Principles of Field Ionization and Field Desorption Mass Spectrometry

Preface

Introduction


1. Theory of Field Ionization (FI) and Field DesorptioN FD


1.1. FI Probability


1.2. Particle Supply


1.3. Minimum Distance for FI


1.4. Field-Induced Resonance States at a Surface


1.5. Theory of Field Desorption (FD) and Field Evaporation


1.5.1. Metal Field Anodes


1.5.2. Carbon Field Anodes


1.6. Field Electron Emission


2. FI and FD Techniques and Sources


2.1. General Design of FI Sources


2.1.1. Non-Focusing FI sources


2.1.2. Focusing FI Sources


2.1.3. Lens Systems


2.1.4. Fluctuation in FI Currents


2.2. Tips as FI Emitters


2.2.1. Methods for the Production of FI Tips


2.2.2. Measurement of Tip Radius and Shape Factor


2.2.3. Angular Distribution of FI Currents Emitted from Tips


2.2.4. FI Current-Voltage Curves for Tip Emitters


2.2.5. Threshold Field Strength


2.2.6. Heating of Point Anodes


2.3. Sharp Metal Edges as FI Emitters


2.4. Thin Wires as FI/FD Emitters


2.4.1. Production of Thin Wires for FI


2.4.2. Activation of Thin Wires for FI and FD


2.4.3. Structure of the Carbon Microneedles


2.4.4. FI Current-Voltage Curves of Activated Wires


2.4.5. Alternative Methods for Microneedle Production


2.5. Comparison of Tips, Sharp Metal Edges and Thin Wires


2.6. Design of Some FI/FD Sources


2.7. Pulsed FI Sources


2.8. FI Microscopes as Sources for Mass Spectrometers


2.8.1. FI Microscopes


2.8.2. Mass Analyses with Modified FI Microscopes


2.8.3. The Atom-Probe FI Microscope


2.9. Resolving Power of FI/FD Mass Spectrometers


2.10. Sample Loading Techniques for FD Wires


2.10.1. Emitter-Dipping Technique


2.10.2. Syringe Technique


2.11. Sensitivity of FI/FD Mass Spectrometers


2.12. Preparation and Recording of an FD Mass Spectrum


2.13. Automatic Emitter Emission Control, and Emitter Current Program for FD


3. High Field Surface Chemistry


3.1. Charge Distribution of Organic Ions in High Electric Fields


3.1.1. Quantum Mechanical Treatment


3.1.2. Semi-Classical Approximation


3.2. Field Dissociation of Molecular Ions


3.2.1. Classical Treatment


3.2.2. Quantum Mechanical Treatment


3.3. Bond Energies of Molecular Ions


3.4. Field Condensation and Multilayer Adsorption


3.4.1. Dependence of the Mean Free Path on the Field Strength


3.5. Ion Clusters


3.6. Appearance Potentials for Ion Formation in High Fields


3.7. Mechanisms of Reactions in Adsorbed Layers at High Fields


3.7.1. Field-Induced Chemisorption of Ions


3.7.2. Field-Induced Adsorption of Neutral Molecules


3.7.3. Surface Ions


3.7.4. Ion-Molecule Reactions with Surface Ions


3.7.5. Dehydrogenation of Paraffins


3.7.6. Proton Transfer Reactions in Adsorbed Layers without Surface Interaction


3.7.7. Proton Transfer Reactions in Adsorbed Layers with Surface Interactions


3.8. Multiply Charged Ions


3.9. Promotion of FI


3.10. Supplementary Notes


4. Kinetics and Mechanisms of Decomposition of Field Ions in the Gas Phase


4.1 Introduction


4.2. Calculation of the Decomposition Times


4.2.1. Tips, Thin Wires or Blades Used as Field Anodes


4.2.2. Determination of the Kinetic Energy eU* of Fragment Ions


4.2.3. Metastable Decomposition of Ions in the Space following the Counter-Electrode


4.2.4. Peak Shapes in the Single-Focusing Mass Spectrometer


4.3. Possible Elementary Mechanisms for Ion Decomposition in High Electric Fields


4.3.1. Field Dissociation


4.3.2. Tunneling of Radicals through Potential Barriers


4.3.3. Rotation of Molecular Ions


4.3.4. Field-Induced Statistical Decomposition


4.4. Statistical Decomposition in Weak Fields and in the Field Free Spaces of the Mass Spectrometer


4.5. Evaluation of the Reaction Rates


4.5.1. Determination of k(t) in the Space between the Emitter and the Counter-Electrode


4.5.2. Determination of k(t) for the Decay in the Ion-Retarding Electrodes of a Single-Focusing Mass Spectrometer


4.5.3. Determination of k(t) for the Decomposition of Ions in the Field Free Spaces of Double-Focusing Mass Spectrometers


4.6. Normalized Rates of Some Decomposition Processes in the Time Range of about 3 x 10-11 to 2 x 10-6 sec


4.7. Mechanisms of Some Selected Unimolecular Reactions of Organic Ions


4.7.1. Hydrogen Randomization


4.7.2. Elimination of H2O from n-Hexanol


4.7.3. Formation of Tropylium Ions


4.7.4. Kinetics of Competing Rearrangement Reactions and Direct Bond Cleavages


4.8. Temperature Dependence of FI Mass Spectra


4.9. Determination of the Energy Distribution P(E) of Field-Ionized Molecules


4.10. Combination of Field Ionization Kinetics with Other Mass Spectrometric Methods


5. Qualitative and Mixture Analysis with FI and FD Mass Spectrometry (MS)


5.1. Introduction


5.2. Qualitative Analysis with an FI Mass Spectrometer


5.3. Analysis of Mixtures using FI MS


5.3.1. Analysis of Low Boiling Hydrocarbon Mixtures


5.3.2. Analysis of Heavy Petroleum Fractions (Paraffin Waxes)


5.3.3. Analysis of Multicomponent Polar and Unpolar Organic Mixtures


5.3.4. Analysis of the Products of Pyrolysis of Technical Polymers


5.4. Qualitative Analysis with the FD Mass Spectrometer


5.4.1. Introduction


5.4.2. Comparison of Mass Spectra taken with EI, CI, FI or FD Sources


5.4.3. Application of FD MS in Biochemistry


5.4.4. Application of FD MS in Medicine


5.4.5. FD MS of Salts


5.4.6. FD Mass Spectra of Polymers


5.4.7. FD MS in Environmental Analysis


5.4.8. Quadrupole FD MS


5.5. Quantitative Analysis of Mixtures with FD MS


5.5.1. The Method of Internal Standards


5.5.2. High Pressure Liquid Chromatography and FD MS

References

Index

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