Photophysics and Photochemistry in the Vacuum Ultraviolet

This volume contains the texts of the Invited Lectures pre­ sented at the NATO Advanced Study Institute PHOTOPHYSICS AND PHOTOCHEMISTRY IN THE VACUUM ULTRAVIOLET, which was held at the Interlaken Lodge in Lake Geneva, Wisconsin USA, August 15-28, 1982. This ASI was the third in a series of NATO Institutes de­ voted to a study of the physical and chemical transformations undergone by atoms and molecules after absorption of high-energy (VUV < 6 eV) radiation. [The previous Institutes were CHEMICAL SPECTROSCOPY AND PHOTOCHEMISTRY IN THE VACUUM ULTRAVIOLET (Val Morin, Canada, 1973) and HIGH-ENERGY CHEMICAL SPECTROSCOPY AND PHOTOCHEMISTRY (Breukelen, The Netherlands, 1976). ] The purpose of this ASI was to provide a forum for the ex­ change of attitudes and viewpoints between physicists and chem­ ists working in the VUV area. This area represents one of the most fertile regions for chemistry/physics interfacing, yet the chemists remain largely unaware of the fact that the physicists have implicitly solved many of the chemists' problems (and vice versa); and the physicists remain largely unaware of the nature of the chemists' problems (and vice versa). Consequently, a major aim of the Institute was to construct a proper Chemistry/ Physics Interface, to familiarize each group with the techniques, both experimental and theoretical, of the other group, and to bring the major successes and failures of each group, within the VUV area, to light. The above stipUlations concerning the Institute also serve as desiderata for the present volume.

Contenu

Photophysics of Highly-Excited States.- 1. Introduction.- 2. Quantum Defect Theory.- 3. Core Effects.- 4. Intermolecular Rydberg Correlations.- 5. Field Effects.- 6. Rydberg States in Condensed Media.- 7. Concluding Remarks.- Methods for Studying Higher Excited States in Molecules and Molecular Crystals by Means of Synchrotron Radiation.- 1. Introduction.- 2. Properties of Synchrotron Radiation Sources: A Short Overview.- 3. Some General Aspects of Synchrotron Radiation Instrumentation.- 4. Absorption and Reflection Spectroscopy.- 5. Time-Resolved and Energy-Resolved VUV Luminescence Spectroscopy.- 6. Photoemission.- 7. Perspectives.- 8. Appendix.- Nonlinear Optics and Laser Spectroscopy in the Vacuum Ultraviolet.- 1. Introduction.- 2. Vacuum Ultraviolet Lasers.- 3. Nonlinear Optical Methods for Producing Tunable VUV Radiation.- 4. Applications to Chemical Physics.- 5. Future Goals.- Multiphoton Ionization and Third-Harmonic Generation in Atoms and Molecules.- 1. Introduction.- 2. Resonantly-Enhanced Multiphoton Ionization.- 3. Multiphoton Ionization and Third-Harmonic Generation in Rare Gases.- Electron-Impact Spectroscopy of Molecules.- 1. Introduction.- 2. General Theory.- 3. Experimental.- 4. Experimental Results.- Elements of Quantum Defect Theory. I. Introduction and Formalism.- 1. Introduction to Quantum Defect Theory.- 2. Multichannel Quantum Defect Theory in Atoms.- Elements of Quantum Defect Theory. II. A Unified Theory of Rydberg and Autoionizing States.- 1. Introduction.- 2. Eigenchannel Quantum Defect Theory.- 3. Ab initio Calculations of Quantum Defect Parameters.- 4. Applications.- Elements of Quantum Defect Theory. III. Diatomic Molecules.- 1. Introduction to Molecular QDT.- 2. Comparison with Experiment.- 3. Inclusion of Molecular Dissociation.- Negative-Ion States.- 1. Introduction.- 2. Negative-Ion Properties.- 3. Unimolecular Electron Attachment.- 4. Multiply-Charged Negative Ions.- 5. Photoabsorption by Negative Ions.- 6. Recent Studies of Long-Lived He Negative Ions.- 7. Production of Negative Ions by Photon Reactions.- 8. Collision of High-Rydberg Atoms with Electron-Attaching Molecules and the Possible Influence of Dipole Bound States.- 9. Negative Ions of Molecular Clusters.- Superexcited nd Ionic State Relaxation Processes in Vacuum Ultraviolet Excited Polyatomic Molecules.- 1. Introduction.- 2. Fundamental Processes.- 3. Competing Decay Channels of Superexcited States.- 4. Methods for Studying Superexcited and Ionic States and Their Relaxation Processes.- 5. Further Remarks on Molecular Autoionization.- 6. Decay of Ion States.- Photoionization Dynamics of Small Molecules.- 1. Introduction.- 2. Shape Resonances in Molecular Photoionization.- 3. Molecular Autoionization.- 4. Concluding Remarks.- Photodissociation Dynamics of Gas-Phase Small Molecules.- 1. Introduction.- 2. ICN Photodissociation in the Near Ultraviolet.- 3. VUV Photodissociation of HCN.- 4. VUV Photodissociation of the Cyanogen Halides.- 5. Conclusions.- VUV Spectroscopy of Rare-Gas Van Der Waals Dimers.- 1. Introduction.- 2. General Background.- 3. Experimental Apparatus.- 4. Dependence of the Cluster Ion Signals on Nozzle Stagnation Pressure.- 5. Appearance Potentials of the Dimer Ions and Dissociation Energies of the Dimer-Ion Ground States.- 6. Molecular Rydberg Structure Between the Atomic Fine-Structure Thresholds: Dissociation Energies of X+2(C 2?1/2u) and XY+(B 2?1/2 and D 2?1/2+).- 7. Molecular Rydberg Structure in the Spectra of NeY Near the Ne 3s Atomic Resonance.- 8. Molecular Rydberg Structure in the Spectra of ArKr and ArXe Near the Ar 5s and 3d Atomic Resonances.- 9. Molecular Rydberg Structure in the Spectra of X2 and XY Near the High-Lying Atomic Rydberg States.- 10. Summary and Conclusions.- Excitons and Energy Transfer in Insulators.- 1. Prologue.- 2. Frenkel Excitons.- 3. Wannier Excitons.- 4. Deep Wannier Atomic Impurity States.- 5. Excitons and Impurity States in Rare-Gas Fluids.- 6. Molecular Wannier Impurity States in Rare-Gas Solids.- 7. Excited-State Dynamics in Rare-Gas Solids.- 8. Self-Trapping of Excitons in Rare-Gas Solids.- 9. Lattice Relaxation Around Impurity States.- 10. Electronic Relaxation of Impurity States.- 11. Electronic Energy Transfer in Rare-Gas Solids.- 12. Perspectives.- Regular and Irregular Motion in Classical and Quantum Systems.- 1. Introduction: Order and Chaos.- 2. Integrable Systems.- 3. Perturbation of Integrable Systems and the KAM-Theorem.- 4. Area-Preserving Mappings.- 5. Chaotic Systems.- 6. A Generic System is Neither Integrable Nor Ergodic, But Shows a Stochastic Transition.- 7. The Birkhoff-Gustavson Normal Form and Invariant Tori Below the Critical Energy.- 8. Do Quantum Systems Exhibit Chaotic Behavior?.- 9. Integrable Systems and Tori Quantization.- 10. Quantization of Chaotic Systems.- 11. Statistics of Energy Levels.- 12. Quantizing a Generic System.- 13. Conclusions and Discussion.- New Trends in Atomic Diamagnetism.- 1. Introduction.- 2. The Coulomb Spectrum.- 3. The Landau Spectrum.- 4. The Atom in a Magnetic Field.- 5. Classical Mechanics of Diamagnetism.- 6. Quantum Mechanical Approach.- 7. Semi-Classical Methods.- 8. Experimental Studies in Atomic Physics.- 9. Prospects and Conclusions.- Evidence for Motional Electric Field Effects in the Absorption Spectrum of Lithium Vapor in a Magnetic Field.- 1. Introduction.- 2. Results and Discussion.- On the Spectrum Of V(?) $$V\left( \rho \right) = - \frac{{qt}}{\rho } + \frac{{rt}}{{{\rho ^2}}} + stp + t{p^2}.$$. Physical Implications for a Variety of Problems.- 1. Introduction.- 2. Solution of the Eigenvalue Problem.- 3. Applications.- 4. Summary.- Perturbation Spectroscopy.- 1. Introduction.- 2. Perturbation Theory and MCD Spectroscopy.- 3. Electric Field-Effect Spectroscopy.- 4. Pressure-Effect Spectroscopy.- Circular Dichroism and Magnetic Circular Dichroism Studies in the Vacuum Ultraviolet.- 1. Introduction.- 2. Instrumentation.- 3. Results.- Electric Field Studies in the Vacuum Ultraviolet.- 1. Introduction.- 2. Experimental.- 3. General Results.- 4. Excited-State Parameters.- 5. Arc-Suppressor "Solvent" Effects.- 6. Conclusions.- Valence-Shell and Rydberg Transitions in Large Molecules.- 1. Introduction.- 2. The Rydberg Concept.- 3. From Spectra to Photochemistry.- 4. Rydberg States of Transition Metal Complexes.- Multiphoton Spectroscopy and Photochemistry.- 1. Introduction.- 2. Nonlinear P…