A unified Monte Carlo approach for quantitative standardless X-ray fluorescence and electron probe microanalysis inside the scanning electron microscope [Elektronische Ressource] = Ein vereinheitlichter Monte-Carlo-Ansatz zur quantitativen standardfreien Röntgenfluoreszenz und Elektronenstrahlmikroanalyse im Rasterelektronenmikroskop / vorgelegt von Stefan Steinbrecher

Angelika Gross

Sujets

• Naturwissenschaften

Informations

• Publié par: eberhard_karls_universitat_tubingen
• Publié le: 01 janvier 2004
• Nombre de lectures: 22
• Langue: Deutsch
• Poids de l'ouvrage: 2 Mo

Extrait

A Unified Monte Carlo Approach for Quantitative Standardless X-Ray
Fluorescence and Electron Probe Microanalysis inside the Scanning
Electron Microscope

***

Ein Vereinheitlichter Monte-Carlo-Ansatz zur Quantitativen
Standardfreien Röntgenfluoreszenz - und Elektronenstrahl-
mikroanalyse im Rasterelektronenmikroskop



Dissertation



Zur Erlangung des Grades eines Doktors der Naturwissenschaften
der Fakultät für Mathematik und Physik
der Eberhard-Karls-Universität Tübingen



vorgelegt von
Stefan Steinbrecher
aus Ludwigshafen/Rhein



2004




























Tag der mündlichen Prüfung : 6. Juli 2004
Dekan Prof. Dr. H. Müther
1. Bericherstatter : Prof. Dr. E. Plies
2. Berichterstatter : Prof. Dr. O. Eibl
3. Berichterstatter : Prof. Dr. J. Wernisch


Die vorliegende Arbeit wurde am
Institut für Angewandte Physik,
Eberhard-Karls-Universität Tübingen,
in der Arbeitsgruppe von
Herrn Prof. Dr. E. Plies
angefertigt.


















Herrn Prof. Dr. E. Plies möchte ich an dieser Stelle für die freundliche Aufnahme in seine
Arbeitsgruppe,
die Möglichkeit, das vorliegende Thema zu bearbeiten und die Ergebnisse auf Tagungen zu
präsentieren,
die hervorragenden Arbeitsbedingungen, sowie sein Interesse an dieser Arbeit und die
gewährte Unterstützung

sehr herzlich danken !













































Wer immer tut, was er schon kann,
bleibt immer das, was er schon ist.


HENRY FORD






















































TABLE OF CONTENTS

Abstract I

Kurzfassung III

Definitions VII

Constants VII
List of Abbreviations VIII
List of Symbols and Definitions IX
Subscripts XIII
Superscripts XIV
Prefixes XIV
Units XV

Introduction 1


I. THEORETICAL ASPECTS OF X-RAY EMISSION SPECTROSCOPY

1 X-Ray Emission Spectroscopy 3

1.1 X-Ray Emission Spectroscopic Techniques 3
1.2 Dispersive Detection of X-Rays 6

2 Generation of Characteristic X-Ray Spectra 9

2.1 Interaction of X-Rays with Matter 12
2.1.1 Photoelectric Interaction 14
2.1.2 Photon Scattering 15
2.2 Interaction of Electrons with Matter 17
2.2.1 Elastic Electron Scattering 17
2.2.2 Inelastic Electron Scattering 21
2.2.3 Inner Shell Ionisation by Electron Impact 23
2.3 Description of Multiple Electron Energy Losses 25
2.3.1 Continuous Electron Energy Loss Approximation 25
2.3.2 Phenomenology of Electron Scattering 27
2.3.3 Depth Distribution of Characteristic X-Ray Generation 29


3 Quantification Methods in X-Ray Emission Spectroscopy 33

3.1 The Analytical Problem 33
3.1.1 Empirical Coefficient Methods 34
3.1.2 Fundamental Parameter 35
3.2 Quantitative X-Ray Fluorescence Analysis 38
3.2.1 Monochromatic Excitation 38
3.2.2 Polychromatic 40
3.3 Quantitative Electron Probe Microanalysis 41
3.3.1 Atomic Number (Z-) Correction 42
3.3.2 Absorption (A-) Correction 43
3.3.3 The ϕ (ρz) Technique 44
3.3.4 Fluorescence (F-) Correction 46
3.4 Modelling the Detection Process 47
3.4.1 Detector Resolution and Efficiency 48
3.4.2 Detector Artifacts 50
3.5 Matrix Correction Procedures in Practice 51
3.6 Analytical Sensitivity and Detection Limits 53









II. COMPUTATIONAL METHODS

4 Monte Carlo Simulation of X-Ray Emission Spectra 57

4.1 The Fundamental Computational Procedure 58
4.2 The Spectral Response of X-Ray Excited Samples 60
4.2.1 X-Ray Source Emission 62
4.2.2 Photon-Matter Interactions 66
4.2.3 Modelling the Photoelectric Effect 67
4.2.4 Modelling Photon Scattering 68
4.2.5 Probabilistic Interpretation of X-Ray Emission 72
4.3 The Spectral Response of Electron Excited Samples 74
4.3.1 Electron Diffusion 75
4.3.2 Implementation of X-Ray Emission 77
4.4 Processing of Simulation Data 80
4.4.1 Conversion of Simulation Data into Spectra 80
4.4.2 Comparison of Experimental and Simulated Data 82
4.5 Conclusions 83


III. RESULTS AND DISCUSSION

5 X-Ray Fluorescence Analysis in the Scanning Electron Microscope 85

5.1 Lowering the Detection Limits in the Scanning Electron Microscope 85
5.2 Sample Holder Design 89
5.2.1 Instrumental Parameters and Geometric Preconditions 89
5.2.2 Implementation 90
5.3 Characterisation of X-Ray Sources 93
5.3.1 Spectral Distribution of X-Ray Source Emission 93
5.3.2 Angular 103
5.4 Performance of X-Ray Fluorescence Analysis 106
5.4.1 Adjustment and Efficiency of Excitation 106
5.4.2 X-Ray Scatter Peaks 112
5.5 Conclusions 114

6 Application of Monte Carlo Methods in X-Ray Emission Spectroscopy 117

6.1 Assessment of Fundamental Parameters in Electron Microprobe Analysis 117
6.1.1 Backscatter Coefficient and Energy Spectra of Backscattered Electrons 117
6.1.2 Intensity of Characteristic Radiation 122
6.2 Simulation of X-Ray Emission Spectra 125
6.3 Quantitative X-Ray Emission Spectroscopy 129
6.4 Computation Speed 139
6.5 Detection Limits 143
6.6 Conclusions 145

7 Further Applications 147

7.1 Determination of k Ratios and Detection of Fluorescent Pathways 147
7.2 Thin Samples 151
7.3 Tilted Samples 159
7.4 Conclusions 160

8 Summary 163

9 Appendix 171

9.1 Flow Diagrams of Monte Carlo Algorithms 171
9.2 Construction Drawings of the X-Ray Fluorescence Specimen Stage 174
9.3 Resolution of the EDS Detection System 180
9.4 List of Materials Utilised to Construct the X-Ray Fluorescence Facilities 181
9.5 List of Samples and Experimental Conditions for Quantitative Analysis 182


10 References 185