Scattering of Thermal Energy Atoms PDF Download

Author: Bene Poelsema
Publisher:
ISBN: 9783662150900
Category :
Languages : en
Pages : 120

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Author: Bene Poelsema
Publisher: Springer
ISBN: 3540459839
Category : Science
Languages : en
Pages : 115

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Book Description
A variety of novel applications for the investigation of disordered surfaces by beams of thermal energy atoms are discussed and illustrated by numerous examples. A straightforward semiclassical approach is introduced to yield a remarkably detailed insight into the lateral distributions of diffuse scatterers such as adsorbates, vacancies and atomic steps. The recent discovery that the long range Van der Waals force is the cause of the unusually large cross-sections for diffuse He-scattering on individual defects and impurities led the authors to propose a new methods of surface analysis. They introduce a semiclassical method, the overlap approach, to give a simple and detailed description of He-scattering from disordered surfaces. The method yields subtle, otherwise hardly obtainable information on the nature of interactions between diffuse scatterers. The authors address such questions as the lateral distribution of adsorbates, two-dimensional phase transitions, surface diffusions, and the morphology of growing or sputtered layers.

Author: Tomas Andersson
Publisher:
ISBN: 9789162849542
Category :
Languages : en
Pages : 70

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Gregory Glenn Bishop
Publisher:
ISBN:
Category : Crystals
Languages : en
Pages : 258

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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This research consists of an experimental study of the scattering of free atoms in high Rydberg states and their interaction with ground-state atomic and molecular targets. The highly excited Rydberg states, lying just below the ionization limit, describe a single weakly bound electron moving around a positive ion core. These states are characterized by large principal quantum numbers, long radiative lifetimes, and large cross sections for certain scattering processes. In the proposed investigations, differential cross sections will be measured for the deflection of high Rydberg atoms from an atomic beam. Preliminary scattering experiments, completed in the laboratory, have yielded cross sections which are virtually independent of the principal quantum number and in good agreement with calculations for deflection of the core ion alone. The deflection was also observed directly. If the momentum transfer takes place as an essentially free-ion process, then it is possible to obtain ion-scattering cross section from measurements with Rydberg atoms as projectiles. The presence of a distant valence electron provides a charge-neutralizing sheath surrounding the ion core, rendering its trajectory virtually unaffected by non-ionizing external fields. Since ion-beam scattering experiments have heretofore proven difficult at thermal energies, this research program seeks to develop and exploit a useful new method for the determination of velocity-resolved free-ion differential cross sections and the functional form of ion-atom and ion-molecule interaction potentials.

Author: Edward S. Gillman
Publisher:
ISBN:
Category : Alkali metal halides
Languages : en
Pages : 224

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Author: Nicholas R. Lewkow
Publisher: Springer
ISBN: 3319250795
Category : Science
Languages : en
Pages : 115

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This thesis considers the non-equilibrium and energy transfer processes involved in the evolution of astrophysical gases and plasmas. Momentum-energy transfer in collisions of atoms, molecules and ions governs the evolution of interacting astrophysical gas and plasmas. These collisions require an accurate quantum mechanical description and the work presented here develops a unified kinetic and quantum-mechanical model for this consideration. The multi-scale computational approach implemented here takes into account non-thermal distributions of atomic particles and clarifies their role in the evolution of interstellar gas and planetary atmospheres. As shown, the physical parameters of non-thermal distributions strongly depend on the differential cross sections of atomic, molecular and ion collisions. Readers will find a detailed description of the energy relaxation of energetic atoms, produced in the interstellar gas by the solar and stellar wind plasmas. Computation of the non-thermal diffuse background of energetic helium atoms in the heliosphere is also included for evaluation of the contributions from local and cosmic sources and analysis of related satellite observations. Work involving modeling of energetic particle precipitation into planetary atmospheres and formation of the planetary and exoplanetary escape fluxes has been performed with very accurate cross sections, describing momentum-energy transfer processes with high precision. Results of the Monte Carlo simulations, carried out for the Mars atmosphere at different solar conditions, can be used for analysis of observational data for Mars atmospheric escape and investigation into the history of Martian water.

Author: Luiz Felipe Canto
Publisher: World Scientific
ISBN: 9814329843
Category : Science
Languages : en
Pages : 646

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The aim of the book is to give a coherent and comprehensive account of quantum scattering theory with applications to atomic, molecular and nuclear systems. The motivation for this is to supply the necessary theoretical tools to calculate scattering observables of these many-body systems. Concepts which are seemingly different for atomic/molecular scattering from those of nuclear systems, are shown to be the same once physical units such as energy and length are diligently clarified. Many-body resonances excited in nuclear systems are the same as those in atomic systems and come under the name of Feshbach resonances. We also lean heavily on semi-classical methods to explain the physics of quantum scattering OCo especially the interference seen in the angle dependence of the cross section. Having in mind a wide readership, the book includes sections on scattering in two dimensions which is of use in surface physics. Several problems are also included at the end of each of the chapters.

Author: Colm T. Whelan
Publisher: Springer Science & Business Media
ISBN: 0387275673
Category : Science
Languages : en
Pages : 342

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There is a unity to physics; it is a discipline which provides the most fundamental understanding of the dynamics of matter and energy. To understand anything about a physical system you have to interact with it and one of the best ways to learn something is to use electrons as probes. This book is the result of a meeting, which took place in Magdalene College Cambridge in December 2001. Atomic, nuclear, cluster, soHd state, chemical and even bio- physicists got together to consider scattering electrons to explore matter in all its forms. Theory and experiment were represented in about equal measure. It was meeting marked by the most lively of discussions and the free exchange of ideas. We all learnt a lot. The Editors are grateful to EPSRC through its Collaborative Computational Project program (CCP2), lOPP, the Division of Atomic, Molecular, Optical and Plasma Physics (DAMOPP) and the Atomic Molecular Interactions group (AMIG) of the Institute of Physics for financial support. The smooth running of the meeting was enormously facilitated by the efficiency and helpfulness of the staff of Magdalene College, for which we are extremely grateful. This meeting marked the end for one of us (CTW) of a ten-year period as a fellow of the College and he would like to take this opportunity to thank the fellows and staff for the privilege of working with them.