Pure Beams Of Highly Vibrationally Excited Molecules

The grant was used to purchase, construct, and install necessary instrumentation to implement Hexapole focusing of laser prepared vibrationally excited molecules. It consists of three differentially pumped chamber, for: (1) state preparation, (2) hexapole filtering and (3) detection. In addition two Yag-pumped dye laser systems were purchased from Spectra-Physics and Sirah, which allow stimulated emission pumping to prepare highly vibrationally excited states of molecules. We have also dedicated another existing Yag-pumped dye laser system to the project for REMPI and LIF detection of the focused molecules.

Unimolecular Kinetics: Part 2: Collisional Energy Transfer and the Master Equation, Volume 43 in Elsevier’s Comprehensive Molecular Kinetics series, addresses collision energy transfer and the effects it has on gas phase reactions, particularly at low gas density. Such systems include combustion, industrial gas phase processes and atmospheric/environmental processes. The book also discusses The Master Equation to give a good overview of the mechanics underpinning unimolecular kinetics. This new volume will be of interest to researchers investigating gas phase processes which involve unimolecular reactions and the related intermolecular reactions. Discusses collision energy transfer and the effects it has on gas phase reactions Introduces stochastic techniques to energy transfer methods, allowing for an extension of the unimolecular theory beyond simple molecular dissociation Draws an important connection between detailed reaction dynamic studies and the rate of coefficient determination

This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level understanding of physical and chemical processes at surfaces, with particular emphasis on dynamical aspects. This book is a reference in the field.

Laser spectroscopy has been perfected over the last fifteen years to become a precise tool for the investigation of highly vibrationally excited molecules. Intense infrared laser radiation permits both the multiple-photon resonant excitation and the dissociation of polyatomic molecules. In this book, the latest results of some of the foremost Soviet researchers are published for the first time in the West. Laser Spectroscopy of Highly Vibrationally Excited Molecules contains a comprehensive study of both the experimental and theoretical aspects of the basic photophysical interactions that occur in these processes. The book first focuses on the nonlinear interaction between the resonant vibrational mode and the intense infrared field and then examines the nonlinear interaction between the vibrational modes themselves due to anharmonicity. These interrelated processes determine all the characteristics of polyatomic molecules in an infrared field. The book also discusses related phenomena such as spectra broadening, optical resonance, photon echoes, and dynamical chaos. It includes examples of multiple-photon resonant excitation such as the excitation of OsO4 by CO^O2 laser radiation, which is detected by the visible luminescence that results. This book will be of great interest to researchers and postgraduate students in infrared laser spectroscopy and the laser chemistry of molecules and applications of isotope separation.

A new method of producing a pulsed, cold beam of high velocity neutral molecules is shown to be feasible. A hollow container filled with a chosen gas is mechanically accelerated to a high velocity in a rifle or light gas gun. The container (called a sabot) is subsequently opened to allow the gas to emerge. The sabot is then slowed or deflected. Velocities up to about 3 km/sec can be achieved with a Super Swift rifle and up to about 10 km/sec with a light gas gun. It appears feasible to produce a pulsed beam at 10 km/sec with an angular divergence of = 2.5 degrees and a spread in velocity of = 4%. A 5 micro sec pulse with an instantaneous intensity of the order of 2 x 10 to the 23rd power molecules/sq cm -sec can be achieved. A beam of N2 crossed with a low velocity beam of CO or CO2 produces vibrationally excited molecules in sufficient quantity to be detected with state-of-the-art techniques. It appears feasible to measure the cross sections for collisional excitation of the vibrational levels of CO2 and CO by N2, and the cross sections for the exchange of vibrational energy between N2 and CO2 or CO. The total cross section, which gives the mean free path, can also be obtained. (Author).

A hyperthermal molecular beam apparatus, utilizing a heated seeded supersonic nozzle capable of producing fast intense beams of atmospheric species, has been employed to study vibrational excitation of plume species carbon dioxide and carbon monoxide. The apparatus is provided with a novel neutral beam detector for measurement of beam intensity and velocity distribution. The excitation mechanism is studied through monitoring of the infrared emission from the plume species by the use of lead sulfide, lead selenide, and indium antimonide. Lack of measurable signals is analyzed in terms of signal to noise ratios and it is shown that excitation cross sections generally have an upper limit of 10 to the 19th power per square centimeter showing that transfer of translational energy into internal energy does not take place efficiently. (Author).

25th International Congress of Pure and Applied Chemistry presents a compilation of papers covering a wide range of topics on applied and pure chemistry. This book discusses the challenges in the field of aromatic photosubstitution. Organized into six chapters, this book begins with an overview of the diverse reactions of aromatic molecules. This text then examines the pattern of specific RNA found in the human tumors, which showed a notable concordance with the predictions deducible from the animal system. Other chapters consider the methods of estimation of chemical fuels and describe the greenhouse effect arising from the burning of coal. This book presents as well an assessment of some features of the impact of quantum mechanics on chemistry. The final chapter deals with molecular beam and spectroscopic methods that allow a detailed investigation of several dynamical properties of single reactive collisions. This book is a valuable resource for chemists, theoreticians, research workers, and scientists.

While much of traditional surface science has been concerned with equilibrium properties and simple kinetics, there is a growing effort in the area of dynamical processes at surfaces. This book draws together a series of chapters written by acknowledged experts in the field, which describe progress in a range of specific topics. The emphasis is on chemical reaction dynamics, including both theoretical and experimental approaches and covering work on low index single crystal surfaces, on stepped surfaces and on supported metal clusters. Other processes, such as surface diffusion are also addressed. Further chapters discuss dynamical processes in electronically-induced desorption, and in surface diffusion on semiconductors and metals. - Presents considerable advances in surface science field - Collection of expert reviews in surface dynamics

Integrating both theoretical and experimental approaches, this unique book examines transition states and chemical reactivity, and will be a useful tool for anyone studying the chemical dynamics, nature, and behavior of molecules in an excited state. The subject has important applications in atmospheric chemistry, plasmas, high-temperature materials processing, combustion, photosynthesis, detonation, and explosives.