The interactions of vibrationally excited HCI(v =2) with MgO(100) surfaces have been examined in detail, with scattered HCI(v =2) detected state selectively by resonance enhanced multiphoton ionization (REMPI). Simulations using a random walk model and 'best estimates' for activation energies for desorption and hopping suggest that deactivation probably occurs at steps. In parallel, a new apparatus has been designed and built for a next generation of studies of molecular interactions on insulating oxide surfaces. Specifically, FTIR will be used to determine geometries and adsorption, and TPD, REMPI and other laser-based spectroscopies will be used to interrogate interactions of molecules and radicals with the surface and with other adsorbates.

Collision induced dissociation of highly excited NO2 was observed for the first time for well characterized MgO(100) surfaces with parent and product angular resolution at various internal and incident translational energies, and with product NO state-selected detection. A model was developed which explains the results, and enabled comparisons with the corresponding gas-phase experiments. Scattering of HCl(v=0) was examined at incident energies 0.11-0.90 eV, and demonstrated the transition between direct-inelastic scattering to trapping-desorption. At low incident energies rotational and translational temperatures of scattered HCl were equal to the surface temperature, and residence times in the millisecond regime were observed at low surface temperature. When HCl(v=2, J=1) was scattered from the surface, vibrational excitation survived the process of trapping-desorption, and HCl in v=2 was scattered into the gas phase. The residence time, however, was less than a microsecond at all temperatures. These results were reconciled with the scattering results of HCl in v=0 using a model that described the competition between hopping on terrace sites, desorption, and deactivation on defect sites.

Chemical sensors are integral to the automation of myriad industrial processes and everyday monitoring of such activities as public safety, engine performance, medical therapeutics, and many more. This 4 volume reference work covering simulation and modeling will serve as the perfect complement to Momentum Press's 6 volume reference works "Chemical Sensors: Fundamentals of Sensing Materials" and "Chemical Sensors: Comprehensive Sensor Technologies", which present detailed information related to materials, technologies, construction and application of various devices for chemical sensing. This 4 volume comprehensive reference work analyzes approaches used for computer simulation and modeling in various fields of chemical sensing and discusses various phenomena important for chemical sensing such as bulk and surface diffusion, adsorption, surface reactions, sintering, conductivity, mass transport, interphase interactions, etc. In this work it will be shown that theoretical modeling and simulation of the processes, being a basic for chemical sensors operation, could provide considerable progress in choosing both optimal materials and optimal configurations of sensing elements for using in chemical sensors. Each simulation and modeling volume in the present series reviews modeling principles and approaches peculiar to specific groups of materials and devices applied for chemical sensing. Volume 1: Microstructural Characterization and Modeling of Metal Oxides covers microstructural characterization of metal oxides using SEM, TEM, Raman spectroscopy and in-situ high temperature SEM, and multiscale atomistic simulation and modeling of metal oxides, including surface state, stability and metal oxide interactions with gas molecules, water and metals.

The first book to give a comprehensive account of the fundamental properties of metal-oxide surfaces.

Our long-term vision is for a comprehensive and fundamental understanding of a critical gas-surface reaction, nano-oxidation from the adsorption of oxygen atoms on the metal surface to the coalescence of the bulk oxide via coordinated multi-scale theoretical and in situ experimental efforts. Reaching this goal necessitates close collaborations between theorists and experimentalists, and the development and utilization of unique and substantial theoretical and experimental tools. Achievement of this goal will be a major breakthrough in dynamic surface/interface reactions that will dramatically impact several scientific fields. Many of these are of interest to DOE, such as thin films and nanostructures that use oxidation for processing, heteroepitaxy, oxidation and corrosion, environmental stability of nano-devices, catalysis, fuel cells and sensors. The purpose of this specific DOE program was the support for the theoretical effort. Our focus for the first round of funding has been the development of a Kinetic Monte Carlo (KMC) code to simulate the complexities of oxygen interactions with a metal surface. Our primary deliverable is a user-friendly, general and quite versatile KMC program, called Thin Film Oxidation (TFOx). TFOx-2D presently simulates the general behavior of irreversible 2-dimensional nucleation and growth of epitaxial islands on a square or rectangular lattice. The TFOx model explicitly considers a very large range of elementary steps, including deposition, adsorption, dissociation of gas molecules (such as O2), surface diffusion, aggregation, desorption and substrate-mediated indirect interactions between static adatoms. This capability allows for the description of the numerous physical processes involved in nucleation and growth. The large number of possible input parameters used in this program provides a rich environment for the simulation of epitaxial growth or oxidation of thin films. As a first demonstration of the power of TFOx-2D, the input parameters were systematically altered to observe how various physical processes impact morphologies. It was noted that potential gradients, developed to simulate medium-range substrate mediated interactions such as strain, and the probability of an adatom attaching to an island, have the largest effect on island morphologies. Nanorods, and round, square and dendritic shapes have all been observed which correlate well with experimental observations of the wide range of oxide morphologies produced during in situ oxidation of Cu thin films. To allow TFOx to be accessible to the rest of the scientific community, a web-site describing TFOx has been developed: www.tfox.org. Brief highlights of our progress to date are summarized as: Development of TFOx-2D, a versatile kinetic Monte Carlo code that can simulate atomistic transport, nucleation and growth, and includes potential gradients to simulate medium-range substrate mediated effects (e.g., strain); Systematic study of TFOx-2D input parameters to reveal a variety of nano-structures that resemble those seen experimentally; Parallelization of the Streitz-Mintmire potential and Rappe-Goddard approach for determining dynamic charge transfer at a metal-oxide interface, which is the critical step required for molecular dynamic simulations of oxygen-metal interactions; Benchmark calculations of Cu and Cu2O physical properties to determine the most accurate electronic structure approach; and, Demonstration of the greater universality of the Tersoff-Tromp elastic strain relief model of nano-rod formation to a gas-surface reaction. Hence, we have established the ground work for a truly comprehensive and multi-scale theoretical tool that can simulate any gas-surface reaction, including oxidation, from the atomic level to the mesoscale, from first principles. The direct comparison between these simulations and in situ experiments of metal nano-oxidation will lead to new knowledge of this important surface reaction.

Molecular surface science has made enormous progress in the past 30 years. The development can be characterized by a revolution in fundamental knowledge obtained from simple model systems and by an explosion in the number of experimental techniques. The last 10 years has seen an equally rapid development of quantum mechanical modeling of surface processes using Density Functional Theory (DFT). Chemical Bonding at Surfaces and Interfaces focuses on phenomena and concepts rather than on experimental or theoretical techniques. The aim is to provide the common basis for describing the interaction of atoms and molecules with surfaces and this to be used very broadly in science and technology. The book begins with an overview of structural information on surface adsorbates and discusses the structure of a number of important chemisorption systems. Chapter 2 describes in detail the chemical bond between atoms or molecules and a metal surface in the observed surface structures. A detailed description of experimental information on the dynamics of bond-formation and bond-breaking at surfaces make up Chapter 3. Followed by an in-depth analysis of aspects of heterogeneous catalysis based on the d-band model. In Chapter 5 adsorption and chemistry on the enormously important Si and Ge semiconductor surfaces are covered. In the remaining two Chapters the book moves on from solid-gas interfaces and looks at solid-liquid interface processes. In the final chapter an overview is given of the environmentally important chemical processes occurring on mineral and oxide surfaces in contact with water and electrolytes. - Gives examples of how modern theoretical DFT techniques can be used to design heterogeneous catalysts - This book suits the rapid introduction of methods and concepts from surface science into a broad range of scientific disciplines where the interaction between a solid and the surrounding gas or liquid phase is an essential component - Shows how insight into chemical bonding at surfaces can be applied to a range of scientific problems in heterogeneous catalysis, electrochemistry, environmental science and semiconductor processing - Provides both the fundamental perspective and an overview of chemical bonding in terms of structure, electronic structure and dynamics of bond rearrangements at surfaces