Resonance Raman effect of the Mo2Cl4−8 ion: A re-examination

The resonance Raman effect of (NH₄)₅Mo₂Cl₉·H₂O was studied at both room and liquid nitrogen temperature. It is shown that the previous explanation, given by other authors, for the appearance of the resonance Raman spectrum excited by 568.2 nm is not a correct one. Based on the Raman and electronic spectra an explanation is suggested for this behavior.     

Raman scattering in nonplanar poly(vinylidene fluoride)

The Raman scattering of nonplanar (form 2) poly(vinylidene fluoride) (PVF₂) is described. Unique Raman bands not observed in the infrared spectra are found at 2973, 1437, 1327, 1198, and 1059 cm^?1. Band assignments are discussed by comparing infrared and Raman spectra of form 2 PVF₂.     

Theoretical Study on Resonance Raman Spectra of Tetraoxaporphyrin Dication by TDDFT Calculation

The B state excited resonance Raman scattering of tetraoxaporphyrin dication (TOP²⁺) was theoretically studied with DFT/TDDFT calculations and the sum-over-states approach of polarizability including both the A and B terms contributions. The resonance Raman spectra calculated with PBE1PBE, B3LYP, Cam-B3LYP, and B3LYP-D3 functionals are similar to each other in general, with PBE1PBE and B3LYP being better in reproducing resonance Raman intensities in comparison with the experiment. The calculated relative intensities of the totally symmetric modes are excellently consistent with the experiment. The TDDFT calculations manifested a considerable deformation of the B state along theυ2,υ6, υ7, and υ8 modes, which is responsible for the strong resonance Raman intensities of these modes. The resonance Raman intensities of non-totally symmetric modes were calculated to be weaker than the totally symmetric modes by one or two order of magnitude, whichqualitatively agrees with the experiment. However, the resonance Raman intensity of the υ10 mode (C_βC_β stretch, B_1g symmetry) predicted by TDDFT calculations is unexpectedly small whereas that of the υ11 mode (symmetric C_αC_m stretch, B_1g symmetry) is too large, which is assumed to be caused by the Jahn-Teller instability for the B state of TOP²⁺.     

Stimulated Raman laser excitation of spontaneous resonance Raman scattering

The efficient conversion of the second and third harmonics of a Nd YAG laser to near UV radiation in the 395–500 nm range by stimulated Stokes (and anti-Stokes) Raman scattering (SRS) in a 1 m Raman oscillator containing compressed H₂ or D₂ is used as an excitation source for spontaneous resonance Raman spectroscopy (RRS). SRS excited RR spectra are shown for the anion radical of tetracyanoquinodimethane (TCNQ).     

Some remarks on the Raman spectra of selected menshutkin complexes

The Raman spectra of the solid complexes naphthalene·2SbCl₃, phenanthrene ·2SbCl₃ and diphenyl ·2SbCl₃ are presented. The differences found in their Raman spectra can be explained by comparing the results with those of NQR and X-ray structure studies given in the literature.     

Correlations between structure and properties of materials. X. Anomalous optical properties and Raman spectra of glassy ternary B2O3–BaTiO3–Na2O materials

The anomalous behavior of refractive index and density in the glassy ternary B₂O₃–BaTiO₃–Na₂O materials is presented and discussed in terms of Raman spectroscopy results. The slope change in the optical properties as a function of composition takes place within the same range of composition in which the Raman spectra suggest a transition from a bridging type of attack on the glassy matrix by the oxygen present in the basic oxide, to a nonbridging type. The structural modifications of the materials at different compositions are inferred from a detailed analysis of the Raman spectra.     

Synthesis and study of hybrid organic-inorganic glycinium fluorozirconates

Hybrid organic-inorganic zirconium fluoride complexes, (GlyH)ZrF₅, (GlyH)ZrF₅ · 2H₂O, and (GlyH)₂ZrF₆, have been synthesized for the first time. They were studied by X-ray powder diffraction and thermal analysis, as well as IR and Raman spectroscopy. The structure of the fluorozirconates was inferred from IR and Raman spectroscopic data.     

Monitoring electrode/electrolyte interfaces of Li-ion batteries under working conditions: A surface-enhanced Raman spectroscopic study on LiCoO2 composite cathodes

Lithium-ion batteries are commonly used for electrical energy storage in portable devices and are promising systems for large-scale energy storage. However, their application is still limited due to electrode degradation and stability issues. To enhance the fundamental understanding of electrode degradation, we report on the Raman spectroscopic characterization of LiCoO₂ cathode materials of working Li-ion batteries. To facilitate the spectroscopic analysis of the solid electrolyte interface (SEI), we apply in situ surface-enhanced Raman spectroscopy under battery working conditions by using Au nanoparticles coated with a thin SiO₂ layer (Au@SiO₂). We observe a surface-enhanced Raman signal of Li₂CO₃ at 1090 cm⁻¹ during electrochemical cycling as an intermediate. Its formation/decomposition highlights the role of Li₂CO₃ as a component of the SEI on LiCoO₂ composite cathodes. Our results demonstrate the potential of Raman spectroscopy to monitor electrode/electrolyte interfaces of lithium-ion batteries under working conditions thus allowing relations between electrochemical performance and structural changes to be established.     

具有表面拉曼增强活性的银纳米材料的合成和表征(英文)

利用简易无模板湿化学法合成了由纳米片组装的具有三维分级结构的银纳米材料。场发射扫描电子显微镜表明柠檬酸氢二铵在这种结构形成过程中起到很重要的作用。X射线衍射和透射电子显微镜表征进一步证明了这种结构的形成。此外本文还对这种分级结构进行了紫外和拉曼表征。这种新型的银纳米结构有望作为一种高灵敏度的表面拉曼增强基底。     

具有表面拉曼增强活性的新型银纳米材料的合成和表征

利用简易无模板湿化学法合成了由纳米片组装的具有三维分级结构的银纳米材料。场发射扫描电子显微镜表明柠檬酸氢二铵在这种结构形成过程中起到很重要的作用。X射线衍射和透射电子显微镜表征进一步证明了这种结构的形成。此外本文还对这种分级结构进行了紫外和拉曼表征。这种新型的银纳米结构有望作为一种高灵敏度的表面拉曼增强基底。     

Raman spectroscopic studies on the structure of materials, specially of glasses, ceramics, films and fibres

A survey is given of applications of Raman spectroscopy in materials characterization. The following topics are covered: Analytical characterization of glasses in the system PbO-B₂O₃ and of glasses and ceramics in the system SrO-B₂O₃-Al₂O₃-TiO₂; investigation and discussion of the so-called Boson peak in the Raman spectra of glasses; Raman spectra obtained with a microscope attachment of carbonaceous materials to study the orientation of graphite planes in films and fibres.     

A vibrational-spectroscopic study of the species present in the CO2−H2O system

Raman and infrared spectra have been recorded of water and heavy-water solutions of carbon dioxide, potassium bicarbonate, and potassium carbonate. The structures of the carbonate and bicarbonate ions and CO₂ (aqueous solution) have been determined from a consideration of Raman and infrared data. The results reveal the presence of solvent effects in the carbonate and CO₂ water solutions. No bands characteristic of H₂CO₃ were observed in the Raman spectrum of aqueous solutions of CO₂.     

In silico modeling of functionalized graphene oxide-metal cluster conjugates as Raman probe: Raman activity of pyridine

Functionalized graphene – metal nano-conjugates are used as Raman probes, in recent years, for trace level identification of materials having specific Raman active modes. In the present paper, model Raman probes were modeled through conjugation of Au₄ and Ag₄ clusters with functionalized graphene systems. In silico models of functionalized (5,5)-graphene sheets were designed at the density functional theory (DFT) level through attachments of epoxy, -OH and –NH(CH₃)₂SH/-CONH(CH₃)₂SH groups. Model Raman probes were designed through attachment of Au₄ and Ag₄ clusters to the functional sites. Full geometry optimizations followed by vibrational analysis were carried out to ensure that the designed Raman probes have acceptable geometric characteristics to attach Raman-active molecules to the metal site. Pyridine was used as a test system to investigate the functionality of such model Raman probes through attachment with the metal clusters. It was observed that the chemical effects due to such attachments increase the Raman intensities (RI) of specific Raman modes of pyridine (in-plane symmetric bending (1040 cm^-1) and asymmetric stretch-bend (1634 cm^-1)), which are too weak in the isolated molecule. Furthermore, the suggested in silico system could provide an important model for basic understanding of RI-enhancements of molecules through increase of the size of the metal clusters, as the observed enhancement was found to be dependent on the polarizability of the metal clusters attached to the molecule of interest.     

A Raman Differential Absorption Lidar for Ozone and Water Vapor Measurement in the Lower Troposphere

Abstract

A new way of measuring ozone and water vapor in the Planetary Boundary Layer (PBL) is proposed. The method is based on the simultaneous measurement of the Raman backscattering in the UV by O₂, N₂ and H₂O, using a single pump beam at 266 nm. The ozone concentration is retrieved from the differential absorption of the N₂ and O₂ Raman backscattered signals, while the water vapor is measured using the classical Raman scheme. We present some preliminary results showing daytime ozone measurements in good correlation with a point monitor.     

Synthesis and vibrational spectroscopic characterisation of synthetic hydrozincite and smithsonite

Hydrozincite and smithsonite were synthesised by controlling the partial pressure of CO₂. Previous crystallographic studies concluded that the structure of hydrozincite was a simple one. However both Raman and infrared spectroscopy show that this conclusion is questionable. Multiple bands are observed in both the Raman and infrared spectra in the (CO₃)²⁻ antisymmetric stretching and bending regions of hydrozincite showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the hydrozincite structure. Multiple OH stretching vibrations centred in both the Raman and infrared spectra show that the OH units in the hydrozincite structure are non-equivalent. The Raman spectrum of synthetic smithsonite is a simple spectrum characteristic of carbonate with Raman bands observed at 1408, 1092 and 730 cm⁻¹.     

V_2O_5/CeO_2催化剂固相反应的Raman光谱研究

采用浸渍法制备了不同V2O5负载量(分别为5%和15%)的V2O5/CeO2催化剂.利用不同激发波长(514和325nm)的Raman光谱,结合X射线衍射(XRD)、紫外-可见漫反射(UV-VisDRS)和N2物理吸附技术,考察了V2O5/CeO2催化剂中V2O5和载体CeO2之间的固相反应.结果表明:催化剂在300℃焙烧时,V2O5与CeO2反应生成CeVO4,升高温度有利于固相反应的发生.样品对325nm光的吸收明显大于对514nm光的吸收,因此325nm激发波长的Raman光谱对催化剂的表层信息更为敏感.当焙烧温度较低时,由于受到表层CeVO4的阻碍,未反应的V2O5残留在载体CeO2孔道或粒子堆积孔道内部,因此514nm激发波长下能观察到V2O5的Raman峰,而表面灵敏的325nm激发波长下观察不到此现象.     

Fragmentation of neutral van der Waals clusters with visible laser light: a new variant of the Raman effect?

We have observed strong photodissociation (using visible laser light) of neutral van der Waals clusters (Ar, N₂, O₂, CO₂, SO₂, NH₃) produced by supersonic expansion and detected by electron ionization/mass spectrometer. Several tests were performed, all of them supporting this surprising discovery. We suggest that Raman induced photodissociation (RIP) is responsible for this phenomenon. This first observation of Raman induced photodissociation provides a new technique for the study of neutral van der Waals clusters.     

Micro-Raman Spectroscopy of Nanostructured Silver Sulfide

Nanostructured silver sulfide powder with an average particle size of about 45 nm, an acanthite α-Ag₂S monoclinic structure (space group P2₁/c), and nonstoichiometric composition Ag_1.93S has been synthesized by the chemical deposition method. The silver sulfide nanopowder has been studied by Raman spectroscopy. According to the Raman scattering data, heating the nanopowder with high-power laser radiation in air leads to photoinduced decomposition of the Ag_1.93S nanopowder to give silver metal. The Raman spectrum of the silver sulfide nanopowder shows a series of bands in the low-frequency range from 90 to 260 cm^–1 associated with vibrations of silver atoms, Ag–S bonds, and symmetric Ag–S–Ag longitudinal modes. Raman spectroscopy confirmed an acanthite monoclinic structure of synthesized silver sulfide nanopowder.     

Ordered ternary compounds of the rare earth sesquisulfides

Intermediate compositions were investigated in eight Ln₂S₃-Ln₂′S₃ systems and reaction products characterized by Raman spectroscopy. Raman spectra are reported for the ordered structures reported in earlier literature. Based on the Raman spectra, LaLuS₃ previously reported as isostructural with LaDyS₃ (the I-type structure) is actually a new ordered compound. It was indexed on an orthorhombic cell with a=7.304, b=6.659 and . A second previously unreported compound, Dy₃ScS₆, was identified by its Raman spectrum. Sharp Raman lines with a unique arrangement for each structure-type indicate that the ternary rare earth sulfides are well-ordered structures.     

NIR FT Raman Spectroscopy–a Rapid Analytical Tool for Detecting the Transformation of Cellulose Polymorphs

This is a report of the combined use of NIR FT Raman spectroscopy and X-ray diffraction measurements (WAXS) to investigate the polymorphic transformation of cellulose I into cellulose II. For this reason samples of cellulose I were swelled in different concentrations of NaOH and dissolved in different molten inorganic salts hydrates (LiCl·2ZnCl₂·6H₂O, LiClO₄·3H₂O, LiSCN·2,5H₂O and ZnCl₂·4H₂O). NIR FT Raman spectra of the alkali treated samples were recorded. They characterize the pure modifications cellulose I and II as well as mixtures of the two polymorphic phases. The results of the Raman measurements were confirmed by X-ray scattering. The paper demonstrates that FT Raman vibrational spectroscopy is a powerful, rapid analytical method which may be used to follow the polymorphic transformation of cellulose I into cellulose II.