In 1897, J. J. Thompson "discovered" the electron. Around the same time, Mikhail Semenovich Tswett presented a lecture on his novel method of dynamic adsorption analysis, soon known as chromatography. These achievements laid the groundwork for James Lovelock, who fifty years later observed the perturbation of ion currents by the reactions of thermal electrons with molecules. Lovelock’s invention of the Electron Capture Detector (ECD) created an instrument for measuring the properties of these compounds and the reactions involved.
Today, with the ECD in widespread use and many molecular affinities and rate constants for thermal electron attachment measured, it is an appropriate time to review the techniques for studying the reactions of thermal electrons with molecules. The Electron Capture Detector and the Study of Reactions with Thermal Electrons provides just such a timely review, as well as a thorough evaluation of the results attained thus far. In addition, this text:
- Summarizes other methods for studying reactions of thermal electrons with molecules
- Reviews electron affinities and thermodynamic and kinetic parameters of atoms, small molecules, and large organic molecules obtained using various techniques
- Describes ECD applications in analytical chemistry, physical chemistry, and biochemistry
- Provides an Appendix with electron affinities in tabular form
With coverage ranging from the history of the electron to definitions and nomenclature, experimental procedures, and modern applications, the scope of this text is greater than any other available book on the subject of negative ions. Professionals and graduate students in analytical, physical, and environmental chemistry can now turn to The Electron Capture Detector and the Study of Reactions with Thermal Electrons for a comprehensive guide to the theory and practice of ECD.
1. Scope and History of the Electron.
1.1 General Objectives and Organization.
1.2 General Scope.
1.3 History of the Electron.
2. Definitions, Nomenclature, Reactions, and Equations.
2.2 Definition of Kinetic and Energetic Terms.
2.3 Additional Gas Phase Ionic Reactions.
2.4 Electron Affinities from Solution Data.
2.5 Semi–Empirical Calculations of Energetic Quantities.
2.6 Herschbach Ionic Morse Potential Energy Curves.
3. Thermal Electron Reactions at the University of Houston.
3.1 General Introduction.
3.2 The First Half–Century, 1900 to 1950.
3.3 Fundamental Discovery, 1950 to 1960.
3.4 General Accomplishments, 1960 to 1970.
3.4.2 The Wentworth Group.
3.4.3 Stable Negative–Ion Formation.
3.4.4 Dissociative Thermal Electron Attachment.
3.4.5 Nonlinear Least Squares.
3.5 Milestones in the Wentworth Laboratory and Complementary Methods, 1970 to 1980.
3.6 Negative–Ion Mass Spectrometry and Morse Potential Energy Curves, 1980 to 1990.
3.7 Experimental and Theoretical Milestones, 1990 to 2000.
3.8 Summary of Contributions at the University of Houston.
4. Theoretical Basis of the Experimental Tools.
4.2 The Kinetic Model of the ECD and NIMS.
4.3 Nondissociative Electron Capture.
4.4 Dissociative Electron Attachment.
4.5 Electron Affinities and Half–Wave Reduction Potentials.
4.6 Electron Affinities and Ionization Potentials of Aromatic Hydrocarbons.
4.7 Electron Affinities and Charge Transfer Complex Energies.
5. Experimental Procedures and Data Reduction.
5.2 Experimental ECD and NICI Procedures.
5.3 Reduction of ECD Data to Fundamental Properties.
5.3.2 Acetophenone and Benzaldehyde.
5.3.3 Benzanthracene, Benz[a]pyrene, and 1–Naphthaldehyde.
5.3.4 Carbon Disulfide.
5.3.6 Consolidation of Electron Affinities for Molecular Oxygen.
5.4 Reduction of Negative–Ion Mass Spectral Data.
5.5 Precision and Accuracy.
5.6 Evaluation of Experimental Results.
6. Complementary Experimental and Theoretical Procedures.
6.2 Equilibrium Methods for Determining Electron Affinities.
6.3 Photon Techniques.
6.4 Thermal Charge Transfer Methods.
6.5 Electron and Particle Beam Techniques.
6.6 Condensed Phase Measurements of Electron Affinities.
6.7 Complementary Theoretical Calculations.
6.7.1 Atomic Electron Affinities.
6.7.2 Polyatomic Molecules.
6.8 Rate Constants for Attachment, Detachment, and Recombination.
7. Consolidating Experimental, Theoretical, and Empirical Data.
7.2 Semi–Empirical Quantum Mechanical Calculations.
7.3 Morse Potential Energy Curves.
7.3.1 Classification of Negative–Ion Morse Potentials.
7.3.2 The Negative–Ion States of H2.
7.3.3 The Negative–Ion States of I2.
7.3.4 The Negative–Ion States of Benzene and Naphthalene.
7.4 Empirical Correlations.
8. Selection, Assignment, and Correlations of Atomic Electron Affinities.
8.2 Evaluation of Atomic Electron Affinities.
8.3 Mulliken Electronegativities.
8.4 Electron Affinities of Atomic Clusters.
9. Diatomic and Triatomic Molecules and Sulfur Fluorides.
9.2 Diatomic Molecules.
9.2.1 Electron Affinities and Periodic Trends of Homonuclear Diatomic Molecules.
9.2.2 Electron Affinities and Morse Potential Energy Curves: Group VII Diatomic Molecules and Anions.
9.2.3 Electron Affinities and Morse Potential Energy Curves: Group VI Diatomic Molecules and Anions.
9.2.4 Electron Affinities and Morse Potential Energy Curves: Group IA and IB Homonuclear Diatomic Molecules and Anions.
9.2.5 Electron Affinities and Morse Potential Energy Curves: NO and NO( ).
9.3 Triatomic Molecules and Anions.
9.4 Electron Affinities and Morse Potential Energy Curves: Sulfur Fluorides and Anions.
10. Negative Ions of Organic Molecules.
10.2 Electron Affinities and Potential Energy Curves for Nitrobenzene and Nitromethane.
10.3 Electron Affinities Determined Using the Magnetron, Alkali Metal Beam, Photon, and Collisional Ionization Methods.
10.3.1 Electron Affinities Determined Using the Magnetron Method.
10.3.2 Electron Affinities Determined Using the AMB Method.
10.3.3 Electron Affinities Determined Using Photon Methods.
10.3.4 Electron Affinities Determined Using Collisional Ionization Methods.
10.4 Electron Affinities Determined Using the ECD, NIMS, and TCT Methods.
10.4.1 Electron Affinities of Aromatic Hydrocarbons by the ECD Method.
10.4.2 Electron Affinities of Organic Carbonyl Compounds by the ECD Method.
10.4.3 Electron Affinities of Organic Nitro Compounds the ECD and TCT Methods.
10.5 Electron Affinities of Charge Transfer Complex Acceptors.
10.6 Substituent Effect.
11. Thermal Electrons and Environmental Pollutants.
11.2 Alkyl Halides.
11.2.1 Morse Potential Energy Curves.
11.2.2 Experimental Activation Energies.
11.2.3 Alkyl Fluorocompounds.
11.2.4 Electron Affinities of the Alkyl Halides.
11.3 Aromatic Halides.
11.3.1 Electron Affinities of Fluoro– and Chlorobenzenes.
11.3.2 Electron Affinities from Reduction Potentials and CURES–EC.
11.3.3 Negative–Ion Mass Spectra and Electron Affinities.
11.4 Negative–Ion Mass Spectrometry.
11.5 Calculation of the ECD and NIMS Temperature Dependence.
12. Biologically Significant Molecules.
12.2 Electron Affinities of Purines and Pyrimidines.
12.2.1 Predictions of Electron Affinities.
12.2.2 Electron Affinities from Reduction Potentials.
12.2.3 Gas Phase Measurements of Electron Affinities.
12.2.4 Theoretical Electron Affinities.
12.3 Electron Affinities of Biological Molecules from Reduction Potentials.
12.4 Gas Phase Acidities of Nucleic Acids.
12.5 Morse Potential Energy Curves for Thymine and Cytosine.
12.6 Gas Phase Acidities and Electron Affinities of the Amino Acids.
12.7 The Calculation of the ECD and NIMS Temperature Dependence.
12.8 Electron Affinities of AT AU and GC.
12.9 Radiation Damage in DNA.
I Glossary of Terms, Acronyms, and Symbols.
II Structures of Organic Molecules.
III General Least Squares.
IV Tables of Evaluated Electron Affinities.
Table A1.1 Atoms.
Table A1.2 Main Group Homonuclear Diatomic Molecules.
Table A2.1 and A2.2 CH Molecules.
Table A2.3 and A2.4 CHX Molecules.
Table A3.1 and A3.2 CHNX Molecules.
Table A4.1 and A4.2 CHO Molecules.
Table A4.3 and A4.4 CHOX Molecules.
Table A5.1 and A5.2 CHON Molecules.
Table A5.3 and A5.4 CHONX Molecules.
Table A6.1 Bergman Dewar set.
Table A6.2 Values Different from NIST Values (from Tables A2.1 to A5.4).
Table A6.3 Unpublished or Updated Gas Phase Values not in NIST Tables.
Table A6.4 Values for Adenine, Guanine, Cytosine, Uracil, Thymine, and Their Hydrates.
Table A6.5 Values for Charge Transfer Complex Acceptors not in NIST Tables.
Table A6.6 Values for Chlorinated Hydrocarbons from Reduction Potentials and CURES–EC.
Table A6.7 Values for Biological Compounds from Reduction Potentials.