This volume contains the invited papers and selected contributed papers presented at the International Symposium on 'Electron-Molecule Scattering and Photoionization' held at SERC's Daresbury Laboratory, Cheshire, England from 18th to 19th ...

Author: P.G. Burke

Publisher: Springer

ISBN: 1461283094

Category: Science

Page: 272

View: 103

This volume contains the invited papers and selected contributed papers presented at the International Symposium on 'Electron-Molecule Scattering and Photoionization' held at SERC's Daresbury Laboratory, Cheshire, England from 18th to 19th July, 1987. This Symposium was a Satellite Meeting to the XVth International Conference on the Physics of Electronic and Atomic Collisions (ICPEAC I and follows a tradition of Satellite Meetings i. n related areas of collisions held in association with previous ICPEAC's. In order to make this volume as representative of the Symposium as possible 'Hot Topics' presented orally at the meeting together with a few papers selected by the Programme Committee from the contributed posters are included. The Editors are grateful to the authors for responding rapidly to the invitation to submit their contri butions for inclusion in the volume, as indeed they are grateful to all the authors for the high quality of their contributions. The Symposium brought together over 100 scientists from many countries and from broad interdisciplinary backgrounds to hear about current rapid advances in electron-molecule scatteri. ng and photoioniza tion. These advances have been stimulated on the experimental side by the increasing availability of electron beams with millivolt energy resolution, by synchrotron radiation sources and by intense tunable lasers. On the theoretical side the introduction of new computational methods enables accurate predictions to be made, resulting in a new and deeper understanding of the basic physical processes involved.

The development of reliable theoretical models for calculating the decay of quasi-stationary states of molecular systems has become an important endeavor for theoretical chemists.

Author:

Publisher:

ISBN: OCLC:893853296

Category:

Page:

View: 547

The development of reliable theoretical models for calculating the decay of quasi-stationary states of molecular systems has become an important endeavor for theoretical chemists. The understanding and analysis of a wide variety of physical and chemical phenomena depend on a knowledge of the behavior of these states in both collisional and photoionization problems. In this article we describe the theory and calculation of these cross sections using our Linear Algebraic/Optical Potential method. The theory makes optimal use of the numerical methods developed to solve large sets of coupled integral equations and the bound state techniques used by quantum chemists. Calculations are presented for a representative class of diatomic and triatomic molecules at varying levels of sophistication and for collisional and photoionization cross sections. 48 references, 11 figures.

We approach this subject in two steps. First, we very briefly outline the well-established connections, e.g., the Bethe-Born theory and comparisons of isoelectronic systems.

Author:

Publisher:

ISBN: OCLC:727286222

Category:

Page:

View: 253

Most of our detailed information on the spectroscopy and dynamics of the electronic continuum of molecules is based on the complementary probes - photoionization and electron scattering. Though usually studied separately, it is most useful to appreciate the connections between these two processes since our understanding of one is often the key to interpreting or even generating new results in the other. We approach this subject in two steps. First, we very briefly outline the well-established connections, e.g., the Bethe-Born theory and comparisons of isoelectronic systems. Then we focus on a point of contact - the role of shape resonances in molecular photoionization and electron-molecule scattering - for which a substantial amount of new information has become available. Specific topics include mapping of resonances from the neutral (h.nu. + molecule) to the negative ion (e + molecule) system, angular distributions, and interaction with vibration.

Library of Congress Cataloging in Publication Data International Symposium on Electron–Molecule Scattering and Photoionization (1987: Daresbury Laboratory) ...

Author: P.G. Burke

Publisher: Springer Science & Business Media

ISBN: 9781461310495

Category: Science

Page: 272

View: 905

This volume contains the invited papers and selected contributed papers presented at the International Symposium on 'Electron-Molecule Scattering and Photoionization' held at SERC's Daresbury Laboratory, Cheshire, England from 18th to 19th July, 1987. This Symposium was a Satellite Meeting to the XVth International Conference on the Physics of Electronic and Atomic Collisions (ICPEAC I and follows a tradition of Satellite Meetings i. n related areas of collisions held in association with previous ICPEAC's. In order to make this volume as representative of the Symposium as possible 'Hot Topics' presented orally at the meeting together with a few papers selected by the Programme Committee from the contributed posters are included. The Editors are grateful to the authors for responding rapidly to the invitation to submit their contri butions for inclusion in the volume, as indeed they are grateful to all the authors for the high quality of their contributions. The Symposium brought together over 100 scientists from many countries and from broad interdisciplinary backgrounds to hear about current rapid advances in electron-molecule scatteri. ng and photoioniza tion. These advances have been stimulated on the experimental side by the increasing availability of electron beams with millivolt energy resolution, by synchrotron radiation sources and by intense tunable lasers. On the theoretical side the introduction of new computational methods enables accurate predictions to be made, resulting in a new and deeper understanding of the basic physical processes involved.

In this volume, are collected the contributions of the invited speakers, as well as the roundtable and evening discussions condensed from taped recordings of the entire proceedings.

Author: T.N. Rescigno

Publisher: Springer Science & Business Media

ISBN: 9781468469882

Category: Technology & Engineering

Page: 355

View: 236

The First Asilomar Conference on Electron- and Photon-Molecule Collisions was held August 1-4, 1978 in Pacific Grove, California. This meeting brought together forty scientists who are actively involved in theoretical studies of electron scattering by, and photoionization of, small molecules. In this volume, are collected the contributions of the invited speakers, as well as the roundtable and evening discussions condensed from taped recordings of the entire proceedings. The subject matter reflects current activity in the field and describes many of the techniques that are being developed and applied to molecular collision problems. We would like to thank the Air Force Office of Scientific Research (AFOSR) and the Office of Naval Research (ONR) for providing the financial support that made this conference possible. Special thanks are due to Dr. Robert Junker of ONR and Dr. Ralph Kelley of AFOSR for the interest and encouragement they provided in all phases of this meeting. We also thank all the participants whose efforts and contributions made this conference a success. Finally, we thank Ms. Charlotte MacNaughton and Ms. Sara Jackson for the many hours they spent transcribing tapes and preparing this volume for publication.

In electron scattering, it enhances vibrational excitation. Recent work is reviewed in which new, observable manifestations of this coupling were predicted theoretically and then verified experimentally. 67 references.

Author:

Publisher:

ISBN: OCLC:1061353375

Category:

Page:

View: 493

Shape resonances in the electronic continuum of molecules induce strong coupling between vibrational and electronic motion over a spectral range much broader than the resonance half width. In photoionization, this coupling causes large deviations from Franck-Condon intensity distributions and strong dependence of photoelectron angular distributions on the vibrational state of the residual ion. In electron scattering, it enhances vibrational excitation. Recent work is reviewed in which new, observable manifestations of this coupling were predicted theoretically and then verified experimentally. 67 references.

Volume 54 of the Advances in Atomic, Molecular, and Optical Physics Series contains ten contributions, covering a diversity of subject areas in atomic, molecular and optical physics.

Author:

Publisher: Elsevier

ISBN: 0080467377

Category: Science

Page: 748

View: 254

Volume 54 of the Advances in Atomic, Molecular, and Optical Physics Series contains ten contributions, covering a diversity of subject areas in atomic, molecular and optical physics. The article by Regal and Jin reviews the properties of a Fermi degenerate gas of cold potassium atoms in the crossover regime between the Bose-Einstein condensation of molecules and the condensation of fermionic atom pairs. The transition between the two regions can be probed by varying an external magnetic field. Sherson, Julsgaard and Polzik explore the manner in which light and atoms can be entangled, with applications to quantum information processing and communication. They report on the result of recent experiments involving the entanglement of distant objects and quantum memory of light. Recent developments in cold Rydberg atom physics are reviewed in the article by Choi, Kaufmann, Cubel-Liebisch, Reinhard, and Raithel. Fascinating experiments are described in which cold, highly excited atoms (“Rydberg atoms) and cold plasmas are generated. Evidence for a collective excitation of Rydberg matter is also presented. Griffiin and Pindzola offer an account of non-perturbative quantal methods for electron-atom scattering processes. Included in the discussion are the R-matrix with pseudo-states method and the time-dependent close-coupling method. An extensive review of the R-matrix theory of atomic, molecular, and optical processes is given by Burke, Noble, and Burke. They present a systematic development of the R-matrix method and its applications to various processes such as electron-atom scattering, atomic photoionization, electron-molecule scattering, positron-atom scattering, and atomic/molecular multiphoton processes. Electron impact excitation of rare-gas atoms from both their ground and metastable states is discussed in the article by Boffard, Jung, Anderson, and Lin. Excitation cross sections measured by the optical method are reviewed with emphasis on the physical interpretation in terms of electronic structure of the target atoms. Ozier and Moazzen-Ahmadi explore internal rotation of symmetric top molecules. Developments of new experimental methods based on high-resolution torsional, vibrational, and molecular beam spectroscopy allow accurate determination of internal barriers for these symmetric molecules. The subject of attosecond and angstrom science is reviewed by Niikura and Corkum. The underlying physical mechanisms allowing one to generate attosecond radiation pulses are described and the technology needed for the preparation of such pulses is discussed. LeGouët, Bretenaker, and Lorgeré describe how rare earth ions embedded in crystals can be used for processing optically carried broadband radio-frequency signals. Methods for reaching tens of gigahertz instantaneous bandwidth with submegahertz resolution using such devices are analyzed in detail and demonstrated experimentally. Finally, in the article by Illing, Gauthier, and Roy, it is shown that small perturbations applied to optical systems can be used to suppress or control optical chaos, spatio-temporal dynamics, and patterns. Applications of these techniques to communications, laser stabilization, and improving the sensitivity of low-light optical switches are explored. International experts Comprehensive articles New developments

The role of nonadiabatic interaction is raised here. When the final vibrational state is in the continuum, molecular dissociation occurs. Dissociative recombination and dissociative attachment are examples of such fragmentation processes.

Author: Franco A. Gianturco

Publisher: Springer Science & Business Media

ISBN: 9781475797978

Category: Science

Page: 364

View: 589

The collision of electrons with molecules and molecular ions is a fundamental pro cess in atomic and molecular physics and in chemistry. At high incident electron en ergies, electron-molecule collisions are used to deduce molecular geometries, oscillator strengths for optically allowed transitions, and in the case of electron-impact ionization, to probe the momentum distribution of the molecule itself. When the incident electron energy is comparable to or below those of the molecular valence electrons, the physics involved is particularly rich. Correlation and exchange effects necessary to describe such collision processes bear a close resemblance to similar efft:cts in the theory of electronic structure in molecules. Compound state formations, in the form of resonances and vir tual states, manifest themselves in experimental observables which provide details of the electron-molecule interactions. Ro-vibrational excitations by low-energy electron collisions exemplify energy transfer between the electronic and nuclear motion. The role of nonadiabatic interaction is raised here. When the final vibrational state is in the continuum, molecular dissociation occurs. Dissociative recombination and dissociative attachment are examples of such fragmentation processes. In addition to its fundamental nature, the study of electron-molecule collisions is also motivated by its relation to other fields of study and by its technological appli cations. The study of planetary atmospheres and the interstellar medium necessarily involve collision processes of electrons with molecules and molecular ions.

Now let us turn to the extension of the formalism to molecular photoionization . Photoionization . The photoionization process , AB + hv + AB + + e ( 23 ) ...

These processes now include: electron atom and electron ion scattering [5j; atomic polarisabilities [6]; atomic and molecular photoionisation processes (7 ...

Author: T-N Chang

Publisher: World Scientific

ISBN: 9789814505772

Category: Science

Page: 420

View: 979

Detailed discussions on many of the recent advances in the many-body theory of atomic structure are presented by the leading experts around the world on their respective specialized approaches. Emphasis is given to the photoionization dominated by the resonance structures, which reveals the effect of the multi-electron interaction in atomic transitions involving highly correlated atomic systems. Recent experimental developments, stimulated by the more advanced applications of intense lasers and short wavelength synchrotron radiation, are also reviewed. This book brings together a comprehensive theoretical and experimental survey of the current understanding of the basic physical processes involved in atomic processes. Contents:Recent Many-Body Perturbation Calculations of Photoionization Cross Sections (H P Kelly)Relativistic Many-Body Theory Applied to Highly-Charged Ions (W R Johnson)R-Matrix Theory of Atomic and Molecular Processes (P G Burke)Precision Configuration-Interaction Calculation for Atomic Systems with an 1s2-Core (K T Chung)Hyperspherical Coordinate Description of Single- and Multiphoton Processes in Two-Electron Systems (A F Starace)Non-Variational Multiconfiguration Hartree-Fock Calculations for Continuum Wave Functions (C F Fischer)L2 Basis Function Methods for the Electronic Continuum. Photoionization and Some Related Processes (V Carravetta et al.)B-Spline Based Configuration-Interaction Approach for Photoionization of Two-Electron and Divalent Atoms (T-N Chang)Many-Electron Effects on Auger Transitions (M H Chen)Multiple Excitation Processes in Photoionization (J A R Samson)Atomic Structure Effects in Multiphoton Processes: An Experimental Perspective (L F DiMauro)Many-Body Interactions in Photoionization of Excited Atoms and Ions (F J Wuilleumier)and other papers Readership: Atomic physicists or graduate students (MS level or above). keywords:Photoionization;Many-Body Theory;Many-Body Effects;Atomic Structure;Photoabsorption;Configuration Interaction;Multiple Excitation;Autoionization;Doubly Excited Resonance;Multiphoton Processes

The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, ...

Author: Hans Kleinpoppen

Publisher: Springer Science & Business Media

ISBN: 9783642405143

Category: Science

Page: 340

View: 967

The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or `complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment `complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The `complete' experiment is, until today, hardly to perform. Therefore, much attention is paid to the results of state-of-the-art experiments providing detailed information on the process, and their comparison to the related theoretical approaches, just to mention relativistic multi-configurational Dirac-Fock, convergent close-coupling, Breit-Pauli R-matrix, or relativistic distorted wave approaches, as well as Green's operator methods. This book has been written in honor of Herbert Walther and his major contribution to the field but even to stimulate advanced Bachelor and Master students by demonstrating that obviously nowadays atomic and molecular scattering physics yields and gives a much exciting appreciation for further advancing the field.

Full text: Shape resonances have begun to play a central role in the study of spectroscopy and dynamics of molecular photoionization.

Author:

Publisher:

ISBN: OCLC:1066573009

Category:

Page: 55

View: 141

Full text: Shape resonances have begun to play a central role in the study of spectroscopy and dynamics of molecular photoionization. They manifest themselves as bands of enhanced absorption in the spectra of most (nonhydride) molecules and often stand out prominently against a nonresonant background. These resonances arise from centrifugal barriers in the molecular potential experienced by the escaping photoelectron, and their gross features can be described in terms of simple barrier-penetration concepts. Using both experimental data and recent theoretical calculations, we survey the properties (e.g., symmetry, spatial distribution, and dominant partial waves) of several molecular shape resonances and show how this information relates to the analysis of wavelength-dependent photoelectron spectra, photoelectron angular distributions, and photoabsorption spectra of molecules in different physical states. Special emphasis will be given to the correspondence between resonances in molecular photoionization and electron-molecule scattering.

Adapting gas-phase electron scattering R-matrix calculations to a condensed-matter ... Electron-molecule scattering and molecular photoionization using the ...

Author: Petr Carsky

Publisher: CRC Press

ISBN: 9781439839119

Category: Science

Page: 296

View: 112

Since the turn of the 21st century, the field of electron molecule collisions has undergone a renaissance. The importance of such collisions in applications from radiation chemistry to astrochemistry has flowered, and their role in industrial processes such as plasma technology and lighting are vital to the advancement of next generation devices. Furthermore, the development of the scanning tunneling microscope highlights the role of such collisions in the condensed phase, in surface processing, and in the development of nanotechnology. Low-Energy Electron Scattering from Molecules, Biomolecules and Surfaces highlights recent progress in the theory and experiment of electron-molecule collisions, providing a detailed review of the current state of knowledge of electron molecule scattering—theoretical and experimental—for the general physicist and chemist interested in solving practical problems. In few other branches of science is the collaboration between theorists and experimentalists so topical. Covering advancements in practical problems, such as those met in plasma physics, microelectronics, nanolithography, DNA research, atmospheric chemistry, and astrochemistry, this book describes the formal general scattering theory and description of the experimental setup at a level the interested non-expert can appreciate.

Author: Antonio Carlos Fontes dos SantosPublish On: 2018-10-03

This volume describes the advanced research on the behavior of electrons in ionized atoms and molecules. Readers will learn about relevant techniques used and experimental results for different electron and molecular theories.

Author: Antonio Carlos Fontes dos Santos

Publisher: Bentham Science Publishers

ISBN: 9781681086132

Category: Science

Page: 242

View: 427

This volume describes the advanced research on the behavior of electrons in ionized atoms and molecules. Readers will learn about relevant techniques used and experimental results for different electron and molecular theories. The information presented in the book is useful for scholars and researchers involved in nuclear and atomic physics programs. Topics covered in the volume include: -Ionization experiments -Kinetic energy studies of photoexcited carbon dichloride and tetrachloride molecules -Selective excision of biomolecules in electron transfer experiments -Particle and antiparticle collisions with rare gases -Multiple scattering in electron Rutherford scattering spectroscopy -Four-body effects in the 6He58 +58Ni scattering -Twin atoms from doubly excited states of the hydrogen molecule.