Download or read book Observation of Surface Enhanced Raman Scattering for Transition Metal Hexaammine Cations at the Outer Helmholtz Plane Implications for Enhancement Mechanisms at Electrochemical Interfaces written by M. A. Tadayyoni and published by . This book was released on 1983 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent observation of surface-enhanced Raman scattering (SERS) for a variety of adsorbates at silver in electrochemical and gas-phase environments has generated a plethora of theoretical models to account for the remarkable (ca. 1,000,000 fold) observed enhancement of the Raman scattering intensities. These models can be divided into those demanding only the presence of the Raman scatterer at or close to the metal surface ('physical models'), and those requiring specific adsorbate-surface interactions ('chemical models'). Prompted in part by the especially intense SERS seen for specifically adsorbed species at silver electrodes, a widely held viewpoint is that the enhancement is due in part to chemical interactions between the Raman scatterer and the metal surface, possibly involving as adsorbate-adatom 'complex'. The report examines SERS of inorganic adsorbates at silver-aqueous interfaces. One objective is to examine systematically how the SER spectra are influenced by the nature of the adsorbate-surface interactions. A valuable class of adsorbates for this purpose is provided by substitutionally-inert Cr(III), Co(III), Ru(III) and Os(III) ammine complexes containing ligands such as thiocyanate, bromide, or pyrazine that bind strongly to silver electrodes.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1984 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Journal of Chemical Physics written by and published by . This book was released on 1984-06 with total page 1118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Understanding Surface enhanced Raman Scattering Using a Raman Bond Model written by Ran Chen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface-enhanced Raman scattering (SERS) is widely applied because of its high sensitivity and chemical specificity. SERS enhancements arise from two complementary mechanisms: the electromagnetic mechanism (EM) and the chemical mechanism (CM). EM helps to explain the high sensitivity, and the chemical specificity is mainly explained by CM. In EM, SERS enhancements are explained by local field enhancements due to surface plasmons and SERS enhancements approximately scale with field enhancements to the fourth power. In CM, SERS enhancements are attributed to bonding interactions between molecules and metal, and electronic structure simulations are usually applied to evaluate chemical enhancements. CM models have been developed to interpret chemical enhancements based on electronic structure simulations, and a transition based interpretation is shared by most of the models. In the transition based interpretation, chemical enhancements are explained by molecular transitions with decreased energy gaps and new emerged charge transfer transitions. Such transition based interpretation works well when specific transitions can be identified as the main contributions to the enhancements. However, when a large number of transitions contribute, a quantitative explanation requires an analysis of many transitions while a simple explanation is made by focusing on few transitions. To build a simple and quantitative interpretation of chemical enhancements, we develop a Raman bond model. The Raman bond model adopts Hirshfeld partitioning and charge density localization to express polarizability derivatives as charge flow modulations named Raman bonds. Chemical enhancements can accordingly be explained by Raman bonds near molecule-metal interfaces, and a charge based interpretation is obtained. The Raman bond model is demonstrated to work consistently for different types of molecule-metal bonds, different resonance conditions, and model systems with or without periodic conditions. Model systems consisting of pyridine, thiol, carbene, and CO molecules with localized clusters or periodic slabs are studied at different excitation frequencies and applied electric fields. Various factors such as electric fields, chemical substitutions, molecular structures, excitation frequencies, surface coverages, and surface roughness are consistently explained by Raman bond distributions near molecule-metal interfaces. Stronger chemical enhancements can be achieved by increasing the Raman bond conjugation near molecule-metal interfaces. The Raman bond model also helps quantify different enhancement mechanisms by mapping Raman bonds in the molecule, the inter-fragment bond, and the metal to enhancement contributions of molecular, charge transfer, and plasmon resonance. The mapping interprets EM as charge flow modulations in the metal. Such interpretation of EM may provide insights for building one holistic theory of SERS which includes CM and EM in a full quantum mechanical theory. The Raman bond model also reveals a linear correlation between chemical enhancements and inter-fragment charge flows to the fourth power. Based on the correlation, we show that SERS spectra of localized and periodic systems normalized by inter-fragment charge flows can be unified.
Download or read book Nanoscale Materials written by Luis M. Liz-Marzán and published by Springer Science & Business Media. This book was released on 2007-05-08 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organized nanoassemblies of inorganic nanoparticles and organic molecules are building blocks of nanodevices, whether they are designed to perform molecular level computing, sense the environment or improve the catalytic properties of a material. The key to creation of these hybrid nanostructures lies in understanding the chemistry at a fundamental level. This book serves as a reference book for researchers by providing fundamental understanding of many nanoscopic materials.
Download or read book Surface enhanced Raman Scattering from a Modified Silver Electrode written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical and spectroelectrochemical data was obtained for a silver electrode modified with oxazine 720. A quasi-reversible redox behaviour was observed for the modified electrode. Surface adsorption density, calculated from the measured electrochemical charge transfer, is higher than would be expected for a monolayer of flat-adsorbed oxazine 720. Surface-enhanced Raman scattering (SERS) data, in conjunction with results of a density functional theory (DFT) calculation, suggest that the molecule is adsorbed with its rings perpendicular to the electrode surface, consistent with the electrochemically estimated adsorption density. SERS was recorded in situ at different applied potentials. The SERS intensity remains relatively stable between -200 and -500 mV (versus AglAgCl Cl-sat), but decreases dramatically as the applied potential is made more negative than -500 mV. Ths is consistent with the onset of oxazine 720 reduction observed during cyclic voltammetry. The spectroelectrochemical data indicates that oxazine 720 remains adsorbed at the SERS-active sites even in its reduced form. Similar in situ SERS data was collected for rhodamine 6G and pyridine. Spectra in the Stokes and anti-Stokes regions were obtained at several applied potentials using two different laser excitation energies. Normalized ratios of the anti-Stokes to Stokes intensities were calculated for various vibrational bands of the three molecules. The measured ratios vary with changes in the excitation energy, the applied voltage and the energy of the vibrational mode being investigated. The ratios for oxazine 720 show a preferential enhancement of the Stokes scattering while the ratios for rhodamine 6G indicate an enhancement of the anti-Stokes scattering. For pyridine, the preferential enhancement changes between Stokes and anti-Stokes depending on the excitation wavelength used, the applied voltage and the vibrational band being examined. The main trends of the anti-Stokes to Stokes ratios ca.
Download or read book Green Corrosion Inhibitors written by V. S. Sastri and published by John Wiley & Sons. This book was released on 2012-02-14 with total page 267 pages. Available in PDF, EPUB and Kindle. Book excerpt: A book to cover developments in corrosion inhibitors is long overdue. This has been addressed by Dr Sastri in a book which presents fundamental aspects of corrosion inhibition, historical developments and the industrial applications of inhibitors. The book deals with the electrochemical principles and chemical aspects of corrosion inhibition, such as stability of metal complexes, the Hammett equation, hard and soft acid and base principle, quantum chemical aspects and Hansch' s model and also with the various surface analysis techniques, e.g. XPS, Auger, SIMS and Raman spectroscopy, that are used in industry for corrosion inhibition. The applications of corrosion inhibition are wide ranging. Examples given in this book include: oil and gas wells, petrochemical plants, steel reinforced cement, water cooling systems, and many more. The final chapters discuss economic and environmental considerations which are now of prime importance. The book is written for researchers in academia and industry, practicing corrosion engineers and students of materials science, engineering and applied chemistry.
Download or read book TiO2 Photocatalysis written by Akira Fujishima and published by . This book was released on 1999 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aquatic Redox Chemistry written by Paul Tratnyek and published by OUP USA. This book was released on 2012-06-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a comprehensive overview of aquatic redox chemistry through chapters contributed by many of the leading investigators in the field.
Download or read book Scanning Electrochemical Microscopy written by Allen J. Bard and published by CRC Press. This book was released on 2001-04-18 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning Electrochemical Microscopy describes the theory and operating principles of scanning electrochemical microscopy (SECM), including instrumentation, tip preparation, imaging techniques and potentiometric probes. The book explores applications relevant to electron transfer reactions, reaction kinetics, chemical events at interfaces, biologica
Download or read book Electrochemistry of Carbon Electrodes written by Richard C. Alkire and published by John Wiley & Sons. This book was released on 2015-11-23 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book sets the standard on carbon materials for electrode design. For the first time, the leading experts in this field summarize the preparation techniques and specific characteristics together with established and potential applications of the different types of carbon-based electrodes. An introductory chapter on the properties of carbon together with chapters on the electrochemical characteristics and properties of the different modifications of carbon such as carbon nanotubes, graphene, carbon fiber, diamond or highly ordered pyrolytic graphite provide the reader with the basics on this fascinating and ubiquitous electrode material. Cutting-edge technologies such as carbon electrodes in efficient supercapacitors, Li-ion batteries and fuel cells, or electrodes prepared by screen-printing are discussed, giving a complete but concise overview about the topic. The clearly structured book helps newcomers to grasp easily the principles of carbon-based electrodes, while researchers in fundamental and applied electrochemistry will find new ideas for further research on related key technologies.
Download or read book Polyelectrolytes written by Visakh P. M. and published by Springer. This book was released on 2014-09-03 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a valuable reference source to graduate and post graduate students, engineering students, research scholars polymer engineers from industry. The book provides the reader with current developments of theoretical models describing the thermodynamics polyelectrolytes as well as experimental findings. A particular emphasis is put on the rheological description of polyelectrolyte solutions and hydrogels.
Download or read book The Aromatic Sextet written by Erich Clar and published by John Wiley & Sons. This book was released on 1972 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aryl Diazonium Salts written by Mohamed Mehdi Chehimi and published by John Wiley & Sons. This book was released on 2012-07-10 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diazonium compounds are employed as a new class of coupling agents to link polymers, biomacromolecules, and other species (e. g. metallic nanoparticles) to the surface of materials. The resulting high performance materials show improved chemical and physical properties and find widespread applications. The advantage of aryl diazonium salts compared to other surface modifiers lies in their ease of preparation, rapid (electro)reduction, large choice of reactive functional groups, and strong aryl-surface covalent bonding. This unique book summarizes the current knowledge of the surface and interface chemistry of aryl diazonium salts. It covers fundamental aspects of diazonium chemistry together with theoretical calculations of surface-molecule bonding, analytical methods used for the characterization of aryl layers, as well as important applications in the field of electrochemistry, nanotechnology, biosensors, polymer coatings and materials science. Furthermore, information on other surface modifiers (amines, silanes, hydrazines, iodonium salts) is included. This collection of 14 self-contained chapters constitutes a valuable book for PhD students, academics and industrial researchers working on this hot topic.
Download or read book Calcium Phosphates in Biological and Industrial Systems written by Zahid Amjad and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calcium Phosphates in Biological and Industrial Systems provides a comprehensive discussion on calcium phosphates in the diverse areas of their applications. The authors are all respected specialists in their particular fields, possessing wide knowledge and experience and able to analyze recent results and relate them to their respective areas of expertise. New information, as well as a review of current concepts, highlights the individual contributions. Due to the broad scope of the subject covered and the large number of contributions, this book is divided into three parts. Whilst each section contains a basic theme, there is a considerable overlapping of ideas and approaches. This reflects the excitement and interdisciplinary nature of investigations by researchers interested in dissimilar aspects of calcium phosphates. Considering the general interest in calcium phosphates, Calcium Phosphates in Biological and Industrial Systems is directed at an audience of researchers in the fields of biology, chemistry, dentistry, geology, chemical engineering, environmental engineering, and medicine. It will also be useful to technology-focused researchers in industry whose investigations might be related directly or indirectly to calcium phosphates.
Download or read book Handbook on Characterization of Biomass Biowaste and Related By products written by Ange Nzihou and published by Springer Nature. This book was released on 2020-02-17 with total page 1394 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides authoritative information, techniques and data necessary for the appropriate understanding of biomass and biowaste (understood as contaminated biomass) composition and behaviour while processed in various conditions and technologies. Numerous techniques for characterizing biomass, biowaste and by-product streams exist in literature. However, there lacks a reference book where these techniques are gathered in a single book, although such information is in increasingly high demand. This handbook provides a wealth of characterization methods, protocols, standards, databases and references relevant to various biomass, biowaste materials and by-products. It specifically addresses sampling and preconditioning methods, extraction techniques of elements and molecules, as well as biochemical, mechanical and thermal characterization methods. Furthermore, advanced and innovative methods under development are highlighted. The characterization will allow the analysis, identification and quantification of molecules and species including biomass feedstocks and related conversion products. The characterization will also provide insight into physical, mechanical and thermal properties of biomass and biowaste as well as the resulting by-products.
Download or read book Electrical Engineering And Automation Proceedings Of The International Conference On Electrical Engineering And Automation Eea2016 written by Xiaoxing Zhang and published by World Scientific. This book was released on 2017-04-12 with total page 1140 pages. Available in PDF, EPUB and Kindle. Book excerpt: 2016 International Conference on Electrical Engineering and Automation (EEA2016) was held in Hong Kong, China from June 24th-26th, 2016. EEA2016 has provided a platform for leading academic scientists, researchers, scholars and students around the world, to get together to compare notes, and share their results and findings, in areas of Electronics Engineering and Electrical Engineering, Materials and Mechanical Engineering, Control and Automation Modeling and Simulation, Testing and Imaging, Robotics, Actuating and Sensoring.The conference had received a total of 445 submissions. However, after peer review by the Technical Program Committee only 129 were selected to be included in this conference proceedings; based on their originality, ability to test ideas, and contribution to the understanding and advancement in Electronics and Electrical Engineering.
