Download or read book Theoretical Investigations of Scanning Tunneling Microscopy of Adsorbates on Metal Surfaces written by and published by . This book was released on 2001 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scanning Tunneling Microscopy and Computational Chemistry Studies for Controlled Reactions on Silicon written by Dimitri B. Skliar and published by ProQuest. This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of the chemistry of silicon surfaces has been one of the major contributors in development and improvement of silicon based microelectronic devices in the past several decades. Progressively, the dimensions of devices have reduced by several orders of magnitude, presently at the length scale of few tens of nanometers, and are expected to decrease in size even more. For chemistry based film growth methods such as chemical vapor deposition (CVD) or atomic layer deposition (ALD), control of film structure and composition in this spatial regime requires a very detailed nanoscopic understanding of silicon surface chemistry. A combined experimental and theoretical approach, utilizing ultra high vacuum scanning tunneling microscopy (UHV-STM) and density functional theory (DFT), to understanding the surface chemistry of Si(100) is illustrated in the context of ALD development for high dielectric constant metal oxides. As a first possible route to controllably deposit monolayer thick metal layer, the reaction of the metal-organic molecule with bare silicon surface is considered. The interaction of the protonated b-diketonate ligand, 2,2,6,6-tetramethyl-3,5-heptanedione (dpmH), which is a byproduct of the strontium metal-organic precursor vaporization, with Si(100)-2x1 surface is investigated. Two aspects of the molecule's interactions were addressed: the adsorption at room temperature as well as its thermal decomposition. By combination of the experiments with DFT calculations of adsorbate geometry, STM image simulations, and reaction pathways it was possible to propose unique binding configurations that match the experimentally observed adsorption features. Theoretical analysis of multiple competing reaction pathways showed that hydroxyl dissociation via a 1,7 H-shift mechanism is the dominant adsorption pathway. Several other pathways including [2+4] addition, [2+2] C=O intra-dimer addition, [2+2] C=O intra-dimer addition with OH dissociation on an adjacent dimer, [2+2] C=C intra-dimer addition, and "ene" addition are found to be barrierless with respect to the entrance channel, and have small barriers relative to a hypothesized adsorption precursor intermediate. Pathways involving 1,3 and 1,2 intra-molecular H-shifts are found to be highly activated and are expected to be inaccessible at room temperature. Several state inter-conversions are found to be unlikely as well. These results provide insight to the competitive adsorption pathways for multifunctional molecules on silicon. Investigations of thermally induced decomposition of adsorbed dpmH molecules showed that there are no significant products of desorption of carbon containing fragments of the molecule, i.e. most of the carbon atoms incorporate into the silicon surface causing it to reconstruct to a c(4x4) phase at exposures below ~ 0.15 L. At higher exposures formation of SiC islands is observed. These findings demonstrate that schemes to deposit materials from organometallic compounds containing b-diketone ligands onto clean Si(100)-2x1 surface cannot result in an ordered interfacial structure as carbon incorporation into the substrate is inevitable. An alternative strategy for depositing metal template layer is proposed, where the initial reacting surface will be terminated by water at room temperature. The stability of surface hydroxyl groups and mechanisms of their decomposition in 300-600K temperature range are analyzed. It is found that surface oxidation does not follow first order kinetics with respect to the hydroxyl groups. DFT calculations of oxygen insertion pathways point towards a catalytic effect of the dangling bonds and suggest that in the 500-550K range the insertion events should occur predominantly next to unoccupied surface silicon sites. A model is proposed, where diffusing dangling bonds act as moving catalysts for hydroxyl group decomposition. Kinetic Monte Carlo (kMC) simulations are used to compare the results of this model with experimental data. A strategy to increase hydroxyl group stability is demonstrated where the initial concentration of surface dangling bonds is decreased by water termination at 130K.
Download or read book Scanning Tunneling Microscopy Studies of Growth and Adsorption on Transition Metal Surfaces written by Morten Østergaard Pedersen and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scanning Tunneling Microscopy in Surface Science Nanoscience and Catalysis written by Michael Bowker and published by John Wiley & Sons. This book was released on 2009-11-11 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, top international authors in the field of STM and surface science present first-class contributions on this hot topic, bringing the reader up to date with the latest developments in this rapidly advancing field. The focus is on the nanoscale, particularly in relation to catalysis, involving developments in our understanding of the nature of the surfaces of oxides and nanoparticulate materials, as well as adsorption, and includes in-situ studies of catalysis on such model materials. Of high interest to practitioners of surface science, nanoscience, STM and catalysis.
Download or read book Scanning Tunneling Microscopy Studies of Chemisorbed Layers of Metal Surfaces written by David Mark Zeglinski and published by . This book was released on 1990 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Analysis with STM and AFM written by Sergei N. Magonov and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are powerful tools for surface examination. In the past, many STM and AFM studies led to erroneous conclusions due to lack of proper theoretical considerations and of an understanding of how image patterns are affected by measurement conditions. For this book, two world experts, one on theoretical analysis and the other on experimental characterization, have joined forces to bring together essential components of STM and AFM studies: The practical aspects of STM, the image simulation by surface electron density plot calculations, and the qualitative evaluation of tip-force induced surface corrugations. Practical examples are taken from: * inorganic layered materials * organic conductors * organic adsorbates at liquid-solid interfaces * self-assembled amphiphiles * polymers This book will be an invaluable reference work for researchers active in STM and AMF as well as for newcomers to the field.
Download or read book Scanning Tunneling Microscopy and Its Application written by Chunli Bai and published by Springer. This book was released on 2010-12-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a unified view of the rapidly growing field of scanning tunneling microscopy and its many derivatives. After examining novel scanning-probe techniques and the instrumentation and methods, the book provides detailed accounts of STM applications. It examines limitations of the present-day investigations and provides insight into further trends. "I strongly recommend that Professor Bai's book be a part of any library that serves surface scientists, biochemists, biophysicists, material scientists, and students of any science or engineering field...There is no doubt that this is one of the better (most thoughtful) texts." Journal of the American Chemical Society (Review of 1/e)
Download or read book Toward Quantitative STM written by and published by . This book was released on 1995 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: STM was applied to chemisorbed S layers on Re(000l) and Mo(100) surfaces. As function of coverage on both these surfaces, S orders into several different overlayer structures, which have been studied by dynamic LEED. STM images of all these structures were obtained. Approximate location of S atoms in the structures was determined by inspecting the images, especially the regions containing defects. Results are in agreement with LEED except for the p(2 x l) overlayer of sulfur on Mo(100). The STM images were compared to calculations made with Electron Scattering Quantum Chemistry (ESQC) theory. Variation of contrast in experimental images is explained as a result of changes in STM tip termination structure. STM image contrast is a result of changes in the interference between different paths for the tunneling electrons. The simplest structure on the Mo(100) surface was used as a model for developing and testing a method of quantitative structure determination with the STM. Experimental STM images acquired under a range of tunneling conditions were compared to theoretical calculations of the images as a function of surface structure to determine the structure which best fit. Results matched within approximately 0.1 Angstroms a LEED structural determination. At lower S coverage, diffusion of S atoms over the Re(0001) surface and the lateral interaction between these atoms were investigated by application of a new image analysis technique. The interaction between the S and a coadsorbed CO layer was also studied, and CO was found to induce compression of the S overlayer. A similar result was found for Au deposited on the sulfur covered Mo(100) surface. The interaction between steps on the Mo surface was found to be influenced by S adsorption and this observation was interpreted with the theory of equilibrium crystal shape. Design of an STM instrument which operates at cryogenic and variable sample temperatures, and its future applications, are described.
Download or read book Scanning Tunneling Microscopy I written by and published by . This book was released on 1994 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scanning Tunneling Microscopy written by Joseph A. Stroscio and published by Academic Press. This book was released on 2013-10-22 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning tunneling microscopy (STM) and its extensions have become revolutionary tools in the fields of physics, materials science, chemistry, and biology. These new microscopies have evolved from their beginnings asresearch aids to their current use as commercial tools in the laboratory and on the factory floor. New wonders continue to unfold as STM delivers atomic scale imaging and electrical characterization of the newly emerging nanometer world. This volume in the METHODS OF EXPERIMENTAL PHYSICS Series describes the basics of scanning tunneling microscopy, provides a fundamental theoretical understanding of the technique and a thorough description of the instrumentation, and examines numerous examples and applications. Written by the pioneers of the field, this volume is an essential handbook for researchers and users of STM, as well as a valuable resource for libraries.
Download or read book Scanning Tunneling Microscopy written by Karl R. Koops and published by . This book was released on 1992 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structures and Dynamics of Atomic and Molecular Adsorbates on Metal Surfaces by Scanning Tunneling Microscopy and Low Energy Electron Diffraction written by Hyungsuk Alexander Yoon and published by . This book was released on 1996 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structures and Dynamics of Atomic and Molecular Adsorbates on Metal Surfaces by Scanning Tunneling Microscopy and Low Energy Electron Diffraction written by and published by . This book was released on 1996 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of surface structure and dynamics of atoms and molecules on metal surfaces are presented. My research has focused on understanding the nature of adsorbate-adsorbate and adsorbate-substrate interactions through surface studies of coverage dependency and coadsorption using both scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The effect of adsorbate coverage on the surface structures of sulfur on Pt(111) and Rh(111) was examined. On Pt(111), sulfur forms p(2x2) at 0.25 ML of sulfur, which transforms into a more compressed ((square root)3x(square root)3)R30° at 0.33 ML. On both structures, it was found that sulfur adsorbs only in fcc sites. When the coverage of sulfur exceeds 0.33 ML, it formed more complex c((square root)3x7)rect structure with 3 sulfur atoms per unit cell. In this structure, two different adsorption sites for sulfur atoms were observed - two on fcc sites and one on hcp site within the unit cell.
Download or read book Investigation of Single Functional Molecules on Metal Surfaces by Scanning Tunneling Microscopy written by Johannes Mielke and published by . This book was released on 2013 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scanning Tunneling Microscopy II written by Roland Wiesendanger and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and the broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those in STM I, these studies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described in chapters on scanning force microscopy, magnetic force microscopy, and scanning near-field optical microscopy, together with a survey of other related techniques. Also discussed here is the use of a scanning proximal probe for surface modification. Together, the two volumes give a comprehensive account of experimental aspects of STM and provide essential reading and reference material. In this second edition the text has been updated and new methods are discussed.
Download or read book Scanning Tunneling Microscopy I written by Hans-Joachim Güntherodt and published by Springer Science & Business Media. This book was released on 2013-03-13 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the first edition of "Scanning 'funneling Microscopy I" has been pub lished, considerable progress has been made in the application of STM to the various classes of materials treated in this volume, most notably in the field of adsorbates and molecular systems. An update of the most recent develop ments will be given in an additional Chapter 9. The editors would like to thank all the contributors who have supplied up dating material, and those who have provided us with suggestions for further improvements. We also thank Springer-Verlag for the decision to publish this second edition in paperback, thereby making this book affordable for an even wider circle of readers. Hamburg, July 1994 R. Wiesendanger Preface to the First Edition Since its invention in 1981 by G. Binnig, H. Rohrer and coworkers at the IBM Zurich Research Laboratory, scanning tunneling microscopy (STM) has devel oped into an invaluable surface analytical technique allowing the investigation of real-space surface structures at the atomic level. The conceptual simplicity of the STM technique is startling: bringing a sharp needle to within a few Angstroms of the surface of a conducting sample and using the tunneling cur rent, which flows on application of a bias voltage, to sense the atomic and elec tronic surface structure with atomic resolution! Prior to 1981 considerable scepticism existed as to the practicability of this approach.
Download or read book Scanning Tunneling Microscopy Investigations of Metal Dichalcogenide Materials written by and published by . This book was released on 1993 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have been used to characterize the atomic level structure of electronic properties, reactivity and wear of metal dichalcogenide materials that are or have potential as solid state lubricants. Single crystals Of MoS2, Ni(x)Mo(l-x) S2, MoS(2-x)Se(x) and MoS(2-x)Te(x) have been prepared to determine how chemical modifications affect the local structure and electronic properties of this lubricant. STM images of Ni-doped MoS2 show localized electronic states due to the Ni atoms, while images of Se- and Te-doped materials indicate that anion substitution is electronically delocalized. AFM studies of Te-doped MoS2 show, however, that the tellurium dopants form atomic scale structural protrusions that may reduce sliding friction. AFM has also been used to characterize nanometer scale wear and oxidation on MoS2 and NbSe2 surfaces. In atmosphere at room-temperature AFM studies showed that NbSe2 wears approximately three times faster than MoS2. Furthermore, oxidation studies demonstrated that NbSe2 was significantly more reactive than MoS2 with molecular oxygen. These results indicate that the intrinsic stability of the MoS2 surface make it an effective lubricant, AFM was also used to elucidate the growth of MoO3 on the surface Of MoS2 during oxidation, and to study wear properties of these MoO3 crystallites. The AFM tip was used to define lines with 10 nm resolution in MoO3 and to manipulate distinct MoO3 structures on the MoS2 surface. In addition, metal- substitution in TaS2 has been studied systematically using STM and theoretical methods.
