Progress in Atomic Spectroscopy Parte
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Progress in Atomic Spectroscopy
Parte
PHYSICS OF ATOMS AND MOLECULES
Series Editors P. G. Burke, The Queen's University of Belfast, Northern Ireland
H. K1einpoppen, Atomic Physics Laboratory, University of Stirling, Selotland
R. B. Bernstein (New York, U.S.A.) J. C. Cohen-Tannoudji (Paris, France) R. W. Crompton (Canberra, Australia)
J. N. Dodd (Dunedin, New Zealand) G. F. Drukarev (Leningrad, U.S.S.R.)
W. Hanle (Giessen, Germany)
Editorial Advisory Board
C. J. Joachain (Brussels, Belgium) W. E. Lamb, Jr. (Tucson, U.S.A.) P.·O. LOwdin (Gainesville, U.S.A.)
H. O. Lutz (Bielefeld, Germany) M. R. C. McDowell (London, U.K.)
K. Takayanagi (Tokyo, Japan)
ELECTRON AND PHOTON INTERACTIONS WITH ATOMS Edited by H. K1einpoppen and M. R. C. McDowell
PROGRESS IN ATOMIC SPECTROSCOPY, Parts A and B Edited by W. Hanle and H. K1einpoppen
ATOM-MOLECULE COLLISION THEORY: A Guide for the Experimentalist Edited by Richard B. Bernstein
COHERENCE AND CORRELATION IN ATOMIC COLLISIONS Edited by H. K1einpoppen and J. F. Williams
VARIATIONAL METHODS IN ELECTRON-ATOM SCATIERING THEORY R. K. Nesbet
DENSITY MATRIX THEORY AND APPLICATIONS Karl Blum
INNER·SHELL AND X·RAY PHYSICS OF ATOMS AND SOLIDS Edited by Derek J. Fabian, Hans Kleinpoppen, and Lewis M. Watson
INTRODUCTION TO THE THEORY OF LASER-ATOM INTERACTIONS Marvin H. Mittleman
ATOMS IN ASTROPHYSICS Edited by P. G. Burke, W. B. Eissner, D. G. Hummer, and I. C. Percival
ELECTRON-ATOM AND ELECTRON-MOLECULE COLLISIONS Edited by Juergen Hinze
PROGRESS IN ATOMIC SPECTROSCOPY, Part C Edited by H. J. Beyer and Hans K1einpoppen
A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher.
Progress in Atomic Spectroscopy
Parte
Edited by
HJ Beyer and
Hans Kleinpoppen University of Stirling
Stirling. United Kingdom
Springer Science+ Business Media, LLC
Library of Congress Cataloging in Publication Data
Main entry under title:
Progress in atomic spectroscopy.
(Physics of atoms and molecules.) Part C- edited by H. J. Beyer and Hans Kleinpoppen. Includes bibliographical references and indexes. 1. Atomic spectra. I. Hanle, Wilhelm, 1901- . II. Kleinpoppen, Hans. III.
Beyer, H. J. QC454.A8P76 1983 539.7 78-18230
ISBN 978-1-4612-9651-5 ISBN 978-1-4613-2647-2 (eBook) DOI 10.1007/978-1-4613-2647-2
© 1984 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1984
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
To Wilhelm Haole
Professor Wilhelm Haole
Contents of Part C
Contents of Part A Contents of Part B ........... . Introduction by H. 1. Beyer and H. Kleinpoppen
Chapter 1
The k Ordering of Atomic Structure R. M. Sternheimer
xv xxiii xxxi
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. The Limiting Ionicity 8) and the Limiting Angular Momentum I) . . . . . . 5 3. The k Ordering of Atomic Energy Levels and its Relation to the Fine-Structure
Inversion in Atomic and Ionic Spectra ................. 10 4. The k Ordering of Atomic Energy Levels and its Relation to the Spectroscopic
Quantum Defects .......... 15 5. k-Symmetry Breaking in Atomic Spectra 20 6. Conclusions 23
References and Notes 26
Chapter 2
Multiconfiguration Hartree-Fock Calculations for Complex Atoms Charlotte Froese Fischer
1. Introduction . . . . . 1.1. The Hartree-Fock Approximation 1.2. Brillouin's Theorem ..... . 1.3. LS Dependence . . . . . .
2. Correlation and the MCHF Approximation 2.1. The MCHF Method ...... . 2.2. Zero- and First-Order Sets 2.3. Brillouin's Theorem and Interaction with Series 2.4. Unconstrained Orbitals 2.5. Reduced Forms
3. Excited States 4. Transition Metals 5. Relativistic Corrections
vii
29 29 30 31 32 33 33 34 36 37 39 40 44
viii Contents of Part C
6. Transition Probabilities . . . . . . . . . . . . 6.1. A First-Order Theory for Oscillator Strengths 6.2. Core Polarization and Ionization Energies 6.3. f Value Trends 6.4. Relativistic Effects References . . . . . .
Chapter 3
New Methods in High-Resolution Laser Spectroscopy B. Couillaud and A. Ducasse
48 48 49 51 54 55
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 57 2. New Sources in High-Resolution Spectroscopy and Their Frequency
Calibration ...... 59 2.1. The Ring Laser 59 2.2. Mode-Locked Lasers 63 2.3. Color Center Lasers 65 2.4. Precise Wavelength Calibration for Tunable Lasers 68
3. Frequency Doubling and Sum Frequency Mixing for High-Resolution Spectroscopy in the Near uv . . . . . . 72 3.1. Second-Harmonic Generation (SHG) . . . . . . . . . . . . 74 3.2. Sum Frequency Mixing (SFM) . . . . . . . . . . . . . . . 79
4. New High-Resolution Spectroscopy Techniques Using Single-Mode Lasers 82 4.1. New Techniques Improving the Resolution 83 4.2. New Techniques Improving the Sensitivity ....... 93
5. High-Resolution Spectroscopy with Short Light Pulses 101 5.1. Quantum Interference Effects in Two-Photon Spectroscopy 102 5.2. Saturated Absorption and Polarization Spectroscopy with a Coherent
Train of Short Light Pulses 108 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Chapter 4
Resonance Ionization Spectroscopy: Inert Atom Detection C. H. Chen, G. S. Hurst, and M. G. Payne
1. Introduction . . . . . . . . . . . . . . . . . . . . 2. Resonance Ionization Spectroscopy . . . . . . . . . . 3. RIS on Rare Gas Atoms, Including Various Laser Schemes
3.1. Introduction . . . . . . . . . . . . . . . . . . 3.2. Two-Photon Excitation of Inert Gases with Broad Bandwidth Lasers 3.3. RIS Schemes for Ar, Kr, and Xe 3.4. Effective Volume for Ionization
4. RIS Experiments with Xe Atoms . . 5. On the Realization of Maxwell's Sorting Demon 6. Applications . . . . . .
6.1. Baryon Conservation 6.2. Solar Neutrino Flux 6.3. (3-(3- Decay 6.4. Oceanic Circulation
115 116 121 121 121 125 128 132 138 143 143 144 145 146
Contents of Part C
6.5. Polar Ice Caps and Old Aquifers . . . . . . . . . . . 6.6. Waste Isolation and Pu in Soil . . . . . . . . . . . . 6.7. Diagnosis of Bone Diseases and Fast Neutron Dosimetry 6.8. Conclusion References and Notes ................. .
Chapter 5 Trapped Ion Spectroscopy Gunther Werth
1. Introduction . 2. Storage ...
2.1. Penning Trap 2.2. rf Trap 2.3. Other Devices 2.4. Ion Creation and Detection
3. Optical Double Resonance Spectroscopy .,. 3.1. Continuous Broadband Light Source: 199Hg+ 3.2. Pulsed Laser Excitation: Ba+ ...... . 3.3. Ion Cooling: 25Mg+ .......... . 3.4. Possible Applications as Frequency Standards
4. Lifetime of Metastable States 5. Conclusion
References . . . . . . . .
Chapter 6
High-Magnetic-Field Atomic Physics J. C. Gay
1. Introduction 1.1. Historical Survey ......... . 1.2. Outlook on the Production of High Fields 1.3. Other Sources of Magnetic Fields 1.4. Atomic Diamagnetism: A Cross-Disciplinary Problem with Wide
Implications in Physics 2. Contents of the Review . . . . 3. The Atom in a Magnetic Field
3.1. Hamiltonian and Symmetries 3.2. The Various Magnetic Regimes in Atomic Spectra
4. Applications of Zeeman Effect at Strong B Fields 4.1. High-Field Anticrossing Experiments . 4.2. Dynamics of Atom-Atom Interactions
5. Landau Regime for Loosely Bound Particles 5.1. Classical Mechanics Aspects . 5.2. Quantum Mechanical Aspects .... 5.3. Spin Effects . . . . . . . . . . . . 5.4. Absorption and Emission of Radiation in the Landau Spectrum
ix
146 146 147 147 147
151 152 152 153 156 157 158 160 163 168 170 171 174 174
177 177 178 178
179 179 180 180 184 185 185 195 205 206 206 208 208
x Contents of Part C
6. Theoretical Concepts of Atomic Diamagnetism . . . . . . 210 6.1. Phenomenological Description of the Atomic Spectrum 211 6.2. Semiclassical WKB Approach 212 6.3. Generalized Semiclassical Methods 213 6.4. Quantum Mechanical Approach 214 6.5. A Brief Review of Other Methods 217 6.6. Dipole Selection Rules and Short-Range Corrections to the Coulomb
Potential ................ 221 6.7. The Hydrogen Atom in Crossed (E, B) Fields 222
7. Experimental Advances in Atomic Diamagnetism 226 7.1. Basis of the Experiments ........ 227 7.2. The Discrete Nature of the Quasi-Landau Spectrum 228 7.3. Conclusions . . . . . . . . . . . . . . . . . . 233
8. Ultra-High-Field Regime and Quantum Electrodynamics 234 8.1. Relativistic Solution for 'Y »1 . . . . . . . . . . 234 8.2. Spontaneous Decay of the Neutral Vacuum at Strong B Fields 235 8.3. Radiation, Chemical Reactivity, and Miscellaneous Questions in Strong
Magnetic Fields ............. 236 8.4. Laboratory Fields and Weakly Bound Particles 237
9. Conclusions 238 References 240
Chapter 7
Effects of Magnetic and Electric Fields on Highly Excited Atoms Charles W. Clark, K. T. Lu, and Anthony F. Starace
1. Introduction . . . . . . . . . . . . . . 2. Diamagnetic Effects in the Hydrogen Atom
2.1. The Equations of Motion ... . . . 2.2. Solutions near the Ionization Threshold
3. Stark Effect in the Hydrogen Atom . . . . 3.1. Semiclassical Treatments: Photoionization Cross Section 3.2. Perturbative Treatment: Excited Rydberg States
4. Nonhydrogenic Atoms in External Fields 4.1. Introduction . . . . . . . . . . . . . . . . 4.2. Quantum Defect Theory of Rydberg Spectra 4.3. Paramagnetism: Channel Mixing Effects on Magnetic Shifts 4.4. Diamagnetism: Magnetic Contribution to Channel Mixing . 4.5. The Stark Effect: Coupling of Parabolic Channels by Scattering from the
Ion Core ............ . 5. Competition of Magnetic and Electric Forces
5.1. Introduction . . . . . . . . . . . . 5.2. The Induced Stark Effect: Coupling of Magnetic Sublevels by Nuclear
Motion .......................... . 5.3. Crossed External Electric and Magnetic Fields: Transition between ~ hwc
and! hwc Spacing ..................... . 6. General Properties of Atoms in Magnetic Fields of Astrophysical Strength
6.1. Atomic Shell Structure 6.2. Magnetic-Field-Induced Binding 6.3. Landau Level Resonances References and Notes . . . . . . .
247 250 250 253 287 287 292 293 293 295 298 300
305 306 306
307
310 313 313 315 315 316
Contents of Part C
ChapterS
X Rays From Superheavy Collision Systems P. H. Mokler and D. Liesen
1. Introduction . . . . . . . 2. Experimental Procedures
2.1. The X-Ray Information 2.2. Total X-Ray Yields 2.3. Impact Parameter Dependences 2.4. Data Reduction
3. Total Excitation Cross Sections 3.1. Experimental Results .. 3.2. Discussion ..... .
4. Impact Parameter Dependences 4.1. Experimental Results 4.2. Discussion ...... .
5. Quasimolecular Radiation . . . 5.1. Spectra and Emission Characteristics 5.2. Coincidence Measurements
6. Spectroscopy of Superheavy Quasimolecules References . . . . . . . . . . . . . . .
Chapter 9
Recoil Ion Spectroscopy with Heavy Ions H. F. Beyer and R. Mann
1. Introduction . . . . . . . . . . . . 2. Some Aspects of Highly Ionized Atoms 3. Experimental Approaches . . . . . .
3.1. Experimental Techniques .... 3.2. Characteristics of Experimental Techniques
4. Production of Highly Charged Target Ions 4.1. Monatomic Targets 4.2. Recoil Energy Distribution 4.3. Molecular Fragmentation . 4.4. Outer-Shell Rearrangement 4.5. Lifetime Measurements . . 4.6. Comparison of Projectile-, Target-, and Plasma-Ion Stripping
5. Secondary Collision Experiments 5.1. Selective Electron Capture 5.2. Potential Applications References . . . . . . . . . .
Chapter 10
Investigations of Superheavy Quasi Atoms via Spectroscopy of 8 Rays and Positrons Hartmut Backe and Christophor Kozhuharov
1. Introduction . . . . . . . . . . . . . . .
xi
321 327 327 330 332 337 340 340 346 355 355 362 375 375 380 383 390
397 399 400 401 407 408 408 427 429 434 437 439 440 442 453 453
459
xii Contents of Part C
2. Spectroscopy of High-Energy 8 Rays 461 2.1. General Considerations . . . . 461 2.2. Physical Quantities in 8-Ray Spectroscopy 463 2.3. Experimental Arrangements . . . . . . 465 2.4. Test of the Basic Concept-"Light" Collisions Systems with Zu < 107 468 2.5. 8-Ray Spectroscopy in the High-Zu Region . . . . . 472
3. Spectroscopy of Positrons . . . . . . . . . . . . . . . 482 3.1. Remarks on Positron Creation in Strong Electric Fields 482 3.2. Physical Quantities in Positron Spectroscopy . . . . . 486 3.3. Experimental Configurations for In-Beam Positron Spectroscopy 487 3.4. Evaluation of Atomic Positrons 493 3.5. Results and Discussion 496
4. Outlook . 500 Appendix 503 References 507
Chapter 11
Impact Ionization by Fast Projectiles Rainer Hippler
1. Introduction . . . . . . . . . . . . . . . 511 1.1. Plane Wave Born Approximation (PWBA) 512 1.2. Semiclassical Approximation (SCA) 517 1.3. Perturbed Stationary States (PSS) Approximation 518
2. Total Cross Sections 520 2.1. Outer Shell Ionization 520 2.2. Outer s-Shell Ionization 528 2.3. Ionization of Inner Shells 531 2.4. Electron Capture 545
3. Differential Cross Sections . . 546 3.1. Differential Cross Sections for 8-Electron Ejection 547 3.2. Impact Parameter Dependence 549
4. Alignment . . . . . 551 4.1. Electron Impact . . . . . . 555 4.2. Proton Impact . . . . . . . 557 4.3. Differential Alignment Measurements 560
5. Applications . . . . . . . . . . . . . 563 5.1. Auger Electron Spectroscopy (AES) 563 5.2. Particle-Induced X-Ray Emission (Pixe) 564 5.3. Proton and Electron Microprobe . . . 566 5.4. Determination of Charge State Distribution of Impurity Ions in Tokamaks 568 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 570
Chapter 12
Amplitudes and State Parameters from lon- and Atom-Atom Excitation Processes T. Andersen and E. Horsdal-Pedersen
1. Introduction . . . . . . . . . . . . 577
Contents of Part C xiii
2. Angular Correlation between Scattered Particles and Autoionization Electrons or Polarized Photons Emitted from States Excited in Atomic Collisions 579 2.1. Photon Emission . . . . . . . 579 2.2. Electron Emission ...... 584 2.3. Selectively Excited Target Atoms. 584
3. Experimental Methods for Obtaining Information' on the Alignment and Orientation Parameters of Atoms or Ions Excited in Specific Collisions 586
4. Results of Experiments and Numerical Calculations 591 4.1. Quasi-One-Electron Systems 592 4.2. He + -He Collisions . . . . . . . .. . . . 603 4.3. Other Collision Systems ......... . 607
5. Future Aspects and Possible Applications of the Polarized-Photon, Scattered-Particle Coincidence Technique to Atomic Spectroscopy . . . . . . . . .. 608 5.1. Future Aspects ......................... 608 5.2. Possible Application of Polarized-Photon, Scattered-Particle Coincidence
Technique to Atomic Spectroscopy 608 References and Notes ... . . . . . . . . . . . . . . . . . . . . .. 609
INDEX 611
Contents of Part A
Contents of Part B .......... . Introduction by W. Hanle and H. Kleinpoppen
xiii XXI
I. BASIC PROPERTIES OF ATOMS AND PERTURBATIONS
Chapter 1 Atomic Structure Theory A. Hibbert
1. Introduction . . . . . . 2. General Theory
2.1. One-Electron Atoms 2.2. Many-Electron Atoms 2.3. Oscillator Strengths
3. Two-Electron Atoms ... 4. Hartree-Fock Theory . . .
4.1. Restricted HF Method 4.2. Solutions of HF Equations
s. Correlation Methods 5.1. Independent-Particle Models 5.2. Configuration Interaction 5.3. Bethe-Goldstone Theory 5.4. Perturbation Methods 5.5. Many-Electron Theory 5.6. Model Potentials
6. Applications . . . . . 6.1. Energy Levels .. 6.2. Oscillator Strengths 6.3. Hyperfine Structure
7. Autoionization . . . 8. Relativistic Methods
References
Chapter 2
Density Matrix Formalism and Applications in Spectroscopy K. Blum
1. Introduction 2. Basic Theory
xv
1 2 2 9
13 18 23 26 29 31 31 33 37 38 42 44 46 46 50 56 59 63 65
71 73
xvi Contents of Part A
2.1. Pure and Mixed Quantum Mechanical States 73 2.2. The Density Matrix and Its Basic Properties 76 2.3. Example: Polarization Density Matrix of Photons 79
3. Interacting Systems . . . . . . . . . . . . 82 3.1. Basic Principles ........... 82 3.2. The Density Matrix of Interacting Systems 83 3.3. Example: Analysis of Light Emitted by Atoms 85
4. Multipole Expansion of the Density Matrix 86 4.1. Irreducible Tensor Operators 86 4.2. Expansion of the Density Matrix in Terms of "State Multipoles" 90 4.3. Symmetry Properties . . . . . 93
5. Time Evolution of Statistical Mixtures 95 5.1. Equations of Motion ..... 95 5.2. Time Evolution of Atomic Ensembles Interacting with Radiation 98 5.3. Perturbed Angular Distributions 103 5.4. The Liouville Formalism 107 References . . . . . . . . . . . . 109
Chapter 3
Perturbation of Atoms Stig Stenholm
1. Introduction 2. Influence of Electromagnetic Fields
2.1. General Considerations . . . 2.2. Semiclassical Theory 2.3. The Quantized Field Approach 2.4. Atoms In Strong Optical Fields 2.5. Two-Photon Spectroscopy
3. Collision Effects ..... . 3.1. Introduction ..... . 3.2. Theoretical Considerations References . . . . . . . . . .
Chapter 4
Quantum Electrodynamical Effects in Atomic Spectra A. M. Ermolaev
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 1.1. Some Recent Developments in Applications of QED to Atomic
Spectroscopy ....... . 1.2. Existing Reviews . . .'. . . . . 1.3. The Layout of the Present Work .
2. The Lamb Shift in One-Electron Atoms 2.1. Summary of Main Theoretical Results 2.2. Comparison between the Theory and Experiment
3. The Lamb Shift in Two-Electron Atoms ..... 3.1. General Form of the Total Energy Expansions .
111 112 112 118 128 135 138 141 141 141 145
149
149 150 151 151 151 158 164 164
Contents of Part A
3.2. Calculations of the Nonrelativistic States 3.3. Relativistic Corrections € cel •••••
3.4. Radiative Corrections . . . . . 3.5. Comparison between the Theory and Experiment (5 States) 3.6. Lamb Shift in P States of Two-Electron Atoms
4. Concluding Remarks References . . . . . . . . . . . . . . . . . .
Chapter 5
Inner Shells B. Fricke
1. Introduction . . . . . . . . . . 2. Binding Energies of Inner Electrons
2.1. Method of Calculation 2.2. Results and Comparison with Experiments
3. Inner-Shell Vacancy Production Mechanisms 3.1. Coulomb Ionization Processes . . . . . 3.2. Molecular Excitation
4. United Atom Phenomena and Related Processes 4.1. Molecular Orbital (MO) X-Rays; REC 4.2. Positron Emission in U-U Collision References . . . . . . . . . . . . . . .
Chapter 6
Interatomic Potentials for Collisions of Excited Atoms W. E. Baylis
1. Background 1.1. Key Role of Interatomic Potentials 1.2. Some Practical Uses 1.3. Standard Potential Forms 1.4. Scope of This Chapter and a Few References
2. Measurements 2.1. Beam Measurements in Ground States 2.2. Beam Measurements in Excited States 2.3. Spectroscopic Measurements of Bound Molecules 2.4. Spectroscopic Measurements of Unbound Molecules 2.5. Transport Coefficients and Other Properties
3. Calculations 3.1. Born-Oppenheimer Approximation and Adiabatic Potentials; Hellmann-
Feynman Theorem 3.2. Hund's Cases and Correlation Diagrams 3.3. Electron-Gas (Gombas) Models 3.4. Induction and Dispersion (van der Waals) Forces 3.5. SCF and Variational Methods 3.6. Pseudo potential and Semiempirical Methods
4. Relation to Collision Processes; Scattering Theory 4.1. Time-Dependent Classical-Path Formulations
xvii
164 166 166 172 174 178 178
183 184 184 186 191 192 196 199 199 202 203
207 207 208 209 212 212 212 218 220 222 222 223
223 226 227 233 236 239 242 242
xviii Contents of Part A
4.2. Semiclassical and JWKB Approximations 4.3. Full Quantum Treatment References . . . . . . . . . .
Chapter 7
II. METHODS AND APPLICATIONS OF ATOMIC SPECTROSCOPY
New Developments of Classical Optical Spectroscopy Klaus Heilig and Andreas Steudel
1. Introduction . . . . . . 2. Experimental Techniques
2.1. Light Sources 2.2. Spectrometers 2.3. Data Handling
3. Fine Structure 3.1. Analysis of Spectra 3.2. Forbidden Lines .
4. Hyperfine Structure 4.1. Hyperfine-Structure Interactions 4.2. Parametric Treatment of the Hyperfine Structure 4.3. Core Polarization ............ . 4.4. Hyperfine Anomaly ........... . 4.5. Optical Hyperfine Investigations of Radioactive Isotopes
5. Isotope Shift . . . . . . . . . . . . . . . 5.1. General Features of Optical Isotope Shifts 5.2. Parametric Method . . 5.3. Specific Mass Shifts ........ . 5.4. Field Shifts and 11/1(0)12 •••... ••
5.5. Field Shifts and Nuclear Deformation Effects 5.6. Calculations of 8(r2)
Appendix: Compilations of Data References . . . . . . . . . .
Chapter 8 Excitation of Atoms by Impact Processes H. Kleinpoppen and A. Scharmann
1. Introduction . . . . . . . . . . 2. Electron Impact Excitation
2.1. Cross Sections and Excitation Functions 2.2. Linear Polarization of Impact Radiation 2.3. Electron-Photon Angular Correlations
3. Heavy-Particle Impact Excitation . . . . . 3.1. Excitation of Atomic Hydrogen and Helium Ions 3.2. Ion Impact Excitation of Other Atoms 3.3. Excitation from Atom-Atom Collisions
4. Conclusions References . . . . . . . . . . . . . . .
249 252 255
263 265 265 269 282 284 284 287 287 287 290 292 293 295 296 296 301 305 306 312 318 319 320
329 330 330 337 349 362 363 369 379 384 386
Contents of Part A
Chapter 9
Perturbed Fluorescence Spectroscopy W. Happer and R. Gupta
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2. Theory .......................... .
2.1. The Production of Fluorescent Light by Polarized Excited Atoms 2.2. Evolution of the Excited Atoms 2.3. Excitation of Atoms
3. Excitation Mechanisms 3.1. Direct Optical Excitation 3.2. Stepwise Optical Excitation 3.3. Cascade Optical Excitation 3.4. Particle Beam Excitation 3.5. Beam-Foil Excitation . . . 3.6. Collisions with Excited Polarized Atoms
4. Basic Spectroscopic Methods ..... . 4.1. Radio-Frequency Spectroscopy (Optical Double Resonance) 4.2. Level-Crossing Spectroscopy ........ . 4.3. Decoupling and Anti-Level-Crossing Spectroscopy 4.4. Light-Modulation Spectroscopy 4.5. Transient Light-Modulation Spectroscopy
5. Experimental Considerations 5.1. Light Sources 5.2. Detectors . . . . . . 5.3. Sample Containers . . 5.4. Optical Filters, Polarizers, Retardation Plates 5.5. Magnetic Fields 5.6. Electric Fields . . . . . . . 5.7. Radio-Frequency Sources .. 5.8. Signal-Processing Equipment
6. A Case Study: Rubidium 6.1. The P States 6.2. The S States 6.3. The D States 6.4. The F States 6.5. The G and Higher Angular Momentum States References and Notes .. . . . . . . . . . . .
Chapter 10
Recent Developments and Results of the Atomic-Beam MagneticResonance Method Siegfried Penselin
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2. Hyperfine-Structure Measurements of Highly Refractory Elements
2.1. Beam Production ................. . 2.2. Results of Measurements Using the Rotating-Target Method
xix
391 397 397 399 401 401 401 403 403 405 409 409 410 410 414 416 421 423 425 425 430 433 434 438 438 439 440 442 442 447 449 458 459 460
463 465 465 469
xx Contents of Part A
3. rf Transitions in the hfs of Metastable Atomic States Detected by Laser Fluorescence ......................... 475
4. Precision Measurements of the hfs of Stable Isotopes ........ 483 4.1. Elimination of Systematic Errors and Precision hfs Measurements of Alkali
Atoms .. . . . . . . . . . . . . . . . . . 483 4.2. Hexadecapole Interaction in the hfs of Free Atoms . . . . . 485 4.3. g] Factor of Li . . . . . . . . . . . . . . . . . . . . . 485
5. hfs Measurements of Radioactive Isotopes (Off-Line and On-Line) 486 References . . . . . . . . . . . . . . . . . . . . . . . . . 487
Chapter 11
The Microwave-Optical Resonance Method William H. Wing and Keith B. MacAdam
1. Introduction . . . . . . . . . . 491 1.1. Method . . . . . . . . . . 491 1.2. Classification of Fine Structure 493 1.3. Rate-Equation Treatment of Line Shape 494
2. Experiments in Lowly Excited States 499 2.1. Fine Structure of Hydrogen and Hydrogenlike Atoms 499 2.2. Relativistic Fine Structure of Helium, Other Atoms, and Molecules 508
3. Experiments in Highly Excited States . . . . . . . . . . . . . . . 509 3.1. Electrostatic and Relativistic Fine Strycture of Helium Rydberg States 509 3.2. Apparatus ......... 514 3.3. Experimental Results in Helium 515 3.4. Series Regularities . . . . . 521 3.5. Measurements in Other Atoms 523 References . . . . . . . . . . . 524
Chapter 12
Lamb-Shift and Fine-Structure Measurements on One-Electron Systems H.-f. Beyer
1. Introduction 1.1. Scope of the Article 1.2. The Fine Structure of Hydrogenic Systems 1.3. Structure of the Article
2. Optical Investigations 2.1. Interferometric Work 2.2. Saturation Spectroscopy 2.3. Ground-State Lamb Shift
3. Slow-Beam and Bottle-Type Investigations 3.1. Signals and Signal Shapes 3.2. Slow-Beam Experiments on H, D, n = 2 3.3. Bottle-Type Experiments
4. Fast-Beam Investigations
529 529 530 533 534 534 537 537 538 538 545 551 567
Contents of Part A
4.1. Measurement of the Stark Quenching Lifetime of 25 4.2. Anisotropy of the 2S Quenching Radiation 4.3. Quantum Beat Experiments . . 4.4. Quenching by Simulated rf Fields 4.5. rf Experiments ..... . 4.6. Separated rf Field Experiments 4.7. Laser Experiments .... .
5. Results ........... . 5.1. Lamb-Shift and Fine-Structure Measurements 5.2. Lamb-Shift Intervals with j > ~ 5.3. The Fine-Structure Constant a References and Notes
Chapter 13
Anticrossing Spectroscopy H.-f. Beyer and H. Kleinpoppen
xxi
567 571 573 578 579 584 589 589 589 598 598 600
1. Introduction . . . . . . . . . . . . . . 607 2. Theory of Anticrossing Signals . . . . . . 609 3. Experimental Studies of Anticrossing Signals 611
3.1. Anticrossings Induced by External Perturbations 612 3.2. Anticrossings Induced by Internal Perturbations 625 3.3. Anticrossings Induced by Combined Internal and External Perturbations. 632 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 636
Chapter 14
Time-Resolved Fluorescence Spectroscopy f. N. Dodd and G. W. Series
1. Introduction: Coherence and Superposition States ........... 639 1.1. Simple Theory of Quantum Beats . . . . . . . . . . . 640 1.2. Methods of Preparation into Superposition States: Sudden Perturbations 643 1.3. Steady-State Excitation and Modulated Excitation: Applications 643 1.4. Coherences between Different Atoms 645
2. Pulsed Excitation: Lifetimes and Quantum Beats . . . . . . 648 2.1. Early Observations of Quantum Beats ........ 649 2.2. Excitation by Light, Theory: Geometrical Characteristics 651 2.3. Superposition States of Mixed Parity 662
3. Pulsed (Stepped) Magnetic and Electric Fields 664 3.1. Pulsed Magnetic Field 664 3.2. Pulsed Electric Field 667 3.3. Pulsed Radio-Frequency Field 667
4. Resolution within the Natural Width 669 4.1. Theory . . . . . . . . . 669 4.2. Practicalities and Examples 672 4.3. Conceptual Problems 673
5. Concluding Remarks 674 References . . . . . . . 675
xxii
Chapter 15
Laser High-Resolution Spectroscopy W. Demtroder
1. Introduction . . . . . . . . . . . . . . 2. Laser Linewidth, Stability, and Tuning
2.1. Multi mode and Single-Mode Operations 2.2. Wavelength Stabilization 2.3. Continuous Wavelength Tuning 2.4. Wavelength Calibration . . . .
3. Atomic Spectroscopy with Multimode Lasers 3.1. Optical Pumping with Lasers 3.2. Stepwise Excitation and Excited-State Spectroscopy 3.3. Laser Photodetachment . . . . . . . . 3.4. Spectroscopy of Atomic Laser Media . . 3.5. High-Sensitivity Absorption Spectroscopy
4. Doppler-Free Laser Spectroscopy ..... 4.1. Laser Spectroscopy in Collimated Atomic Beams 4.2. Saturation Spectroscopy ........ . 4.3. Doppler-Free Two-Photon Spectroscopy 4.4. Laser Optical Double-Resonance Spectroscopy 4.5. Polarization Spectroscopy . . 4.6. The Ultimate Resolution Limit References and Notes
INDEX
Contents of Part A
679 681 681 683 685 686 687 687 688 691 691 692 693 693 697 700 704 707 708 710
xxv
Contents of Part B
Contents of Part A .......... . Introduction by W. Hanle and H. Kleinpoppen
Chapter 16 The Spectroscopy of Highly Excited Atoms Daniel Kleppner
1. Introduction . 2. Experimental Methods 3. Field Ionization 4. Two-Electron Systems
References . . . . .
Chapter 17 Optical Spectroscopy of Short-Lived Isotopes H.-Jiirgen Kluge
xiii XXI
713 714 717 721 724
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 727 2. Information on Nuclear Properties of Short-Lived Isotopes from hfs and IS 728
2.1. Hyperfine Structure ................... 728 2.2. Isotope Shift ...................... 729
3. Nuc1ear-Radiation-Detected Optical Pumping of Short-Lived Isotopes (RADOP) . . . . . . . . . . . . . . . . 730 3.1. The Method . . . . . . . . . . . . . . . . . . . . 731 3.2. In-Beam Experiments on Alkali Isotopes ....... 741 3.3. RADOP Experiments on Mass-Separated Alkali Isotopes 744 3.4. RADOP Experiments on Mass-Separated Hg Isotopes 747
4. Laser Spectroscopy on Short-Lived Isotopes . . 750 4.1. On-Line Laser Spectroscopy of Na Isotopes 751 4.2. On-Line Laser Spectroscopy of Hg Isotopes 753
5. Discussion 760 References . . . . . . . . . . . . 765
xxiii
xxiv
Chapter 18
Spin and Coherence Transfer in Penning Ionization L. D. Schearer and W. F. Parks
Contents of Part B
1. Introduction . . . . . . . . . . . . . . . . . . 769 2. Spin Transfer ................. 769 3. Experimental Conditions for Observing Spin Transfer 770 4. Coherence Transfer in Penning Collisions: Hanle Signals in a Rotating Reference
Frame ................... 773 5. Experimental Observations of Coherence Transfer 774
References . . . . . . . . . . . . . . . . . . 775
Chapter 19
Multiphoton Spectroscopy Peter Briiunlich
1. Introduction . 2. Transition Probabilities for Multiphoton Processes
2.1. Time-Dependent Perturbation Theory 2.2. Calculation of Multiphoton Cross Sections
3. Experimental Investigation of Multiphoton Transition Probabilities 3.1. Photon Statistics . . . . . . . . . . . . . 3.2. Measurements of Multiphoton Cross Sections .....
4. Survey of Multiphoton Emission Phenomena . . . . . . . . 4.1. Stimulated Two-Photon Emission and Raman Scattering 4.2. Optical Mixing
5. Resonance Effects .......... . 6. Polarization Effects . . . . . . . . . . . 7. High-Resolution Multiphoton Spectroscopy
7.1. Multiphoton Ionization Spectroscopy . 7.2. Doppler-Free Spectroscopy ..... 7.3. Applications of Two-Photon Doppler-Free Spectroscopy
8. Concluding Remarks References . . . . . . . . . . . . . . . . . . . . . . .
Chapter 20
Fast-Beam (Beam-Foil) Spectroscopy H. J. Andrii
1. Introduction 2. The Fast-Beam Spectroscopic Source
2.1. Basic Principle ....... . 2.2. Ion-Beam-Target Interaction 2.3. Experimental Equipment and Procedures 2.4. Specific Features of Fast-Beam Spectroscopy
3. Levels and Lifetimes ........... . 3.1. Rydberg Levels ........... . 3.2. Multiply Excited Terms by Photon Detection 3.3. Multiply Excited Terms by Electron Detection
777 779 779 787 790 790 792 796 797 799 802 804 808 808 810 816 821 822
829 833 833 836 841 858 859 861 863 869
Contents of Part B
3.4. Metastable Levels in H- and He-like Ions 3.5. Lamb Shift in High-Z Ions ..... . 3.6. Regularities of Oscillator Strengths . . .
4. Coherence, Alignment, Orientation: "Doppler-Free" Methods 4.1. Quantum Interference-An Introduction ...... . 4.2. Stark Beats .. . . . . . . . . . . . . . . . . . . 4.3. Excitation Symmetry: Foils, Tilted Foils Inclined Surfaces 4.4. Zeeman Beats and Hanle Effect 4.5. Zero-Field Quantum Beats 4.6. High-Field Level Crosssing 4.7. Fast-Beam rf Experiments
5. Selective Laser Excitation 5.1. Precision Lifetimes . . . 5.2. Quantum Beats 5.3. High-Resolution Fluorescence Spectroscopy References and Notes . . . . . . . . . . . .
Chapter 21
Stark Effect K. f. Kollath and M. C. Standage
1. Introduction . . . . . . . . 2. Theory ......... .
2.1. Stark Effect of Hydrogen 2.2. Stark Effect for Nonhydrogenic Atoms
3. Experimental Methods 3.1. Level Crossings 3.2. Level Anticrossings 3.3. The Pulsed-Field Method 3.4. Atomic-Beam Experiments 3.5. Maser and Laser Stark-Effect Experiments 3.6. Summary References . . . . . . . . . . . . . . . .
Chapter 22
Stored Ion Spectroscopy Hans A. Schuessler
1. Introduction . . . . . . . . . 2. The Containment of Isolated Ions
2.1. The Trap Geometry 2.2. Description of the Ion Motion 2.3. Measurement of the Ion Number Signal
3. Reorientation Spectroscopy of Stored Ions . 3.1. The Ion Storage Exchange Collision Method 3.2. State Selection by Selective Quenching of Stored Ions 3.3. Optical Pumping and Laser Spectroscopy of Stored Ions 3.4. Alignment of Ions by Selective Photodissociation . . .
xxv
875 883 885 889 889 893 896 907 912 921 923 923 923 933 936 942
955 957 959 967 972 973 980 982 985 989 993 995
999 1000 1000 1003 1006 1007 1007 1015 1015 1016
xxvi Contents of Part B
4. Limitations of Stored Ion Spectroscopy ....... . 4.1. Line Shifts and Widths of Resonances of Stored Ions 4.2. Pulsed Spin Precession Reorientation Method 4.3. Motional Sideband Spectra ......... .
5. Some Results of Precision Measurements of Stored Ions 6. Conclusion
References . . . . . . . . . . . . . . . . . . . .
Chapter 23
The Spectroscopy of Atomic Compound States J. F. Williams
1. Introduction 2. Experimental Considerations 3. Interpretation of Spectra
3.1. Threshold Spectra 3.2. Line Profiles 3.3. Line Series
4. Atomic Data 4.1. Atomic Hydrogen 4.2. Inert Gas Atoms 4.3. Alkali Atoms 4.4. Atomic Oxygen 4.5. Mercury References . . . . .
Chapter 24
Optical Oscillator Strengths by Electron Impact Spectroscopy W. R. Newell
1. Introduction 2. Apparatus 3. Theory 4. Normalization Procedures 5. Validity of the Born Approximation 6. Extrapolation Procedure . . . . . 7. Summary of Results for Discrete Transitions 8. The Bethe Surface .......... . 9. Continuum Distribution of Oscillator Strength
10. Conclusion References .............. .
Chapter 25
Atomic Transition Probabilities and Lifetimes W. L. Wiese
1. Introduction 2. Basic Concepts
1017 1017 1020 1021 1024 1027 1028
1031 1035 1038 1038 1038 1043 1044 1044 1047 1062 1066 1069 1069
1075 1076 1078 1083 1085 1085 1086 1091 1094 1097 1097
1101 1104
Contents of Part B
3. Transition Probability Measurements 3.1. The Emission Technique 3.2. The Absorption Technique 3.3. The Anomalous Dispersion or "Hook" Technique
4. Transition Probability Calculations 4.1. Advanced Calculations 4.2. Error Bounds 4.3. Relativistic Effects 4.4. High-Volume Calculations
5. Regularities in Atomic Oscillator Strengths 5.1. Systematic Trend of a Given Transition Along an Isoelectronic Sequence. 5.2. Homologous Atoms ..................... . 5.3. Regularities in Spectral Series . . . . . . . . . . . . . . . . . . 5.4. Oscillator Strength Distributions in Spectral Series Along Isoelectronic
Sequences ....... . 6. Lifetimes of Excited Atomic States
6.1. General Remarks ..... 6.2. The Cascading Problem . . . 6.3. Advances in Lifetime Techniques
7. Forbidden Transitions References . . . . . . . . . . . .
Chapter 26
Lifetime Measurement by Temporal Transients Richard G. Fowler
1. Introduction . . 2. Excitation Methods . 3. Observation Methods 4. Data Interpretation 5. Data Processing 6. Results
References . . .
Chapter 27
Line Shapes W. Behmenburg
1. Introduction . . . . . . . . . . . 2. Experimental Methods ..... .
2.1. Influence of Instrumental Effects 2.2. Doppler-Limited Spectroscopy 2.3. Doppler-Free Spectroscopy
3. Atomic Interactions 3.1. Line Center 3.2. Line Wings 3.3. Satellites 3.4. High-Pressure Effects 3.5. ColJisional Line Broadening and Depolarization
xxvii
1106 1106 1115 1120 1122 1122 1124 1126 1127 1129 1129 1131 1132
1133 1135 1135 1136 1143 1147 1149
1157 1157 1160 1166 1174 1177 1185
1187 1188 1188 1189 1192 1194 1196 1205 1210 1215 1217
xxviii Contents of Part B
4. Interaction with Strong Radiation Fields 4.1. Power Broadening . . . . . . . 4.2. Line Splitting: Linear Stark Effect 4.3. Line Shift: Quadratic Stark Effect References . . . . . . . . . . . . .
Chapter 28
Collisional Depolarization in the Excited State W. E. Baylis
1. Introduction: Purpose and Scope 2. Characterizing the Excited State
2.1. Polarization and Multipoles 2.2. Liouville Space and the Density Matrix p 2.3. Time Evolution of p Due to Radiation and Collisions 2.4. Effect of External Fields 2.5. Excited-State Coherence 2.6. When Can Coherence Be Neglected? 2.7. Making and Monitoring the Multipoles
3. Relaxation Matrix 'Y 3.1. Multipole Relaxation Rates 'YL 3.2. mj Mixing Rates 3.3. Symmetries and Selection Rules 3.4. Calculations of 'Y 3.5. Magnetic Field Dependence 3.6. Complications of Nuclear Spin
4. Experimental Methods 4.1. Traditional Measurements in Fluorescence Cells and Flames 4.2. Radiation Trapping and Other Problems 4.3. Broadening of Hanle, Level-Crossing, and Double-Resonance Signals 4.4. Time-Resolved Measurements; Delayed Coincidence 4.5. D2 Optical Pumping 4.6. Isolating the Zeeman Sublevels; High-Field Measurements 4.7. Atomic-Beam Measurements 4.8. Laser Methods of Investigating Depolarization
5. Comparison of Results 5.1. Alkali Depolarization in Collisions with Noble Gases 5.2. Other Depolarization in Foreign-Gas Collisions 5.3. Depolarization in Resonant Collisions References
Chapter 29
Energy and Polarization Transfer M. Etbel
1. Introduction: Transfer of Energy and Polarization 2. Transfer of Energy . . . . . . . . . . . . .
2.1. Experimental ............ . 2.2. Energy Transfer in Collisions of Alkali Atoms with Inert Gas Atoms
1218 1219 1219 1222 1224
1227 1228 1228 1231 1233 1237 1239 1240 1241 1244 1244 1245 1248 1252 1261 1263 1265 1265 1267 1271 1273 1274 1276 1277 1278 1279 1279 1289 1291 1291
1299 1299 1299 1301
Contents of Part B xxix
2.3. Energy Transferin Collisions between Similar and Dissimilar Alkali Atoms 1308 2.4. Energy Transfer in Collisions of Other Dissimilar Atoms 1314
3. Transfer of Alignment and Orientation ............... 1317 3.1. Gough's Prediction . . . . . . . . . . . . . . . . . . . . . . 1320 3.2. Alignment and Orientation Transfer in Collisions of the Second Kind 1324 3.3. Cheron's Analysis of Collisional Transfer 1327 3.4. Transfer between Isotopes of the Same Element 1333 3.5. Hanle Signals in Sensitized Fluorescence 1340 3.6. Transfer between Hyperfine Sublevels 1341 3.7. Transfer between Fine-Structure Sublevels of the Same Element 1347 References
Chapter 30
X-Ray Spectroscopy K.-H. Schartner
1. Introduction . 2. Experimental Techniques . . . . . . . . . .
2.1. Sources for Ions with Inner-Shell Vacancies 2.2. X-Ray Detectors . . . . . . . . . . . .
3. X-Ray Spectra . . . . . . . . . . . . . . . 3.1. Satellite Spectra Emitted in Heavy-Atom Collisions 3.2. Lifetime Measurements . . . . . . . . . . . . 3.3. Satellite Spectra from Plasmas . . . . . . . . . 3.4. Two-Electron-One-Photon Transitions, Radiative Electron
Rearrangement, Radiative Auger Effect 3.5. Continuous X-Ray Spectra
4. Concluding Remarks References . . . . .
Chapter 31
Exotic Atoms G. Backenstoss
1. Introduction . 2. Theoretical Background
2.1. Atomic Cascades 2.2. Level Scheme for a PointIike Nucleus 2.3. Electromagnetic Corrections 2.4. Strong Interaction Effects
3. Experimental Methods 3.1. Generation of the Atoms 3.2. X-Ray Detection
4. Results Obtained from Exotic Atom Data 4.1. Atomic Cascades ....... . 4.2. Particle Properties . . . . . . . . 4.3. Electromagnetic Interactions (Muonic Atoms) 4.4. Strong Interactions-Nuclear Properties 4.5. Outlook References . . . . . . . . . . . . . . .
1352
1357 1358 1358 1359 1362 1362 1368 1370
1372 1377 1382 1383
1385 1389 1389 1390 1392 1395 1396 1396 1398 1401 1401 1406 1408 1416 1424 1425
xxx
Chapter 32
Positronium Experiments Stephan Berko, Karl F; Canter, and Allen P. Mills, Jr.
1. Introduction . . . . . . . . . . . . . . . . . . . 2. Annihilation Selection Rules and Positronium Detection Techniques 3. Tests of Charge Conjugahon Invariance 4. Methods of Positronium Formation . . . . .
4.1. Positronium Formation in Gases . . . . 4.2. Positronium Formation in Oxide Powders 4.3. Slow Positron Beams . . . . . . . . . 4.4. Positronium Production with Slow Positrons
5. Energy-Level Measurements . . . . . . . . . 5.1. The Fine-Structure Interval of the Positronium Ground State 5.2. The Positronium n = 2 State ....... . 5.3. Fine-Structure Measurements in the n = 2 State
6. Positronium Annihilation Rates 7. Future Developments
References . . . . . . . . .
Chapter 33
Applications of Atomic Physics to Astrophysical Plasmas Carole Jordan
1. Introduction 2. Energy Levels and Line Identifications
2.1. Introduction . . . . . . . . . 2.2. Spectra of Solar Active Regions and Flares 2.3. Other Forbidden Lines
3. Atomic Data for Plasma Diagnostics 3.1. Oscillator Strengths 3.2. Collision Cross Sections References . . . . . . . .
Chapter 34
Wavelength Standards Kenneth M. Baird
1. Introduction . . 2. Sources . . . . 3. Measurement Methods 4. The Primary Standard 5. Laser Standards 6. Secondary Standards
References . . . . .
INDEX
Contents of Part B
1427 1428 1430 1430 1431 1432 1433 1434 1436 1436 1441 1442 1447 1450 1450
1453 1454 1454 1456 1461 1467 1467 1470 1481
1485 1487 1488 1491 1493 1496 1499
xxv
Introduction
H. J. BEYER AND H. KLEINPOPPEN
During the preparation of Parts A and B of Progress in Atomic Spectroscopy a few years ago, it soon became obvious that a comprehensive review and description of this field of modern atomic physics could not be achieved within the limitations of a two-volume book. While it was possible to include a large variety of spectroscopic methods, inevitably some fields had to be cut short or left out altogether. Other fields have developed so rapidly that they demand full cover in an additional volume.
One of the major problems, already encountered during the preparation of the first volumes, was to keep track of new developments and approaches which result in spectroscopic data. We have to look far beyond the area of traditional atomic spectroscopy since methods of atomic and ion collision physics, nuclear physics, and even particle physics all make important contributions to our knowledge of the static and dynamical state of atoms and ions, and thereby greatly add to the continuing fascination of a field of research which has given us so much fundamental knowledge since the middle of the last century.
In this volume, we have tried to strike a balance between contributions belonging to the more established fields of atomic structure and spectroscopy and those fields where atomic spectroscopy overlaps with other areas.
Present day atomic structure theory is successfully dealing with more and more complex atoms and making considerable progress in improving and extending approximation methods, as is borne out by the contribution on multiconfiguration calculations. On the other hand, there is still scope for surprisingly basic problems like that of ordering atomic levels in simple terms. The method of k-ordering of atomic structure is remarkably successful and reminds us of the classical period of unraveling spectroscopic data in terms of spectral line series.
xxxi
xxxii Introduction
Efforts are continually being made to improve established methods and to develop new ones with the aim of advancing the accuracy of atomic structure measurements and of extending the range of application to more atomic systems. Recently this was to some extent linked to the steady development of the laser both in terms of output characteristics and of spectral range. It was, therefore, felt that the latest developments in the field of lasers and laser spectroscopy should be reviewed again. Lasers are proving to be particularly powerful tools when used in conjunction with other techniques. In this way resonant laser absorption combined with ion detection techniques allows single atom detection and counting. Similarly, the already high resolution obtained in trapped ion spectroscopy can be increased even further by laser absorption cooling which results in a relative accuracy of the order of 10-15 and may ultimately lead to the time standard of the future.
Atoms in high fields have always represented a fascinating area of research. Landau spectroscopy, atomic diamagnetism, neutral vacuum decay in ultrastrong fields are not only interesting from the point of view of fundamental knowledge but have far-reaching consequences in astrophysics. Until recently experimental studies were severely restricted by the available magnetic field strength, but progress in the development of superconducting magnets and in the spectroscopy of highly excited states is rapidly closing this gap.
The introduction of heavy ion accelerators and the resulting possibility of studying fast heavy ion collisions is leading to completely new types of spectroscopy. Such collisions may cause the transient formation of superheavy quasi atoms or quasi molecules having an effective nuclear charge given by the sum of the charges of the colliding partners. As a result of the short time scale of these collisions the systems can be studied in ultra-high electromagnetic fields. Tools for such investigations are x-ray spectroscopy, ion recoil spectroscopy, and spectroscopy of 8 rays and positrons. Also, highly charged ions can be produced in single-ion collisions and open new avenues of research. New methods have been developed for the detection of these collision products and the extraction of spectroscopic data. The methods and their results are described in three chapters.
Low-energy ion-atom collisions are also providing typical spectroscopic data for collision products. Alignment and orientation parameters of states excited by ion bombardment can be extracted from angular correlation measurements. Coherent impact excitation of atoms manifests itself in angular correlations between emitted photons and scattered particles or in quantum beats of the related photon intensities. Population amplitudes and their phase differences can also be obtained and provide insight into the excitation mechanism of ions and atoms. The interplay between atomic potential curves and the quasimolecular structure of colliding atomic parti-
Introduction xxxiii
cles is important to the understanding of atomic excitation processes. There are significant links between such low-energy spectroscopic collision data and fields of applied research such as plasma and fusion physics.
Wilhelm Hanle's name will always be connected with his pioneering work on quantum mechanical interference of atomic states, now generally known as the Hanle effect, which he carried out shortly after the advent of modern quantum mechanics. Of course his research activity, which has been summarized and praised on many occasions, was not restricted to atomic spectroscopy. In fact, it reaches far beyond even the field of atomic physics. Nevertheless, his primary interest has always been in atomic spectroscopy and atomic collision physics, two fields from which much of the experimental spectroscopic information reported in this volume is drawn. It is, therefore, fitting to dedicate this volume and the following Part D to Professor Hanle. This dedication is even more appropriate as Professor Hanle was an enthusiastic editor of Parts A and B of Progress in Atomic Spectroscopy, but did not wish to take the burden of continued editorship. Nevertheless, he took great interest in this new project, and the present editors are very grateful for his advice and for suggestions of topics to be included. The authors and editors are most happy to honor Wilhelm Hanle by their contributions.
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