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Raman Spectroscopy (raman + spectroscopy)
Kinds of Raman Spectroscopy Selected AbstractsIDENTIFICATION AND DIFFERENTIATION OF OPAQUE CHINESE OVERGLAZE YELLOW ENAMELS BY RAMAN SPECTROSCOPY AND SUPPORTING TECHNIQUES*ARCHAEOMETRY, Issue 1 2010J. MIAO Using Raman spectroscopy, energy-dispersive X-ray fluorescence and X-ray diffraction, the Pb,Sn,Sb triple oxide yellow and lead,tin yellow have been identified on two pieces of cloisonné enamel (Falangcai) porcelains. Lead,tin yellow and lead antimonate yellow have been identified on famille rose porcelains manufactured before and after 1911, respectively. The replacement of the Pb,Sn,Sb triple oxide yellow by lead,tin yellow and that of the lead,tin yellow by lead antimonate yellow are discussed. [source] Preparation and characterization of electrodeposited indium selenide thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2005S. Gopal Abstract Indium Selenide (InSe) thin films were deposited from a mixture of Indium chloride and selenium dioxide in aqueous solution by electrodeposition technique on Indium Tin oxide coated glass substrates. The effects of the parameters during deposition such as current density, deposition potential versus saturated calomel electrode, pH value and concentration of source material were studied. X-ray diffraction studies were carried out on the films to analyze the microstructure using an x-ray diffractometer and were examined by RAMAN spectroscopy. The Raman peak position did not change much with chemical concentrations. Raman scattering due to the (LO) phonon was observed at 211 cm,1. Optical absorption studies were performed with a double beam ultra violet-visible ,NIR spectrophotometer in the wavelength 300,1100 nm. The surface morphology of the layer was examined using a scanning electron micrograph. The composition of the films was studied using an Energy Dispersive Analysis by X-Rays (EDAX). [source] Mechanistic Study of Partial Oxidation of Methane to Syngas Using In Situ Time-Resolved FTIR and Microprobe Raman SpectroscopiesTHE CHEMICAL RECORD, Issue 2 2002Mechanism of Methane Partial Oxidation Abstract In situ time-resolved Fourier transform infrared (FTIR) and microprobe Raman spectroscopies were used to characterize the reaction mechanisms of the partial oxidation of methane to syngas over SiO2 - and ,-Al2O3 -supported rhodium and ruthenium catalysts. The interaction of both pure methane and a methane/oxygen mixture at a stoichiometric feed ratio with an oxygen-rich catalyst surface led to the formation of CO2 and H2O as the primary products. For the H2 -pretreated samples, the reaction mechanisms with the catalysts differ. Only Rh/SiO2 is capable of catalyzing the direct oxidation of methane to syngas, while syngas formation over Rh/g-Al2O3, Ru/SiO2, and Ru/g-Al2O3 can be achieved mainly via a combustion-reforming scheme. The significant difference in the mechanisms for partial oxidation of methane to syngas over the catalysts can be correlated to the differences in the concentration of oxygen species (O2,) on the catalyst surface during the reaction, mainly due to the difference in the nature of the metals and supports. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2:102,112, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10016 [source] Fabrication and Properties of Conducting Polypyrrole/SWNT-PABS Composite Films and NanotubesELECTROANALYSIS, Issue 11 2006Abstract We report the electropolymerization and characterization of polypyrrole films doped with poly(m-aminobenzene sulfonic acid (PABS) functionalized single-walled nanotubes (SWNT) (PPy/SWNT-PABS). The negatively charged water-soluble SWNT-PABS served as anionic dopant during the electropolymerization to synthesize PPy/SWNT-PABS composite films. The synthetic, morphological and electrical properties of PPy/SWNT-PABS films and chloride doped polypyrrole (PPy/Cl) films were compared. Characterization was performed by cyclic voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. SEM and AFM images revealed that the incorporation of SWNT-PABS significantly altered the morphology of the PPy. Cyclic voltammetry showed improved electrochemical properties of PPy/SWNT-PABS films as compared to PPy/Cl films. Raman Spectroscopy confirmed the presence of SWNT-PABS within composite films. Field effect transistor (FET) and electrical characterization studies show that the incorporation of the SWNT-PABS increased the electronic performance of PPy/SWNT-PABS films when compared to PPy/Cl films. Finally, we fabricated PPy/SWNT-PABS nanotubes which may lead to potential applications to sensors and other electronic devices. [source] Large-Area Silver-Coated Silicon Nanowire Arrays for Molecular Sensing Using Surface-Enhanced Raman Spectroscopy,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2008Baohua Zhang Abstract A new and facile method to prepare large-area silver-coated silicon nanowire arrays for surface-enhanced Raman spectroscopy (SERS)-based sensing is introduced. High-quality silicon nanowire arrays are prepared by a chemical etching method and used as a template for the generation of SERS-active silver-coated silicon nanowire arrays. The morphologies of the silicon nanowire arrays and the type of silver-plating solution are two key factors determining the magnitude of SERS signal enhancement and the sensitivity of detection; they are investigated in detail for the purpose of optimization. The optimized silver-coated silicon nanowire arrays exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability, and reproducibility. Their further applications in rapidly detecting molecules relating to human health and safety are discussed. A 10 s data acquisition time is capable of achieving a limit of detection of approximately 4,×,10,6M calcium dipicolinate (CaDPA), a biomarker for anthrax. This value is 1/15 the infectious dose of spores (6,×,10,5,M required), revealing that the optimized silver-coated silicon nanowire arrays as SERS-based ultrasensitive sensors are extremely suitable for detecting Bacillus anthracis spores. [source] Oligophenylenevinylenes in Spatially Confined Nanochannels: Monitoring Intermolecular Interactions by UV/Vis and Raman Spectroscopy,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2008Mariya Aloshyna Abstract Perhydrotriphenylene-based channel-forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)-type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host-guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials for opto-electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi-isolated entities of tightly packed, well-oriented objects with high PL quantum yields and the possibility of color tuning. [source] Study of Cation Ordering in Ba(Yb1/2Ta1/2)O3 by X-Ray Diffraction and Raman SpectroscopyINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2008Dibyaranjan Rout The complex perovskite Ba(Yb1/2Ta1/2)O3 has been prepared by the two-stage solid-state reaction method. Rietveld' refinement analysis indicates cubic perovskite phase with space group . The 1:1 cation ordering at the B-site is revealed by the presence of (111) superlattice reflection in the X-ray diffraction pattern and further evidenced by the presence of A1g and F2g vibrational modes in the Raman spectra. The dielectric constant is measured to be 29.1, the product of quality factor and resonant frequency (Q×f) is found to be 32,000 GHz and the temperature coefficient of resonant frequency (,f) is 135 (ppm/°C) in the temperature range 30,70°C. [source] Quick Screening of Crystal Methamphetamine/Methyl Sulfone Exhibits by Raman SpectroscopyJOURNAL OF FORENSIC SCIENCES, Issue 4 2010Robert G. Weston M.Sc. Abstract:, The analysis of mixtures of "crystal meth" (usually comprised of methyl sulfone [MS] and methamphetamine [MA]) by gas chromatography-mass spectrometry (GCMS) is routine in many forensic drug laboratories. The utilization of Raman spectroscopy for the identification of such mixtures quickly and without the need for a separation technique is discussed. Samples were dissolved in water and Raman spectra of the resulting aqueous solutions were collected. By comparing these spectra to spectra of methylsulfone and MA mixtures of known composition, an indication of the composition of the sample can be obtained in only a few minutes. This spectral comparison also can be used as a semi-quantitative analysis of MA concentrations in such exhibits. [source] Screening Tablets for DOB Using Surface-Enhanced Raman Spectroscopy,JOURNAL OF FORENSIC SCIENCES, Issue 5 2007Steven E. J. Bell Ph.D. Abstract:, 2,5,-Dimethoxy-4-bromoamphetamine (DOB) is of particular interest among the various "ecstasy" variants because there is an unusually long delay between consumption and effect, which dramatically increases the danger of accidental overdose in users. Screening for DOB in tablets is problematic because it is pharmacologically active at 0.2,3 mg, which is c. 50 times less than 3,4-methylenedioxy-N-methylamphetamine (MDMA) and makes it more difficult to detect in seized tablets using conventional spot tests. The normal Raman spectra of seized DOB tablets are dominated by the bands of the excipient with no evidence of the drug component. Here we report the first use of on-tablet surface-enhanced Raman spectroscopy (SERS) to enhance the signal from a low concentration drug. Raman studies (785-nm excitation) were carried on series of model DOB/lactose tablets (total mass c. 400 mg) containing between 1 mg and 15 ,g of DOB and on seized DOB tablets. To generate surface-enhanced spectra, 5 ,L of centrifuged silver colloid was dispensed onto the upper surface of the tablets, followed by 5 ,L of 1.0 mol/dm3 NaCl. The probe laser was directed onto the treated area and spectra accumulated for c. 20 sec (10 sec × 2). It was found that the enhancement of the DOB component in the model tablets containing 1 mg DOB/tablet and in the seized tablets tested was so large that their spectra were completely dominated by the vibrational bands of DOB with little or no contribution from the unenhanced lactose excipient. Indeed, the most intense DOB band was visible even in tablets containing just 15 ,g of the drug. On-tablet surface-enhanced Raman spectroscopy is a simple method to distinguish between low dose DOB tablets and those with no active constituent. The fact that unique spectra are obtained allows identification of the drug while the lack of sample preparation and short signal accumulation times mean that the entire test can be carried out in <1 min. [source] Tip-Enhanced Raman SpectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2009V. Deckert Abstract This special issue of the Journal of Raman Spectroscopy deals with the advances of Tip-Enhanced Raman Spectroscopy (TERS) since its experimental verification about 10 years ago. The contributed papers reflect a snapshot of current research related to experimental, theoretical and, last but not least, application-oriented advances in this field. The contributions highlight the fact that TERS is a very active field of research and, while the rewards with respect to lateral resolution and detection limits are intriguing, great care is necessary to avoid the pitfalls related either to the experimental design or to the interpretation of data. This special issue intends to provide the basis for a further step towards a standardised approach to TERS. Copyright © 2009 John Wiley & Sons, Ltd. [source] Recent advances in linear and nonlinear Raman spectroscopy II,JOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2008W. Kiefer Abstract Following the first review on recent advances in linear and nonlinear Raman spectroscopy, the present review summarizes papers mainly published in the Journal of Raman Spectroscopy during 2007. This serves to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopy in art and archaeologyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2008Pietro Baraldi Abstract This paper introduces presentations given at the fourth International Conference on the Application of Raman Spectroscopy in Art and Archaeology, held in Modena, Italy, in the Ducal Palace, on 5,8 September 2007. The subjects of lectures and posters presented were concerned mainly with the new applications of Raman microscopy and other Raman techniques to more problematic samples, such as lakes, inks, and fluorescent dyes. Chronologically, the applications extended from the 10th century BC to the present day. The areas considered in the research were wide-ranging in terms of subject-matter and also geographically. New techniques have been developed for the study of binders in paintings and lakes, and with movable instrumentation on unmovable samples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopy and related techniques: state of the art and future directions in Italy,JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008Giuseppe Compagnini Abstract The 20th Italian Conference on Raman Spectroscopy and non-linear effects was held in Catania in June 2007. I had the pleasure to chair the Conference in which scientists from different countries shared their research activities, started new collaborations and straightened the existing ones. For the first time in the GNSR history, the contributors were invited to present papers suitable to be collected in a Special Issue of a peer-reviewed journal and the Journal of Raman Spectroscopy has been chosen for its long tradition on Raman spectroscopy and related fields. This Special Issue is dedicated to the memory of Giorgio Mattei who recently passed away. It includes 28 contributions reporting results and new ideas on material science, biochemistry, astrophysics and science of cultural heritage. Copyright © 2008 John Wiley & Sons, Ltd. [source] Recent Advances in linear and nonlinear Raman spectroscopy IJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2007W. Kiefer Abstract Raman spectroscopy has advanced considerably in the last several years due to rapid developments in instrumentation and the availability of theoretical methods for accurate calculation of Raman spectra, thus enormously facilitating the interpretation of Raman data. This review is restricted to cover papers mainly published in the Journal of Raman Spectroscopy, which serve to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2007 John Wiley & Sons, Ltd. [source] Raman spectroscopy in art and archaeologyJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Ludovic Bellot-Gurlet Abstract This paper gives a short overview of the Special Issue on Raman Spectroscopy in Art and Archaeology, with the papers collected after the ,3rd International Conference on the Application of Raman Spectroscopy in Art and Archaeology' held at the University Pierre et Marie Curie-Paris 6, Paris, France, from 31 August to 3 September, 2005. The contributions present an extended view of the work in the field, from technical developments and special analytical procedures to various applications. Copyright © 2006 John Wiley & Sons, Ltd. [source] Raman spectroscopy at the beginning of the twenty-first centuryJOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006M. Schmitt Abstract This paper gives a summary of the Wolfgang Kiefer Honorary Issue of the Journal of Raman Spectroscopy. The contributions in this special issue convincingly demonstrate the great applicability of Raman spectroscopy for almost all natural sciences, making this technique one of the most essential laser spectroscopic methods. Copyright © 2006 John Wiley & Sons, Ltd. [source] Raman spectroscopy in art and archaeologyJOURNAL OF RAMAN SPECTROSCOPY, Issue 8-9 2004P. Vandenabeele Abstract Raman spectroscopy is becoming increasingly important as an analytical and diagnostic tool for the investigation of precious and brittle objects of art and antiquities. In addition to this introductory paper, this special issue of the Journal of Raman Spectroscopy contains 31 papers dedicated to this subject. This introduction gives an overview and paints a picture of the different approaches in this field. Copyright © 2004 John Wiley & Sons, Ltd. [source] Raman Spectroscopy of Ferroelectric Thin Films and SuperlatticesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Dmitri A. Tenne Recent results of Raman spectroscopy studies of lattice dynamics and phase transitions in ferroelectric thin films and superlattices are reviewed. Raman studies of SrTiO3, BaTiO3, and BaxSr1,xTiO3 thin films in comparison with corresponding single crystals are presented; essential differences in the lattice dynamics behavior of thin films and single crystals are discussed. Application of ultraviolet Raman spectroscopy for studies of nanoscale ferroelectric heterostructures, such as BaTiO3/SrTiO3 superlattices, is demonstrated. [source] Nonlinear optical microscopy of cellular structuresLASER PHYSICS LETTERS, Issue 1 2004G.I. Petrov Abstract We propose a novel nonlinear optical spectroscopic technique H-CARS (Hyper Coherent Anti-Stokes Raman Spectroscopy) to allow imaging of biological structures in real time. Schematic diagram illustrating spectroscopic imaging of cellular membranes using H-CARS microscopy (© 2004 by HMS Consultants. Inc. Published exclusively by WILEY-VCH Verlag GmbH & Co.KGaA) [source] Automated Raman Spectroscopy as a Tool for the High-Throughput Characterization of Molecular Structure and Mechanical Properties of PolyethylenesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2003Claus Gabriel Abstract Raman spectroscopy, which does not require a time-consuming sample preparation, is described as an analytical tool for the high-throughput characterization of polyethylenes. The content of comonomer and the amount of methyl groups per 1,000 carbon atoms of polyethylenes can be predicted from Raman spectra using multivariate data analysis. In addition, macroscopic properties, such as density and elastic modulus as well as yield stress, can be derived from Raman spectra. Raman spectra of selected metallocene-catalyzed polyethylenes of different comonomer content. [source] Synthesis of dendrimer,carbon nanotube conjugatesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008A. García Abstract We describe the coupling between Carbon Nanotubes (CNTs) and a second-generation cyanophenyl-based dendrimer. The goal of our work is the synthesis of highly functionalized CNTs without provoking damage to the conjugated ,-system. One approach is the attachment of dendrimers with a high density of functional groups to the CNTs. These groups serve as anchor points for further reactions. With this aim, we have carried out a primary modification on CNTs by the use of 1,3 dipolar cycloaddition reaction. We have employed Single Wall Carbon Nanotubes (SWNTs) as well as Multi Wall Carbon Nanotubes (MWNTs) obtaining 238 ,mol and 511 ,mol of pyrrolidine groups per gram, respectively. The amount of amino groups introduced in the system was measured by the Kaiser test as well as thermogravimetric analyses. As a second step, dendrimer incorporation was performed by carbodiimide chemistry. Thermogravimetric Analysis, Raman Spectroscopy and Atomic Force Microscopy characterization techniques are reported for the characterization of the final CNT,dendrimer conjugate. The results show that the dendrimer has been attached covalently to the previously generated amine groups. Morphologically, the attached dendrimer with an estimated theoretical molecular length of 6.4 nm, generates a wrapping of 8 nm thick around the CNTs walls. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mechanical and tribological characterization of CNx films deposited by d.c. magnetron sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007L. Ipaz Abstract Carbon nitride (CNx) thin films were deposited onto silicon and steel substrates at 400 °C from a carbon target by d.c. magnetron sputtering system. The composition, structural, and mechanical properties of deposited films were investigated as a function of argon/nitrogen concentration and sputtering power, by means of Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RS), and nanoindentation. The EDS and Elastic Forward Analisys Analysis (EFA) showed that the nitrogen concentration in the CNx deposited films varied between 16% and 28% at depending on nitrogen concentrations in argon/nitrogen gas mixture, and deposition power. FTIR analysis indicated the presence of 2266 and 2278 cm,1 stretching peaks associated with CN triple bonds of nitriles and isocyanides, 1640 cm,1 and 1545 cm,1 associated with the C=C and C=N bonds. The thickness of the CNx deposited films varied between 0.4 and 0.8 µm at different sputtering powers. The hardness and Young's modulus were investigated by depth sensing nanoindentation method. The obtained hardness and Young's modulus increased from 4 to 17 GPa, and from 50 to 170 GPa, respectively; when the nitrogen content in the deposited films diminished between 28 and 12%. On the other hand, the friction and wear tests were done using a pin-on-disc tribometer. The friction tests showed values of 0.05 and 0.4 in dry air and humid atmosphere; respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Raman Spectroscopy of Laser-Shocked NitrobenzenePROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2002Naoshi Kozu A technique for in situ Raman spectroscopy of laser-shocked nitrobenzene was developed. Raman spectra of shocked nitrobenzene are obtained up to ,3.5,GPa, and peak shifts at particular frequencies are observed. The shifts are plotted as a function of density and compared with the data under isothermal compression. Both data provide the same results. This indicates that the numbers of peak shifts of nitrobenzene depend solely on material density. [source] Tracking Flavin Conformations in Protein Crystal Structures with Raman Spectroscopy and QM/MM Calculations,ANGEWANDTE CHEMIE, Issue 13 2010Kjendseth Røhr, Åsmund Strahlenschäden: Für eine aussagekräftige Analyse von Flavoenzym-Kristallstrukturen muss die Cofaktorkonformation genau bekannt sein. Doch durch Röntgenstrahlen während der Datensammlung erzeugte Photoelektronen können den Flavincofaktor reduzieren und so seine Geometrie ändern (siehe Bild). Parallel zur Datensammlung beobachtete Raman-Schwingungsmoden lieferten wichtige Informationen über den tatsächlichen Flavinzustand. [source] Determining Pressure with Daughter Minerals in Fluid Inclusion by Raman Spectroscopy: Sphalerite as an ExampleACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009Yuping YANG Abstract: Raman frequency of some materials, including minerals, molecules and ions, shifts systematically with changing pressure and temperature. This property is often used as a pressure gauge in high pressure experiments with the hydrothermal diamond anvil cell (HDAC). Since the system of fluid inclusion is similar to that of HDAC, it can also be used to determine the internal pressure of fluid inclusions. Sphalerite is a common daughter mineral. In this study, the frequency shift of the 350 cm,1 peak of sphalerite has been studied from 296 to 523 K and from 0.07 to 2.00 GPa using the HDAC. The global slope of the isotherms (,V350/,p)T is 0.0048 in the studied pressure range. No significant variation of the slopes with temperature has been observed. The correlation between the frequency shift of the 350 cm,1 peak of sphalerite and pressure and temperature is constrained as P=208.33(,Vp)350+3.13T,943.75. This relationship may be used to estimate the internal pressure of the sphalerite-bearing fluid inclusions. [source] NaNO2 + NaNO3 Phase Diagram: New Data from DSC and Raman Spectroscopy.CHEMINFORM, Issue 15 2006Rolf W. Berg Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Raman Spectroscopy of Rhombohedral P4O10.CHEMINFORM, Issue 31 2003Sean J. Gilliam Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: In situ Characterization of Phase Transitions in Cristobalite under high Pressure by Raman Spectroscopy and X-Ray Diffraction.CHEMINFORM, Issue 47 2001V. B. Prokopenko Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Tuning of Electronic Properties in Thienyl-Phosphole ,-Conjugated Systems through P-Functionalization Monitored by Raman SpectroscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2006Juan Casado Dr. Abstract Herein, a Raman spectroscopic study of a new family of 2,5-di(2-thienyl)phospholes and thienyl-capped 1,1,-diphospholes is presented. The Raman spectra have been carefully assigned with the help of density functional calculations. For di(2-thienyl)phospholes, two well-differentiated groups of Raman bands exist that arise either from the central phosphole ring or from the outer thiophene substituents. These data reveal a segmentation of the electronic structure. This paper reports interesting relationships between geometrical data such as the BLA (bond-length alternation) parameter and Raman band wavenumbers. These correlations are unprecedented in the chemistry of phospholes and have been used to interpret the evolution of the electronic structure (aromaticity,,-conjugation) upon 1) substitution of the central sulfur atom of terthiophene by phosphorus and 2) P-functionalization. Increasing the coordination number of the phosphole ring results in intramolecular charge transfer. The best scenario for phosphole aromaticity is found for 1,1,-diphospholes. [source] Selectively Deposited Silver Coatings on Gold-Capped Silicon Nanowires for Surface-Enhanced Raman SpectroscopyCHEMPHYSCHEM, Issue 8 2009M. Becker Dr. Abstract Gold caps on silicon nanowires are selectively coated with silver by autometallography (electroless deposition). Changing the conditions of silver deposition, a variety of different coating morphologies can be produced (see figure). The different silver coating morphologies are investigated in terms of their capabilities for surface enhanced Raman scattering (SERS) experiments. Gold caps on silicon nanowires are hemispherical and only a few tens of nanometers in diameter when grown from metal catalysts by the vapor-liquid-solid growth mechanism using chemical vapor deposition. These gold caps are capable of enhancing Raman signals based on the surface-enhanced Raman scattering effect. The Raman signal can be enhanced even further (by at least one order of magnitude) when silver is selectively deposited onto these gold caps by autometallography (electroless deposition). By changing the silver deposition conditions, different coating morphologies can be realized on the gold caps that range from very thin, smooth layers to uneven and extremely rough coatings. The SERS signal enhancement and the spatial homogeneity of the achievable enhancement are compared for the different silver coatings using a model dye molecule. [source] | |||||||||||||||||||||||||||||||