Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact

by Chaudhry, Afzal; Kleinpoppen, Hans

• ISBN13: 9781441969460
• ISBN10: 1441969462
• Format: Hardcover
• Copyright: 2010-10-01
• Publisher: Springer Verlag

Summary

The content of this book describes in detail the results of the present measurements of the partial and total doubly differential cross sections for the multiple-ionization of rare gas atoms by electron impact. These measurements show, beside other trends, the role of Auger transitions in the production of multiply ionized atoms in the region where the incident electron energy is sufficient to produce inner shell ionization. Other processes like Coster-Kronig transitions and shake off also contribute towards increasing the charge of the ions. The incident electron having energy of 6 keV, for example, in a collision with xenon atom can remove up to nine electrons! (*) X-ray-ion coincidence spectroscopy of the electron xenon atom collisions is also described. The present measurements of doubly differential cross sections for the dissociative and non-dissociative ionization of hydrogen, sulfur dioxide and sulfur hexa fluoride molecular gases by electron impact are also described in the text of this book. The results of the measurements for sulfur dioxide molecule show how this major atmospheric pollutant can be removed from the atmosphere by electron impact dissociation of this molecule. The present results of the measurements for sulfur hexa fluoride give an insight into the dissociation properties of this molecular gas, which is being so widely used as a gaseous insulator in the electrical circuits. The book also describes the present measurements of the polarization parameters of the fluorescence radiation emitted by the electron-impact-excited atoms of sodium and potassium. In these investigations the target atoms are polarized, therefore, the measurements of the polarization parameters give information about the electron atom interaction in terms of the interference, direct and exchange interaction channels.

Author Biography

Hans Kleinpoppen is Editor of Polarized Electron/Polarized Photon Physics (Springer, 1995) and Selected Topics on Electron Physics (Springer, 1996).

Table of Contents

Introduction	p. 1
Ionization of Atomic Gases	p. 1
Ionization of Hydrogen, Sulphur Dioxide and Sulphur Hexa Fluoride	p. 4
Excitation of Polarized Sodium and Potassium Atoms	p. 6
Excitation of Alkaline Earth Metal Atoms of Calcium and Strontium	p. 10
Excitation-Ionization of the Calcium Atom by Electron Impact	p. 11
Measurement of Coherence and Polarization Parameters for the Excitation of the 5 1P State of Strontium	p. 12
Polarization Correlation Measurements of 3 1P State of Helium	p. 12
Polarization Correlation Measurements on the 33P State of Helium	p. 13
Theoretical Approaches	p. 15
Ionization Cross Sections of Atomic Gases by Electron Impact	p. 15
Double Differential Cross Sections of Ionization	p. 16
First Born Approximation	p. 16
Plane-Wave Born Approximation	p. 17
Binary Encounter Theory	p. 18
The Inner Shell Ionization	p. 19
Electron Vacancy Transitions of Atoms	p. 20
Characteristic and Continuum X-Rays	p. 24
Close-Coupling Approach to Electron-Impact Ionization	p. 24
Partial Double-Differential Cross Section for Ionization	p. 25
The Ionization of Hydrogen, Sulphur Dioxide and Sulphur Hexafluoride	p. 26
Excitation of Spin-Polarized Sodium and Potassium Atoms by Electron Impact	p. 28
Preparation of the State-Selected Na and K Atomic Beams	p. 28
The Collision Induced S-P Excitation	p. 30
Fine and Hyperfine Interaction of the Excited States	p. 33
Polarization of the Fluorescence Radiation	p. 34
Apparatus for the electron-atom collision studies	p. 37
Apparatus for the Electron-Atom Collision Studies	p. 37
The Apparatus for Detecting Photons and Atomic Particles	p. 37
The Vacuum Chamber for Housing the Apparatus	p. 38
The Electron Gun and the Faraday Cup	p. 40
The Atomic/Molecular Beam Source	p. 41
The Electron Analyzer	p. 41
The Ion Analyzer	p. 43
The Negative Ions	p. 45
High-Voltage Power Supplies, Multi-channel Analyzer and Other Electronic Equipment	p. 47
Hyper Pure Germanium (HPGe) X-Ray Detector	p. 47
Energy Structure of Inner Shells, X-Ray Spectra, Augér Effect and Coster-Kronig Transitions	p. 48
Bremsstrahlung X-Rays	p. 63
Crystal X-Ray Spectrometer	p. 68
The Apparatus for the Electron-Molecule Collision Process	p. 74
The Apparatus and the Electronic Equipment Used in the Experiment	p. 74
Apparatus for the Study of the Excitation of Spin-Polarized Atoms of Sodium and Potassium	p. 74
Vacuum Chambers for Housing the Apparatus	p. 74
Cancellation of the Earth's Magnetic Field	p. 75
The Components of the Atomic Beam Apparatus	p. 75
Guiding Fields and the Low Field Polarization of Atoms	p. 85
The Rabi Magnet	p. 87
Langmuir-Taylor Detector and the Atomic Beam Density	p. 88
The Electron Beam Components	p. 91
Photon Detection System	p. 96
Apparatus for the Study of Excitation of Calcium	p. 97
The Vacuum System	p. 97
The Atomic Beam Source	p. 98
Atomic Beam Density	p. 100
The Electron Gun	p. 102
Apparatus for the Study of Excitation of Strontium	p. 102
The Vacuum Chamber	p. 102
The Atomic Beam Source	p. 102
The Atomic Beam Density	p. 103
The Electron Gun	p. 103
The Electron Energy Analyzer	p. 103
Apparatus for the Study of Excitation of Helium	p. 104
Experimental Techniques	p. 107
Electron-Ion Coincidence Technique for the Investigation of Multiple Ionization of Atomic Gases	p. 107
X-Ray-Ion Coincidence Technique	p. 110
Crystal X-Ray Spectrometer	p. 111
Experimental Technique for the Investigation of the Ionization of the Molecular Gases	p. 113
Experimental Technique for the Measurement of the Polarization Parameters of the Induced Fluorescent Radiation in Electron-Polarized Atom Collision Process	p. 117
The Polarization Parameters of the Fluorescent Radiation	p. 118
The Corrections for the Measurement of the Polarization of the Fluorescence Radiation	p. 119
Hanle Effect and the Depolarization of the Fluorescent Radiation	p. 121
Fine and Hyperfine Structure of Sodium and Potassium Atoms	p. 123
Hanle Effect Depolarization of the Observed States in Sodium and Potassium Atoms	p. 127
Experimental Techniques for the Investigation of Electron Impact Excitation of Calcium and Strontium Atoms	p. 130
Experimental Technique for the Study of Excitation of Calcium Atoms	p. 130
Experimental Technique for the Excitation of Strontium Atoms	p. 132
Experimental Technique for the Study of 3 1P State of Helium	p. 135
Electron Impact Excitation of 3 3P State of Helium	p. 137
Results and Discussion	p. 139
Measurement of the Ionization Cross Sections for Atomic Gases	p. 139
Helium	p. 140
Argon	p. 141
Krypton	p. 151
Xenon	p. 152
Neon	p. 160
X-Ray-Ion Coincidence Measurements	p. 161
X-Ray Spectroscopy Using a Crystal X-Ray Spectrometer	p. 161
Measurement of the Ionization Cross Sections for Molecular Gases	p. 162
Hydrogen	p. 162
Sulphur Dioxide	p. 168
Sulphur Hexaflouride (SF6)	p. 181
Measurements for the Polarization of the Fluorescent Radiation Emitted by Sodium and Potassium Atoms	p. 192
Measurements for the Polarization of the Fluorescent Radiation Emitted by the Sodium Atom	p. 192
Measurements for the Polarization of the Fluorescent Radiation Emitted by the Potassium Atom	p. 197
The Excitation of Calcium and Strontium Atoms	p. 200
Excitation Function of Ca II Line of Wavelength ¿ = 393.3 nm	p. 200
Absolute Cross Section for the Ca II 4 2P1/2 State	p. 201
Polarization of the Ca II, ¿ = 393.3 nm (4 2P3/2← 42S1/2) Transition	p. 202
The Coherence and Polarization Parameter Measurements for the Excitation the 5 1P State in Strontium	p. 203
Excitation of 3 1P State of Helium	p. 209
Excitation of 3 3P State of Helium	p. 211
Conclusion	p. 217
Bibliography	p. 221
Index	p. 231
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