This book provides a comprehensive and up-to-date account of the field of low energy positrons and positronium within atomic and molecular physics. It begins with an introduction to the field, discussing the background to low energy positron beams, and then covers topics such as total scattering cross sections, elastic scattering, positronium formation, excitation and ionisation, annihilation and positronium interactions. Each chapter contains a blend of theory and experiment, giving a balanced treatment of all the topics. The book will be useful for graduate students and researchers in physics and chemistry. It is ideal for those wishing to gain rapid, in-depth knowledge of this unique branch of atomic physics.

This book is an introduction to the physics of highly excited, easily perturbed or interacting atoms. The book begins with a brief introduction to the traditional view of electron shells and their properties, and then goes on to discuss Rydberg states, quantum defect theory, atomic f-values, centrifugal barrier effects, autoionisation, inner shell and double excitation spectra, K-matrix theory, atoms in high laser fields, statistical methods, quantum chaos, and atomic effects in solids. The emphasis is throughout on radial properties, orbital collapse, many body effects, the breakdown of the independent particle approach, the emergence of chaos, and the behaviour of atoms inside clusters and solids. A very full account of autoionisation includes not only the standard treatment for isolated resonances, but also several alternative approaches. The book discusses many experimental examples and has many diagrams and a comprehensive reference list.

This monograph presents a complete guide to the theory of modern spectroscopy of atoms. Atomic spectroscopy continues to be one of the most important subjects of contemporary physics. The book describes the contemporary state of the theory of many-electron atoms and ions, the peculiarities of their structure and spectra, the processes of their interaction with radiation, and some of the applications of atomic spectroscopy. It contains a large number of new results, which have been published mainly in Russian and are therefore almost unknown to western scientists. Primarily a reference for researchers and graduate students in atomic physics and physical chemistry, this work will also be of value to physicists and chemists in other areas who use spectroscopy in their work.

This book describes the manifestations of chaos in atoms and molecules. The study of chaos is today one of the most active and prolific areas in atomic physics. This is the first attempt to provide a coherent introduction to this fascinating area. In line with its scope, the book is divided into two parts. The first part (chapters 1–5) deals with the theory and principles of classical chaos. The ideas developed here are then applied to actual atomic and molecular physics systems in the second part of the book (chapters 6–10) covering microwave driven surface state electrons, the hydrogen atom in a strong microwave field, the kicked hydrogen atom, chaotic scattering with CsI molecules and the helium atom. The book contains many diagrams and a detailed references list.

This monograph describes the theory and practice of electron spectrometry using synchrotron radiation. The book is in three parts. After a short review of background theory, neon is used to elucidate the principles of the photoelectron and Auger spectra. The second part of the book looks at experimental aspects, including characteristic features of electrostatic analysers, detectors, lenses, disturbances, and optimisation, and then illustrates theory and experiment with details of recent experiments. The third part provides useful reference data, including wavefunctions, special theory, polarisation and special aspects of instrumentation. A detailed reference list completes the volume. The study of electron spectrometry using synchrotron radiation is a growing field of research driven by the increasing availability of advanced synchrotron radiation light sources and improved theoretical methods for solving the many-electron problem in atoms. This balanced account will be of value to both theorists and experimentalists working in this area.

This graduate/research level text introduces the theory of multi-electron transitions in atomic, molecular and optical physics, emphasising the emerging topic of dynamic electron correlation. The book begins with an overview of simple binomial probabilities, classical scattering theory, quantum scattering and correlation, followed by the theory of single electron transition probabilities. Multiple electron transition probabilities are then treated in detail. Various approaches to multiple electron transitions are covered including the independent electron approximation, useful statistical methods and perturbation expansions treating correlation in both weak and strong limits. The important topic of the dynamics of electron correlation is a central theme in this book. The text contains a comprehensive summary of data for few and many-electron transitions in atoms and molecules, including transitions on different atomic centres, fast ion-atom and electron-atom interactions, and recent observations using synchrotron radiation. Emphasis is given to methods that may be used by non-specialists.

This book is a comprehensive introduction to electron-atom collisions, covering both theory and experiment. The interaction of electrons with atoms is the field that most deeply probes both the structure and reaction dynamics of a many-body system. The book begins with a short account of experimental techniques of cross-section measurement. It then introduces the essential quantum mechanics background needed. The following chapters cover one-electron problems (from the classic particle in a box to a relativistic electron in a central potential), the theory of atomic bound states, formal scattering theory, calculation of scattering amplitudes, spin-independent and spin-dependent scattering observables, ionisation and electron momentum spectroscopy. The connections between experimental and theoretical developments are emphasised throughout.

This book explains the theory and methods by which gas molecules can be polarized by light, a subject of considerable importance for what it tells us about the electronic structure of molecules and properties of chemical reactions. Starting with a brief review of molecular angular momentum, the text goes on to consider resonant absorption, fluorescence, photodissociation and photoionization, as well as collisions and static fields. A variety of macroscopic effects are considered, among them angular distribution and the polarization of emitted light, ground state depopulation, laser-induced dichroism, the effect of collisions and external magnetic and electric field effects. Most examples in the book are for diatomic molecules, but symmetric-top polyatomic molecules are also included. The book concludes with a short appendix of essential formulae, tables for vector calculus, spherical functions, Wigner rotation matrices, Clebsch-Gordan coefficients, and methods for expansion over irreducible tensors.

In recent years, Rydberg atoms have been the subject of intense study, becoming the testing ground for several quantum mechanical problems. This book provides a comprehensive description of the physics of Rydberg atoms, highlighting their remarkable properties by reference to their behaviour in a wide range of physical situations. Following an overview of the basic properties of Rydberg atoms, their interactions with electric and magnetic fields are analysed in detail. The collisions of Rydberg atoms with neutral and charged species are described, and the use of multichannel quantum defect theory in the study of Rydberg atomic systems is discussed. Experimental and theoretical research in this extensive field is also reviewed, making the book valuable to both graduate students and established researchers in physics and physical chemistry.

This book reviews the present knowledge of collision-induced absorption of infrared radiation in the dense, common gases. Following a brief introduction and review of essential background information, such as dipole radiation, molecular collisions and interactions, numerous experimental results for the absorption spectra of dense gases are presented. Other chapters review the causes and properties of dipole moments induced by molecular interactions, the theory of collision-induced absorption in monatomic gas mixtures and in molecular gases and mixtures. The final chapter discusses related phenomena and the important applications in astrophysics. Throughout the book, the emphasis is on the absorption by binary molecular complexes, but the onset of many-body effects, such as the ternary contributions and the intercollisional process, are also considered. The volume is meant to be a practical guide and sourcebook for the researcher interested in the spectroscopy of dense, neutral fluids. This edition includes a new appendix reviewing recent work.

Photodissociation induced by the absorption of single photons permits the detailed study of molecular dynamics such as the breaking of bonds, internal energy transfer and radiationless transitions. The availability of powerful lasers operating over a wide frequency range has stimulated rapid development of new experimental techniques which make it possible to analyse photodissociation processes in unprecedented detail. This text elucidates the achievements in calculating photodissociation cross-sections and fragment state distributions from first principles, starting from multi-dimensional potential energy surfaces and the Schrödinger equation of nuclear motion. Following an extended introduction in which the various types of observables are outlined, the book summarises the basic theoretical tools, namely the time-independent and the time-dependent quantum mechanical approaches as well as the classical picture of photodissociation. The discussions of absorption spectra, diffuse vibrational structures, the vibrational and rotational state distributions of the photofragments form the core of the book. More specific topics such as the dissociation of vibrationally excited molecules, emission during dissociation, or nonadiabatic effects are also discussed. It will be of interest to graduate students and senior scientists working in molecular physics, spectroscopy, molecular collisions and molecular kinetics.