Surface-Enhanced Raman Scattering from Model Acrylic Adhesive Systems PDF Download
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Author:
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Category :
Languages : en
Pages : 34
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Book Description
Surface-enhanced Raman scattering (SERS) has been observed from a model acrylic adhesive deposited onto silver island films. SERS spectra of the adhesive system were very similar to SERS spectra of o-benzoic sulphimide (saccharin), a component of the curing system of the adhesive, and to normal Raman spectra of the sodium salt of saccharin. When saccharin was replaced in the curing system by benzoic acid, SERS spectra of the adhesive were similar to SERS spectra of benzoic acid and to normal Raman spectra of benzoic acid salts. The intensity of the SERS spectra was independent of the thickness of the adhesive films, indicating that the observed Raman signal was characteristic of the interface and not of the bulk of the films. These results demonstrate that saccharin and benzoic acid wee preferentially adsorbed at the silver surface to form metal salts and that surface-enhanced Raman scattering can be used for non- destructive characterization of interphases between polymer films and SERS- active metal substrates as long as the films are not so thick that normal Raman scattering from the bulk is comparable in intensity to the SERS from the interphase.
Author:
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ISBN:
Category :
Languages : en
Pages : 34
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Book Description
Surface-enhanced Raman scattering (SERS) has been observed from a model acrylic adhesive deposited onto silver island films. SERS spectra of the adhesive system were very similar to SERS spectra of o-benzoic sulphimide (saccharin), a component of the curing system of the adhesive, and to normal Raman spectra of the sodium salt of saccharin. When saccharin was replaced in the curing system by benzoic acid, SERS spectra of the adhesive were similar to SERS spectra of benzoic acid and to normal Raman spectra of benzoic acid salts. The intensity of the SERS spectra was independent of the thickness of the adhesive films, indicating that the observed Raman signal was characteristic of the interface and not of the bulk of the films. These results demonstrate that saccharin and benzoic acid wee preferentially adsorbed at the silver surface to form metal salts and that surface-enhanced Raman scattering can be used for non- destructive characterization of interphases between polymer films and SERS- active metal substrates as long as the films are not so thick that normal Raman scattering from the bulk is comparable in intensity to the SERS from the interphase.
Author: F. J. Boerio
Publisher:
ISBN:
Category :
Languages : en
Pages : 3
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Book Description
Surface-enhanced Raman scattering (SERS) is an analytical technique in which the Raman scattering cross-sections of molecules adsorbed onto the roughened surfaces of certain metals are enhanced by as much as six orders of magnitude compared to their value for normal Raman scattering. Many models have been proposed to explain SERS, but it is now considered that most of the enhancement is related to two mechanisms. The first is associated with the large electric fields that can be induced at the surfaces of metal particles having small radii of curvature. The second is associated with formation of charge-transfer complexes between the adsorbed molecules and the substrate. Enhancement due to the charge transfer mechanism is obtained only for molecules immediately adjacent to the surface, but enhancement due to electromagnetic mechanism may extend several monolayers away from the surface. Considering that normal Raman scattering by polymers is weak and that scattering by molecules adjacent to the substrate is strongly enhanced, it is evident that SERS can be used for non-destructive characterization of interfaces between polymer films and metals as long as the films are not so thick that scattering by the bulk of the film is comparable in intensity to SERS from the interface. Keywords: DD Form 1473, Nondestructive characterization, Polymer/Metal interfaces, Surface-enhanced raman scattering, SERS, Adsorption, Silver, Acrylic adhesive system.
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Category : Aeronautics
Languages : en
Pages : 1460
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: David A. Dillard
Publisher: Elsevier
ISBN: 1845698053
Category : Technology & Engineering
Languages : en
Pages : 654
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Book Description
Adhesive bonding is often effective, efficient, and often necessary way to join mechanical structures. This important book reviews the most recent improvements in adhesive bonding and their wide-ranging potential in structural engineering.Part one reviews advances in the most commonly used groups of structural adhesives with chapters covering topics such as epoxy, polyurethane, silicone, cyanoacrylate, and acrylic adhesives. The second set of chapters covers the various types of adherends and pre-treatment methods for a range of structural materials such as metals, composites and plastics. Chapters in Part three analyse methods and techniques with topics on joint design, life prediction, fracture mechanics and testing. The final group of chapters gives useful and practical insights into the problems and solutions of adhesive bonding in a variety of hostile environments such as chemical, wet and extreme temperatures.With its distinguished editor and international team of contributors, Advances in structural adhesive bonding is a standard reference for structural and chemical engineers in industry and the academic sector. - Reviews advances in the most commonly used groups of structural adhesives including epoxy, silicone and acrylic adhesives - Examines key issues in adhesive selection featuring substrate compatibility and manufacturing demands - Documents advances in bonding metals, plastics and composites recognising problems and limitations
Author:
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Category :
Languages : en
Pages : 27
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Book Description
Surface-enhanced Raman scattering (SERS) is a process in which the Raman scattering cross section of molecules adsorbed onto the surfaces of metals such as silver, copper, and gold is increased by as much as six orders of magnitude. However, the enhancement is short-range and is restricted to the first few layers of molecules adjacent to the surface. As a result, SERS can be used to characterize adsorption of organic compounds onto metals and can be used for non-destructive characterization of interfaces between polymer films and metal substrates as long as the polymer films are not so thick that normal Raman scattering from the bulk of the film is more intense than SERS from the interface. SERS spectra were obtained from bilayers prepared by spin-coating thin films of polymers such as polystyrene onto silver island films and then overcoating them with much thicker films of a second polymer such as polystyrene sulfonate. The spectra were characteristic of the films adjacent to the silver and not the overlayers as long as the thickness of the films adjacent to the substrate was more than about 100 A in thickness. SERS spectra obtained from thick films of an acrylic adhesive spin-coated onto silver were identical to normal Raman spectra of salts of saccharin, a component of the cure system, and to SERS spectra of saccharin, indicating that saccharin segregated to the adhesive/substrate interface and adsorbed onto the substrate by dissociation. (aw).
Author: Pel-Pel Hong
Publisher:
ISBN:
Category :
Languages : en
Pages : 160
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Book Description
Author: Ivano Alessandri
Publisher: Frontiers Media SA
ISBN: 2889635538
Category :
Languages : en
Pages : 175
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Book Description
Author: Katrin Kneipp
Publisher: Springer Science & Business Media
ISBN: 3540335676
Category : Science
Languages : en
Pages : 473
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Book Description
Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This book summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.
Author: Ran Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Louis H. Sharpe
Publisher: CRC Press
ISBN: 1000725200
Category : Technology & Engineering
Languages : en
Pages : 822
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Book Description
First published in 1996. ADHESION INTERNATIONAL 1993 is a volume of the Proceedings of the 16th Annual Meeting of The Adhesion Society, Inc. Williamsburg, Virginia, USA February 21-26,1993. This meeting featured an International Symposium on The Interphase. Interphases are extremely important in many areas of technology. They are formed when dissimilar materials are joined and they control the properties of adhesive joints, composites, coatings, and microelectronics devices. Considering the importance and scope of phenomena associated with the interphase, it was appropriate to convene such a symposium at the meeting.
