Surface Analysis

John C. Vickerman BSc in Chemistry (Edinburgh), Ph.D. in Surface Chemistry (Bristol), DSc (Bristol). Predoctoral fellowships at the Universities of Perugia and Rome, postdoctoral fellowships at the University of Bristol and the Technical University of Eindhoven. Sabbatical study periods at the University of Munich, the Free University of Berlin and Pennsylvania State University.Dr Ian Gilmore, Surface and Nano-Analysis, National Physical Laboratory, Teddington, UKIan is a Principal Research Scientist in the Surface and Nano-Analysis Research team and joined NPL in 1991. His research has a focus on the analysis of complex molecules at surfaces. Recent research has led to the development of a novel new variant of static static SIMS called gentle-SIMS or G-SIMS,He received a degree in Physics from the University of Manchester in 1991 and a PhD from the University of Loughborough in 2000. Ian is a Fellow of the Institute of Physics a member of the EPSRC College and a member of the American Vacuum Society.

• List of Contributors xvPreface xvii1 Introduction 1John C. Vickerman1.1 How do we Define the Surface? 11.2 How Many Atoms in a Surface? 21.3 Information Required 31.4 Surface Sensitivity 51.5 Radiation Effects – Surface Damage 71.6 Complexity of the Data 82 Auger Electron Spectroscopy 9Hans Jörg Mathieu2.1 Introduction 92.2 Principle of the Auger Process 102.2.1 Kinetic Energies of Auger Peaks 112.2.2 Ionization Cross-Section 152.2.3 Comparison of Auger and Photon Emission 162.2.4 Electron Backscattering 172.2.5 Escape Depth 182.2.6 Chemical Shifts 192.3 Instrumentation 212.3.1 Electron Sources 222.3.2 Spectrometers 242.3.3 Modes of Acquisition 242.3.4 Detection Limits 292.3.5 Instrument Calibration 302.4 Quantitative Analysis 312.5 Depth Profile Analysis 332.5.1 Thin Film Calibration Standard 342.5.2 Depth Resolution 362.5.3 Sputter Rates 372.5.4 Preferential Sputtering 402.5.5 λ-Correction 412.5.6 Chemical Shifts in AES Profiles 422.6 Summary 43References 44Problems 453 Electron Spectroscopy for Chemical Analysis 47Buddy D. Ratner and David G. Castner3.1 Overview 473.1.1 The Basic ESCA Experiment 483.1.2 A History of the Photoelectric Effect and ESCA 483.1.3 Information Provided by ESCA 493.2 X-ray Interaction withMatter, the Photoelectron Effect and Photoemission from Solids 503.3 Binding Energy and the Chemical Shift 523.3.1 Koopmans’ Theorem 533.3.2 Initial State Effects 533.3.3 Final State Effects 573.3.4 Binding Energy Referencing 583.3.5 Charge Compensation in Insulators 603.3.6 Peak Widths 613.3.7 Peak Fitting 623.4 Inelastic Mean Free Path and Sampling Depth 633.5 Quantification 673.5.1 Quantification Methods 683.5.2 Quantification Standards 703.5.3 Quantification Example 713.6 Spectral Features 733.7 Instrumentation 803.7.1 Vacuum Systems for ESCA Experiments 803.7.2 X-ray Sources 823.7.3 Analyzers 843.7.4 Data Systems 863.7.5 Accessories 883.8 Spectral Quality 883.9 Depth Profiling 893.10 X–Y Mapping and Imaging 943.11 Chemical Derivatization 963.12 Valence Band 963.13 Perspectives 993.14 Conclusions 100Acknowledgements 101References 101Problems 1094 Molecular Surface Mass Spectrometry by SIMS 113John C. Vickerman4.1 Introduction 1134.2 Basic Concepts 1164.2.1 The Basic Equation 1164.2.2 Sputtering 1164.2.3 Ionization 1214.2.4 The Static Limit and Depth Profiling 1234.2.5 Surface Charging 1244.3 Experimental Requirements 1254.3.1 Primary Beam 1254.3.2 Mass Analysers 1314.4 Secondary Ion Formation 1404.4.1 Introduction 1404.4.2 Models of Sputtering 1434.4.3 Ionization 1494.4.4 Influence of the Matrix Effect in Organic Materials Analysis 1514.5 Modes of Analysis 1554.5.1 Spectral Analysis 1554.5.2 SIMS Imaging or Scanning SIMS 1664.5.3 Depth Profiling and 3D Imaging 1734.6 Ionization of the Sputtered Neutrals 1834.6.1 Photon Induced Post-Ionization 1844.6.2 Photon Post-Ionization and SIMS 1904.7 Ambient Methods of Desorption Mass Spectrometry 194References 199Problems 2035 Dynamic SIMS 207David McPhail and Mark Dowsett5.1 Fundamentals and Attributes 2075.1.1 Introduction 2075.1.2 Variations on a Theme 2115.1.3 The Interaction of the Primary Beam with the Sample 2145.1.4 Depth Profiling 2175.1.5 Complimentary Techniques and Data Comparison 2245.2 Areas and Methods of Application 2265.2.1 Dopant and Impurity Profiling 2265.2.2 Profiling High Concentration Species 2275.2.3 Use of SIMS in Near Surface Regions 2305.2.4 Applications of SIMS Depth Profiling in Materials Science 2335.3 Quantification of Data 2335.3.1 Quantification of Depth Profiles 2335.3.2 Fabrication of Standards 2395.3.3 Depth Measurement and Calibration of the Depth Scale 2415.3.4 Sources of Error in Depth Profiles 2425.4 Novel Approaches 2465.4.1 Bevelling and Imaging or Line Scanning 2465.4.2 Reverse-Side Depth Profiling 2505.4.3 Two-Dimensional Analysis 2515.5 Instrumentation 2525.5.1 Overview 2525.5.2 Secondary Ion Optics 2535.5.3 Dual Beam Methods and ToF 2545.5.4 Gating 2545.6 Conclusions 256References 257Problems 2676 Low-Energy Ion Scattering and Rutherford Backscattering 269Edmund Taglauer6.1 Introduction 2696.2 Physical Basis 2716.2.1 The Scattering Process 2716.2.2 Collision Kinematics 2726.2.3 Interaction Potentials and Cross-sections 2756.2.4 Shadow Cone 2786.2.5 Computer Simulation 2816.3 Rutherford Backscattering 2846.3.1 Energy Loss 2846.3.2 Apparatus 2876.3.3 Beam Effects 2896.3.4 Quantitative Layer Analysis 2906.3.5 Structure Analysis 2936.3.6 Medium-Energy Ion Scattering (MEIS) 2976.3.7 The Value of RBS and Comparison to Related Techniques 2986.4 Low-Energy Ion Scattering 3006.4.1 Neutralization 3006.4.2 Apparatus 3036.4.3 Surface Composition Analysis 3076.4.4 Structure Analysis 3166.4.5 Conclusions 323Acknowledgement 324References 324Problems 330Key Facts 3307 Vibrational Spectroscopy from Surfaces 333Martyn E. Pemble and Peter Gardner7.1 Introduction 3337.2 Infrared Spectroscopy from Surfaces 3347.2.1 Transmission IR Spectroscopy 3357.2.2 Photoacoustic Spectroscopy 3407.2.3 Reflectance Methods 3427.3 Electron Energy Loss Spectroscopy (EELS) 3617.3.1 Inelastic or ‘Impact’ Scattering 3627.3.2 Elastic or ‘Dipole’ Scattering 3657.3.3 The EELS (HREELS) Experiment 3677.4 The Group Theory of Surface Vibrations 3687.4.1 General Approach 3687.4.2 Group Theory Analysis of Ethyne Adsorbed at a Flat, Featureless Surface 3697.4.3 Group Theory Analysis of Ethyne Adsorbed at a (100) Surface of an FCC Metal 3737.4.4 The Expected Form of the RAIRS and Dipolar EELS (HREELS) Spectra 3747.5 Laser Raman Spectroscopy from Surfaces 3757.5.1 Theory of Raman Scattering 3767.5.2 The Study of Collective Surface Vibrations (Phonons) using Raman Spectroscopy 3777.5.3 Raman Spectroscopy from Metal Surfaces 3797.5.4 Spatial Resolution in Surface Raman Spectroscopy 3807.5.5 Fourier Transform Surface Raman Techniques 3807.6 Inelastic Neutron Scattering (INS) 3817.6.1 Introduction to INS 3817.6.2 The INS Spectrum 3827.6.3 INS Spectra ofHydrodesesulfurization Catalysts 3827.7 Sum-Frequency Generation Methods 383References 386Problems 3898 Surface Structure Determination by Interference Techniques 391Christopher A. Lucas8.1 Introduction 3918.1.1 Basic Theory of Diffraction – Three Dimensions 3928.1.2 Extension to Surfaces – Two Dimensions 3988.2 Electron Diffraction Techniques 4028.2.1 General Introduction 4028.2.2 Low Energy Electron Diffraction 4038.2.3 Reflection High Energy Electron Diffraction (RHEED) 4188.3 X-ray Techniques 4248.3.1 General Introduction 4248.3.2 X-ray Adsorption Spectroscopy 4278.3.3 Surface X-ray Diffraction (SXRD) 4478.3.4 X-ray Standing Waves (XSWs) 4568.4 Photoelectron Diffraction 4648.4.1 Introduction 4648.4.2 Theoretical Considerations 4658.4.3 Experimental Details 4698.4.4 Applications of XPD and PhD 470References 4749 Scanning Probe Microscopy 479Graham J. Leggett9.1 Introduction 4799.2 Scanning Tunnelling Microscopy 4809.2.1 Basic Principles of the STM 4819.2.2 Instrumentation and Basic Operation Parameters 4879.2.3 Atomic Resolution and Spectroscopy: Surface Crystal and Electronic Structure 4899.3 Atomic Force Microscopy 5119.3.1 Basic Principles of the AFM 5119.3.2 Chemical Force Microscopy 5249.3.3 Friction Force Microscopy 5269.3.4 Biological Applications of the AFM 5329.4 Scanning Near-Field Optical Microscopy 5379.4.1 Optical Fibre Near-Field Microscopy 5379.4.2 Apertureless SNOM 5419.5 Other Scanning Probe Microscopy Techniques 5429.6 Lithography Using Probe Microscopy Methods 5449.6.1 STM Lithography 5449.6.2 AFM Lithography 5459.6.3 Near-Field Photolithography 5499.6.4 The ‘Millipede’ 5509.7 Conclusions 551References 552Problems 55910 The Application of Multivariate Data Analysis Techniques in Surface Analysis 563Joanna L.S. Lee and Ian S. Gilmore10.1 Introduction 56310.2 Basic Concepts 56510.2.1 Matrix and Vector Representation of Data 56510.2.2 Dimensionality and Rank 56710.2.3 Relation to Multivariate Analysis 56810.2.4 Choosing the Appropriate Multivariate Method 56810.3 Factor Analysis for Identification 56910.3.1 Terminology 57010.3.2 Mathematical Background 57010.3.3 Principal Component Analysis 57110.3.4 Multivariate Curve Resolution 57910.3.5 Analysis of Multivariate Images 58210.4 Regression Methods for Quantification 59110.4.1 Terminology 59110.4.2 Mathematical Background 59210.4.3 Principal Component Regression 59410.4.4 Partial Least Squares Regression 59510.4.5 Calibration, Validation and Prediction 59610.4.6 Example – Correlating ToF–SIMS Spectra with PolymerWettability Using PLS 59810.5 Methods for Classification 60010.5.1 Discriminant Function Analysis 60110.5.2 Hierarchal Cluster Analysis 60210.5.3 Artificial Neural Networks 60310.6 Summary and Conclusion 606Acknowledgements 608References 608Problems 611Appendix 1 Vacuum Technology for Applied Surface Science 613Rod WilsonA1.1 Introduction: Gases and Vapours 613A1.2 The Pressure Regions of Vacuum Technology and their Characteristics 619A1.3 Production of a Vacuum 622A1.3.1 Types of Pump 622A1.3.2 Evacuation of a Chamber 634A1.3.3 Choice of Pumping System 635A1.3.4 Determination of the Size of Backing Pumps 636A1.3.5 Flanges and their Seals 636A1.4 Measurement of Low Pressures 637A1.4.1 Gauges for Direct Pressure Measurement 638A1.4.2 Gauges Using Indirect Means of Pressure Measurement 640A1.4.3 Partial Pressure Measuring Instruments 644Acknowledgement 647References 647Appendix 2 Units, Fundamental Physical Constants and Conversions 649A2.1 Base Units of the SI 649A2.2 Fundamental Physical Constants 650A2.3 Other Units and Conversions to SI 651References 652Index 653