks, and scattering strength in between due to surface optical (SO) modes. Infrared spectra of the InP/ZnSe core-shell nanoparticles () exhibit three absorption features, one due to the InP core, and the others associated with the ZnSe shell layer. Raman measurements (12–292 K) also show three phonon-related peaks, whose intensities vary sharply with temperature. The frequencies of the IR and Raman lines are in approximate accord with dielectric continuum theory.     

Raman,FT‐IR,and DFT studies of 3,5‐pyrazoledicarboxylic acid and its Ce(III) and Nd(III) complexes

3,5‐Pyrazoledicarboxylic acid was used as a ligand for the synthesis of its Ce(III) and Nd(III) complexes. The complexes of Ce(III) and Nd(III) with 3,5‐pyrazoledicarboxylic acid were synthesized and their compositions were determined by elemental analysis. Vibrational study in the solid state of 3,5‐pyrazoledicarboxylic acid and its new Ce(III) and Nd(III) complexes was performed by IR and Raman spectroscopy. The changes observed between the IR and Raman spectra of the ligand and of the complexes allowed us to establish the coordination mode of the metal in both complexes. The comparative vibrational analysis of the free ligand and its lanthanide(III) complexes gave evidence that 3,5‐pyrazoledicarboxylic acid binds Ln(III) through the deprotonated carboxylic oxygens. The density functional theory (DFT) calculated geometries, harmonic vibrational modes and Raman scattering activities of the ligand were in good agreement with the experimental data, and a complete vibrational assignment is being proposed. The experimental IR and Raman bands of the ligand were assigned to normal modes on the basis of DFT calculations. The effect of the intramolecular hydrogen bonds in the ligand on vibrational mode positions is also discussed. The characteristic IR and Raman bands of 3,5‐pyrazoledicarboxylic acid and its lanthanide complexes were specified and discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

Theoretical studies of molecules adsorbed on solid surfaces: I. Electronic spectra

The band shape of electronic spectra for a diatomic molecule adsorbed on a surface is studied using the adiabatic approximation. In this approximation, the Schrödinger equation for the total system is separated into those for electronic motion, intramolecular vibration, and low frequency motions (e.g., hindered molecular rotation and lattice vibration). Our theory is applied to the system of an admolecule on the (001) surface of fcc monatomic crystals. We determine the line shape of a vibronic transition for both chemisorption and physisorption cases. In chemisorption cases, a side band due to the low frequency motions can appear in the line shape of a vibronic transition. On the other hand, in physisorption cases, the line shape is a single peak. Moreover, we suggest theoretically a new experimental technique for exciting adsorbed molecules; for this purpose, we derive equations giving the cross sections for the electronic excitation of admolecules by using ion impact at grazing incidence. The admolecules can be excited by this method; the subsequent light emission can give information on the orientation of the admolecule on the surface and on the admolecule-surface species interaction.     

Adsorption studies of trichloroethylene (TCE) on MgO(100)/Mo(100)

Employing ultraviolet photoelectron spectroscopy (UPS, He I), the more surface sensitive metastable impact electron spectroscopy (MIES) and temperature programmed desorption (TPD) measurements of the adsorption properties of the pollutant trichloroethylene (TCE) on thin MgO(100) films, grown on a Mo(100) single crystal, have been investigated. From TPD spectra of different coverages it is concluded that TCE interacts only weakly with MgO, which is attributed to physisorption. For increasing coverages a change from one peak to two peaks in the TPD spectra, one at higher, the second at lower temperatures with respect to the single peak is detected. Additionally, the observation of a local minimum for the work function (WF) for both MIES and UPS spectra is presented. Such a local minimum has been reported previously for the adsorption of metals with outer s valence electrons on transition metal substrates and adsorption of metals with outer s valence electrons on metal oxide films. Herein, we present the first WF minimum observed for a system of organic molecules adsorbed on an insulating surface. Two different models are discussed in order to understand the presented results.     

β-三苯锗基丙酸及β-三苯锗基丁酸的拉曼及红外光谱

我们合成了有机锗化合物的一类重要中间体β-三苯锗基丙酸和β-三苯锗基丁酸 ,测量了该化合物的拉曼光谱和红外光谱 ,经光谱分析 ,指认了主要波数所对应的分子振动。在这两种化合物的拉曼光谱中 ,30 50 cm- 1( m)、1 0 2 5cm- 1( m)和 61 8cm- 1( m)分属于 Ph- H的伸缩振动、面内弯曲振动和面外扭曲振动。饱和 Ge- C键的振动分别在 594cm- 1和 587cm- 1,同时指出了 Ph- Ge的几种振动所对应的振动频率。在红外光谱中 ,C=O的振动出现在 1 70 9cm- 1( s)和 1 70 5cm- 1( s) ,与饱和碳相连接的 Ge- C振动出现在 61 7cm- 1( w)和 61 7cm- 1( w)。     

[MnHg(SCN)4(H2O)2]·2C4H9NO(MMTWD)晶体的光谱分析

根据商群对称性分析法对MMTWD晶体的振动模作了理论计算.计算结果显示,通过实验可观察到的拉曼散射峰和红外反射带应分别不超过297和148个.运用实验的手段,分别测定晶体的拉曼光谱和红外光谱,给出了MMTWD晶体在50～3 000 cm-1范围内的拉曼光谱图和400～4 000 cm-1范围里的红外光谱图,并对光谱中的谱线作了指认.给出了MMTWD晶体的分子结构示意图,最终确定MMTWD晶体结构为三维网状结构,说明在众多新型光功能材料当中MMTWD晶体是一种更适合生长成较大尺寸且稳定性较好的非线性光学晶体,在光电子领域中具有良好的应用前景.     

Silicon nanoparticles: Their photoluminescence, complex refractive index, and relationship with the band structure

The photoluminescence, IR transmission, and Raman scattering spectra of nc-Si nanocrystals (5 nm in size) have been investigated. The shape and spectral position of maxima in the photoluminescence and IR transmission spectra are theoretically described. It is shown that nc-Si particles consist of a Si core and a SiO₂ shell. The existence of surface Si-O and Si-H states in Si nanocrystals enhances photoluminescence. It is established that the spectral position of the main Raman scattering peak in the frequency range 500–520 cm^?1 undergoes a significant red shift for small-size nanostructures. Based on direct determination of the complex refractive index of n-Si nanoparticles by measuring spectral ellipsometric parameters, nanostructured silicon is found to be an indirect-gap semiconductor.     

表面增强拉曼光谱研究胞嘧啶在银胶上的吸附行为

为探讨胞嘧啶(Cytosine,Cy)在基底银表面的吸附特性和规律,采用表面增强拉曼散射(SERS)光谱对其吸附行为进行分析,并结合量子化学密度泛函理论(DFT)/B3LYP计算方法对Cy分子的常规拉曼光谱(NRS)及Cy与Ag团簇吸附的SERS光谱进行计算,与测定结果进行比对且对其拉曼峰进行系统指认及归属,理论计算结合实测值探讨了Cy在基底Ag上的增强效应和吸附行为。考察了Cy分子在Ag纳米粒子上的不同吸附时间、浓度、pH等条件对SERS光谱的影响及优化,发现pH影响最大,在中性和强碱性条件下的增强效应明显优于酸性。Cy分子存在2种不同的异构体和3种不同的存在形态,并随酸度变化相互转化而达动态平衡。基于Cy在不同pH时的形态分布和相应的SERS变化规律,结合DFT算得的Cy分子中的电荷分布及在银基底表面的吸附机制,详细探讨了酸碱对Cy分子的SRES光谱影响的内因和吸附机理,指出在中性和弱碱性时,是Cy中的N3和O与Ag形成配位吸附;在pH大于11时,N与Ag形成配位吸附,而O与Ag形成共价吸附。     

A study of water vapour adsorption on the (110) surface of copper

The adsorption of water vapour on the (110)Cu face has been studied by AES and Δφ measurements in the 5 × 10^?9 to 3 × 10^?7 Torr range between 75 and 500°C. At lower temperatures, an initial physisorption of oriented water dipoles produces a fast initial Δφ decrease. Further adsorption causes no important changes of the Cu surface potential. At higher temperatures (above 100°C) a partial dissociation of the water molecules leads to a dissociative chemisorption producing a Δφ increase after the initial Δφ decrease due to water physisorption.     

Electron loss spectroscopy of clean and oxygen covered GaAs(110) surfaces

Electron energy loss spectra of clean and oxygen covered GaAs(110) surfaces have been measured with a four grid retarding field analyser. Loss spectra of clean cleaved p- and n-type surfaces are slightly different and different states of adsorption for the oxygen on the two surfaces are found. The loss peaks which are common in the spectra obtained from clean surfaces of both types of material have been interpreted in terms of bulk and surface excitations. The data associated with the bulk excitations are in good agreement with previous optical and electron transmission data while loss peaks at 11.5 and 18.5 eV are interpreted as the surface plasma loss and a surface state transition respectively. For n-type material extra loss peaks were observed. In the case of oxygen adsorption on these surfaces new loss peaks were found at 13.5, 17.2 and 28.1 eV in both spectra and are assumed to be characteristic of the oxygen. Further, for n-type material an extra peak occurs at 8.2 eV.     

莽草酸FTIR，FT-Raman光谱及SERS研究

报道了莽草酸的FTIR,固态及饱和液态的FT-Raman光谱, 归属并分析了莽草酸分子内各基团的振动峰位及其相应基团在两种振动光谱中的振动峰位变化规律。利用表面增强拉曼散射(SERS)光谱及表面吸附选择定律研究了莽草酸在以银粒子为活性基底表面的吸附状态及其不同浓度变化对其SERS的影响,探讨了莽草酸在银粒子表面的吸附机理和规律。实验结果表明,红外与拉曼光谱结合较为全面地解析了莽草酸的分子结构中各基团的振动情况;获得了莽草酸在银粒子表面的最佳SERS效应的浓度范围, 莽草酸浓度小于1×10-3 mol·L-1时, 其SERS明显趋好;根据SERS作用机制,莽草酸的分子在银粒子表面的吸附主要是通过其羟基、羧基的电荷转移机制及其亚甲基、次甲基的电磁作用机制共同作用;其环内双键没有明显SERS表明其未能在银粒子表面产生有效吸附理。     

银杏内酯分子结构和光谱性质的理论研究

采用密度泛函理论方法详细考察四种银杏内酯分子(银杏内酯A、B、C和J)的结构和光谱性质.研究发现，改变银杏内酯上的取代基，银杏内酯分子骨架具有相对稳定的结构.基于优化得到的稳定结构，我们计算得到了四种银杏内酯分子的红外(Infrared,IR)光谱、拉曼(Raman)光谱和振动圆二色(Vibrational circular dichroism,VCD)光谱性质.我们发现，四种银杏内酯分子的IR光谱图在1100 cm-1有较明显的区别，这些振动峰主要是银杏内酯分子中C-O-C键的伸缩振动峰.在Raman光谱图中，波长在3600cm-1处为银杏内酯分子中羟基的伸缩振动，银杏内酯A、银杏内酯B、银杏内酯C分裂成了两个强度不等的振动峰，而银杏内酯J分子表现为一个宽的振动峰.在VCD光谱图中，我们发现四种银杏内酯分子在3800 cm-1附近有明显的区别.     

Electron spectroscopy applied to the study of reactivity at metal surfaces — A review

Photoelectron spectroscopy (PES) has become an important tool in the study of surfaces and the solid state. This review discusses information obtained on the interaction of gases with metal surfaces. The fundamentals of electron spectroscopy are briefly reviewed and experimental methods outlined. Approaches to the interpretation of both X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectra (UPS) are discussed. The chemisorption of carbon monoxide is examined in detail, PES distinguishes two situations, where CO retains its molecular identity and where dissociation occurs. Bonding of the molecule is considered, as are factors affecting dissociation. Some XPS investigations of metal oxidation are examined and the significance of the several oxygen 1s peaks observed is discussed. The adsorption and decomposition of organic molecules has been studied primarily by UPS. Several investigations are summarized, and the decomposition of formic acid considered in detail. The application of electron excited Auger electron spectroscopy is briefly discussed.     

Chemical modification of the surface of Fe<Subscript>75</Subscript>Si<Subscript>25</Subscript> alloy particles with stearic acid under high-energy ball-milling conditions

The morphology, phase composition and surface structure of Fe₇₅Si₂₅-alloy particles are studied by electron microscopy, X-ray diffraction analysis, and Mössbauer, Auger, IR (infrared) and X-ray photoelectron spectroscopy. The alloy particles used as fillers for the polyethylene matrix are produced by high-energy ball milling in an organic medium with the addition of stearic acid. The addition of stearic acid is shown to promote plasticization of the brittle Fe₇₅Si₂₅ alloy and the formation of a surface layer of no more than 1.5 nm thick, consisting of oxides based on iron and silicon, responsible for the chemisorption of stearic acid on the surface. Chemical modification of the surface of filler particles with an amphiphilic surfactant is carried out to enhance their adhesion in the polymer matrix.     

Vibrational spectroscopic studies of the structure of di‐amino acid peptides. Part II: cyclo(L‐Asp‐L‐Asp) in the solid state and in aqueous solution

Solid‐state protonated and N,O‐deuterated Fourier transform infrared (IR) and Raman scattering spectra together with the protonated and deuterated Raman spectra in aqueous solution of the cyclic di‐amino acid peptide cyclo(L ‐Asp‐L ‐Asp) are reported. Vibrational band assignments have been made on the basis of comparisons with previously cited literature values for diketopiperazine (DKP) derivatives and normal coordinate analyses for both the protonated and deuterated species based upon DFT calculations at the B3‐LYP/cc‐pVDZ level of the isolated molecule in the gas phase. The calculated minimum energy structure for cyclo(L ‐Asp‐L ‐Asp), assuming C₂ symmetry, predicts a boat conformation for the DKP ring with both the two L ‐aspartyl side chains being folded slightly above the ring. The CO stretching vibrations have been assigned for the side‐chain carboxylic acid group (e.g. at 1693 and 1670 cm⁻¹ in the Raman spectrum) and the cis amide I bands (e.g. at 1660 cm⁻¹ in the Raman spectrum). The presence of two bands for the carboxylic acid CO stretching modes in the solid‐state Raman spectrum can be accounted for by factor group splitting of the two nonequivalent molecules in a crystallographic unit cell. The cis amide II band is observed at 1489 cm⁻¹ in the solid‐state Raman spectrum, which is in agreement with results for cyclic di‐amino acid peptide molecules examined previously in the solid state, where the DKP ring adopts a boat conformation. Additionally, it also appears that as the molecular mass of the substituent on the C^α atom is increased, the amide II band wavenumber decreases to below 1500 cm⁻¹; this may be a consequence of increased strain on the DKP ring. The cis amide II Raman band is characterized by its relatively small deuterium shift (29 cm⁻¹), which indicates that this band has a smaller N H bending contribution than the trans amide II vibrational band observed for linear peptides. Copyright © 2009 John Wiley & Sons, Ltd.     

Assignments of Carbon-Sulphur Vibrations by Selenation: An FT-IR and FT-Raman Study on 1, 3, 5-Trithiacyclohexane

Abstract

The IR and Raman spectra of 1, 3, 5-trithiacyclohexane (1) and 1, 3, 5-triselenocyclohexane (2) have been recorded with FT-instrumentation within 3500–100 cm^?l, and the C-S vibrations of 1 have been reviewed by comparing its spectra with those of 2. The IR and Raman spectra slightly differ from those previously reported and some vibrations, previously assigned to C-H modes in 1on the basis of NCT calculations, are reassigned to C-S modes on the basis of the selenation effect. “Selenation” has proved to be a very simple and effective tool in recognizing carbon-sulfur vibrations both in IR and Raman. The Raman peaks due to carbon-chalcogen vibrations are less intense in 1 than in 2, according to the higher polarizability of the selenium atom.