Physics of Ion Impact Phenomena

During the last ten years an unprecedented effort has been directed towards study of the dynamics of ion collision phenomena in the gas phase, usually with a view to applications in diverse areas, ranging from fusion reactors and lasers to ionospheric and interstellar chemistry and gaseous electronics. The principal aim of this volume is to present a succinct overview of contemporary interests and trends in the field of low energy ion-electron and ion-atom (molecule) collision physics, with emphasis on fundamental aspects. Researchers and students will become acquainted, in a general and fairly non-specialized fashion, with recent progress in this area of continuing intense activity. The material is divided into two parts, dealing with atomic ions and molecular ions. Each of the nine chapters has been prepared by authors who are amongst the most eminent practitioners of contemporary ion collision physics. The book is dedicated to Professor J.B. Hasted, one of the pioneering workers who, in the course of his forty year career, helped establish atomic collision physics as a field in its own right.

Inhalt

1. Introduction.- 1.1 The Need to Study Ion Impact Phenomena.- 1.2 Some Contemporary Ion Production Techniques.- 1.2.1 Electron Impact (EI) Sources.- 1.2.2 The Electron Bombardment Ion Source (EBIS).- 1.2.3 The Electron Cyclotron Resonance Ion Source (ECRIS).- 1.2.4 The 'Ion Hammer' Technique.- References.- 2. Ion Formation Processes: Ionization in Ion-Electron Collisions.- 2.1 Theoretical Methods.- 2.1.1 The Classical Approach of J. J. Thomson.- 2.1.2 Quantum Mechanical Approaches.- 2.1.3 Predictor Formulae.- 2.1.4 Threshold Behaviour.- 2.2 Ionization Mechanisms.- 2.2.1 Single Ionization.- 2.2.2 Multiple Ionization.- 2.2.3 Summation of Cross Section Contributions.- 2.3 Experimental Approaches.- 2.3.1 Plasma Rate Measurements.- 2.3.2 Trapped-Ion Methods.- 2.3.3 Ion Channeling.- 2.3.4 Crossed-Beams Method.- 2.4 Single Ionization Cross Section Data.- 2.4.1 Hydrogen-like Ions.- 2.4.2 Helium-like Ions.- 2.4.3 Lithium-like Ions.- 2.4.4 Sodium-like Ions.- 2.4.5 Heavy Alkali-like Ions.- 2.4.6 Magnesium-like Ions.- 2.4.7 Isonuclear Sequences.- 2.4.8 Ionization of Heavy Ions.- 2.5 Multiple Ionization Cross Section Data.- 2.5.1 Helium-like Ions.- 2.5.2 The Argon Isonuclear Sequence.- 2.5.3 The Xenon Isonuclear Sequence.- 2.6 A Unified Picture of Ionization.- 2.6.1 Single and Double Ionization of Sb and Bi Ions.- 2.6.2 Single and Multiple Ionization of Heavy Metal Ions.- 2.7 Conclusions.- References.- 3. Ion-Neutral Reactions: Collision Spectrometry of Multiply Charged Ions at Low Energies.- 3.1 Dynamics of Collisions.- 3.2 Theoretical Aspects.- 3.2.1 Landau-Zener Model.- 3.2.2 The Classical Over-Barrier Transition Model.- 3.2.3 Reaction Window.- 3.3 Experimental Techniques.- 3.4 Discussion of Translational Energy Spectrometry.- 3.4.1 State-Selective Single Electron Capture Processes by Ground and Metastable Doubly Charged Ions.- 3.4.2 State-Selective Single Electron Capture by Multiply Charged Ions.- 3.4.3 Multiple Electron Capture by Multiply Charged Ions.- 3.5 Discussion of State-Selective Differential Electron Capture Cross Sections.- References.- 4. Energy Spectrometry of Fine-Structure Transitions in Ion-Atom Collisions.- 4.1 High-Resolution Ion Translational Energy Spectrometry.- 4.1.1 Apparatus.- 4.1.2 Broadening of Line Shape.- 4.2 Fine-Structure Transitions in Ne+, Ar+ and Kr+.- 4.2.1 Translational Energy Spectra.- 4.2.2 Fractional Populations of 2P3/2 and 2P1/2 States.- 4.2.3 Cross Sections for Fine-Structure Transitions in Ne+, Ar+ and Kr+.- 4.3 Excitation and De-excitation Processes in Doubly Charged Rare Gas Ions.- 4.3.1 Translational Energy Spectra.- 4.3.2 Fractional Populations of 3PJ, 1D2 and 1S0.- 4.3.3 Cross Sections for Excitation and De-excitation Among 3P2, 3P1, 3Po, 1D2 and 1S0 States.- 4.4 The Role of Fine-Structure States in Electron Capture Reactions.- 4.4.1 Relative Cross Sections for Reactions in Kr2+(1D2)+Ne.- 4.4.2 Diabatic Potential Energy Curves.- 4.4.3 Landau-Zener Model for Single Crossing.- 4.4.4 Multichannel Landau-Zener Model.- 4.4.5 Landau-Zener Calculation with Weighted Transition Probability.- References.- 5. Probing Interaction Potentials: Small Angle Differential Scattering of H+ and H with He.- 5.1 Experimental Method.- 5.2 Theoretical Considerations.- 5.2.1 Molecular Orbital Expansion Method.- 5.2.2 Potential Scattering.- 5.3 Results and Discussion.- 5.3.1 H-He Direct Scattering.- 5.3.2 H+-He Charge Transfer and Direct Scattering.- 5.4 Summary.- References.- 6. High-Resolution Translational Energy Spectrometry of Molecular Ions.- 6.1 Some Typical Experimental Arrangements.- 6.1.1 Double-Focussing Arrangements.- 6.2 Results and Discussion.- 6.2.1 TES of keV Atomic Ions.- 6.2.2 TES and the Spin-Conservation Rule.- 6.2.3 Doubly Charged Diatomic Molecules.- References.- 7. Molecular Ionization Energies by Double Charge Transfer Spectrometry.- 7.1 Apparatus and Experimental Techniques.- 7.1.1 Double Charge Transfer Spectrometry Prior to 1977.- 7.1.2 Double Charge Transfer Spectrometer Used at Paris.- 7.1.3 Double Charge Transfer Spectrometry at Swansea.- 7.1.4 Double Charge Transfer Spectrometer Used at Bombay.- 7.2 Studies of Electronic States of Doubly Charged Ions.- 7.2.1 Spin Conservation.- 7.2.2 Studies of Small Molecules.- 7.3 Studies of Large Molecules.- 7.3.1 CH3OH.- 7.3.2 SF6.- 7.3.3 CH4.- 7.3.4 Fluoromethanes, Chloromethanes and Bromomethanes.- 7.3.5 Perhalomethanes.- 7.3.6 Fluoroethanes.- 7.4 Reaction Window for Double Electron Capture.- 7.4.1 Endoergicity of DEC Reactions.- 7.4.2 Theoretical Prediction of a Reaction Window.- 7.4.3 Relative Cross Sections for DEC Reactions Measured as a Function of Endoergicity.- 7.4.4 Evidence for a Reaction Window in Collisions Involving the Molecular Target CH3Br.- 7.5 Single Ionization Energies of Radical Species.- 7.5.1 CH3O and CH3S Radicals.- 7.5.2 Mercaptyl Radicals C2H5S and n-C3H7S.- 7.5.3 CF2C1 and CFC12 Radicals.- 7.5.4 The SF5 Radical.- References.- 8. Studies of Multiply Charged Molecules by Ion Collision Techniques and Ab Initio Theoretical Methods.- 8.1 Stability of Multiply Charged Molecular Ions.- 8.1.1 Potential Energy Functions.- 8.1.1 A Qualitative Molecular Orbital Picture of Stability.- 8.2 Contemporary Ion-Impact Methods of Studying Multiply Charged Molecules.- 8.2.1 Translational Energy Spectrometry.- 8.2.2 Transmission of Singly and Doubly Charged Ions Through Electrostatic and Magnetic Fields.- 8.2.3 Charge-Stripping Studies.- 8.2.4 Double Electron Capture.- 8.2.5 Dissociation Studies.- 8.2.6 Excitation (De-excitation) and Electron Capture Reactions.- 8.2.7 Studies Using Forward-Geometry Mass Spectrometers.- 8.2.8 Studies Using High-Energy Accelerators.- 8.2.9 Energy Calibration.- 8.3 Other Experimental Techniques.- 8.3.1 Auger Spectroscopy.- 8.3.2 Photoionization Methods.- 8.3.3 Optical Spectroscopy.- 8.3.4 Electron Impact Experiments.- 8.4 Theoretical Description of Molecular Ions.- 8.4.1 The Schrödinger Equation and the Born-Oppenheimer Approximation.- 8.4.2 Hartree-Fock Theory.- 8.4.3 Electron Correlation.- 8.4.4 Multiconfiguration SCF Method (MCSCF).- 8.4.5 Spin-Coupled Valence Bond Theory.- 8.5 A Glimpse into the Real World of Multiply Charged Molecules: Ambiguities and Controversies.- 8.5.1 Diatomic Ions.- 8.5.2 Triatomic Ions.- 8.5.3 Polyatomic Ions.- References.- 9. Dissociative Recombination in Ion-Electron Collisions: New Directions.- 9.1 New Developments in the Merged Beam Technique.- 9.2 Detection of Highly Excited States.- 9.3 Measurements of Branching Ratios.- 9.4 Recombination Studies at Storage Rings.- 9.5 Heavy Ions.- 9.6 Epilogue.- Ions Fare Ye Well.- References.