Download or read book The Behaviour and Interactions of the Silica water Interface Studied Through Nonlinear Optics written by Benjamin Rehl and published by . This book was released on 2020 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recognizing Molecules and Following Reactions at Interfaces Using the Nonlinear Optical Techniques Sum Frequency Generation and Second Harmonic Generation written by Zhiguo Li and published by . This book was released on 2015 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silica has been widely used as a solid support to generate functionalized silica in material science, which plays important roles in various areas such as catalysis and disease diagnostics. The applications of functionalized silica involve the special molecular properties of interfaces, which can differ from the properties of molecules in bulk phases. Nonlinear optical techniques, including second harmonic generation (SHG) and sum frequency generation (SFG), are a class of well-defined spectroscopic techniques that are well-suited to probe interfacial molecules and to study interfacial phenomena. Owing to their surface specificity, only the molecules that are ordered at the interface are probed in the measurement while interference from molecules in bulk phases is effectively excluded. Taking planar silica and functionalized planar silica as substrates, this thesis mainly focuses on characterizing the structure and order of molecules at these solid surfaces, and investigating the interaction between immobilized molecules and bulk phase molecules. Specifically, the binding of a model reactant 4-nitroacetophenone with amino and ureido organocatalytic monolayers on silica was investigated at the silica/acetonitrile interface using a combination of SHG and SFG, and the results reveal that the performance of immobilized catalysts is strongly affected by the local environment of surface molecules. Next, the Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) was followed at the silica/methanol interface using vibrational SFG; the reaction order with respect to copper catalyst was determined to be 2.1, suggesting that two coppers are involved in the rate-determining step of the interfacial reaction. Using a CuAAC attachment strategy, the thermal evolution of immobilized DNA single strands and duplexes were investigated at the silica/buffer interface using vibrational SFG. Consistent with our SHG work, the melting temperature of the immobilized T15:A15 (thymidine 15-mer: deoxyadenosine 15-mer) duplex at the interface is found to be ~ 12 °C lower than the solution phase melting temperature, indicating immobilization on silica destabilizes the DNA duplex. Finally, as silica is a commonly used stationary phase in chromatography, the organization of acetonitrile molecules at the silica/aqueous interface was studied using vibrational SFG. For a given solution composition, increasing the solution pH is found to effectively decrease the number density of interfacial acetonitrile molecule, which we attribute to the decrease in the number density of surface silanol which can form a hydrogen bond with cyanide within the acetonitrile molecule. Overall, these results demonstrate the study of interfacial phenomena involving self-assembled monolayers on insulated surfaces like silica using the nonlinear optical techniques SHG and SFG. The combination of these techniques represents a useful approach to explore similar systems in their relevant research areas.
Download or read book The Water amorphous Silica Interface written by Yun Kyung Shin and published by . This book was released on 2011 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Advances in the construction of nanoscale biomedical devices requires increasingly realistic descriptions of interactions with biomolecules, and with fluid flow within micro- and nanochannels. We have made progress in both areas for nanostructures fabricated from amorphous silica. Silica is a material commonly used to fabricate biomedical devices, and the interactions of silica with aqueous solutions and biomolecules are of great importance in many fields. We developed a tractable model for biomolecules at the water/amorphous silica interface. This interaction model is based on one previously developed for the amorphous silica/water interface. Quantum chemical calculations of a series of probe molecules that mimic the common functional groups found in biomolecules were performed near a characteristic silica fragment. Our interaction model was designed to best reproduce the quantum chemical results. Then we investigated binding of two tripeptides (lys-trp-lys and glu-trp-glu) at the amorphous silica/water interface using molecular dynamics simulations. The preliminary studies reveal the great variety of binding motifs possible when biomolecules interact with silica, and illustrate how a peptide with overall negative charge like glu-trp-glu might bind to silica by hydrophilic/hydrophobic interactions on the highly inhomogeneous silica surface.
Download or read book Summary Record of the 1162nd Meeting Chamber B Held at the Palais Wilson Geneva on Tuesday 12 September 2006 written by and published by . This book was released on 2006 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Sum Frequency Spectroscopy written by Y. R. Shen and published by Cambridge University Press. This book was released on 2016-02-18 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first book on the topic, and written by the founder of the technique, this comprehensive resource provides a detailed overview of sum-frequency spectroscopy, its fundamental principles, and the wide range of applications for surfaces, interfaces, and bulk. Beginning with an overview of the historical context, and introductions to the basic theory of nonlinear optics and surface sum-frequency generation, topics covered include discussion of different experimental arrangements adopted by researchers, notes on proper data analysis, an up-to-date survey commenting on the wide range of successful applications of the tool, and a valuable insight into current unsolved problems and potential areas to be explored in the future. With the addition of chapter appendices that offer the opportunity for more in-depth theoretical discussion, this is an essential resource that integrates all aspects of the subject and is ideal for anyone using, or interested in using, sum-frequency spectroscopy.
Download or read book Reactions and Interfacial Behaviors of the Water Amorphous Silica System from Classical and Ab Initio Molecular Dynamics Simulations written by Jessica M. Rimsza and published by . This book was released on 2016 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the wide application of silica based systems ranging from microelectronics to nuclear waste disposal, detailed knowledge of water-silica interactions plays an important role in understanding fundamental processes, such as glass corrosion and the long term reliability of devices. In this dissertation, atomistic computer simulation methods have been used to explore and identify the mechanisms of water-silica reactions and the detailed processes that control the properties of the water-silica interfaces due to their ability to provide atomic level details of the structure and reaction pathways. The main challenges of the amorphous nature of the silica based systems and nano-porosity of the structures were overcome by a combination of simulation methodologies based on classical molecular dynamics (MD) simulations with Reactive Force Field (ReaxFF) and density functional theory (DFT) based ab initio MD simulations. Through the development of nanoporous amorphous silica structure models, the interactions between water and the complex unhydroxylated internal surfaces identified the unusual stability of strained siloxane bonds in high energy ring structure defects, as well as the hydroxylation reaction kinetics, which suggests the difficulty in using DFT methods to simulate Si-O bond breakage with reasonable efficiency. Another important problem addressed is the development of silica gel structures and their interfaces, which is considered to control the long term residual dissolution rate in borosilicate glasses. Through application of the ReaxFF classical MD potential, silica gel structures which mimic the development of interfacial layers during silica dissolution were created A structural model, consisting of dense silica, silica gel, and bulk water, and the related interfaces was generated, to represent the dissolution gel structure. High temperature evolution of the silica-gel-water (SGW) structure was performed through classical MD simulation of the system, and growth of the gel into the water region occurred, as well as the formation of intermediate range structural features of dense silica. Additionally, hydroxylated silica monomers (SiO4H4) and longer polymerized silica chains were formed in the water region, indicating that glass dissolution is occurring, even at short time frames. The creation of the SGW model provides a framework for a method of identifying how interfacial structures which develop at glass-water interfaces can be incorporated into atomistic models for additional analysis of the dissolution of silicates in water.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 934 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies of Liquid solid Interfaces and of Bulk Liquids Using Second Harmonic Generation and THz Spectroscopy written by Shuo-Che Yang and published by . This book was released on 2000 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1974 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1970 with total page 1208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear Optics written by and published by Institute of Electrical & Electronics Engineers(IEEE). This book was released on 1994 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Current Awareness in Particle Technology written by and published by . This book was released on 1996 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1998 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal written by American Chemical Society and published by . This book was released on 2003 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
