The Study of Fast Processes and Transient Species by Electron Pulse Radiolysis

This volume contains the lectures given at the NATO Advanced Study Institute "The Study of Fast Processes and Labile Species in Chemistry and Molecular Biology Using Ionising Radiation" held in Capri, Italy, September 7-l8th 1981. The aim of the Institute was to summarise the present position of the use of pulsed ionising radiation in chemical and biological chemical research. For background an outline of the basic radiation chemistry and physics involved and descriptions of techniques and equipment in current use was presented. It was followed by comprehensive coverage of the state of this research to date in various areas of chemistry and biological chemistry. It was hoped to demonstrate to researchers not directly involved with ionising radiation how this technique is now at a stage in its development where it can have wider applications in various branches of chemistry and biology. The fifty participants did indeed form a wide spectrum of scientific interest covering inorganic, physical and organic chemistry, molecular physics, molecular biology, radiobiology and bacteriology. They also represented a wide variety of countries viz. Belgium, China, Denmark, France, Germany, Greece, Holland, Hungary, India, Italy, Poland, Turkey, U.S.A., U.K. and Yugoslavia.

Contenu

Absorption of Energy From Ionizing Radiation.- 1. X-rays and ?-rays.- (a) Photoelectric effect.- (b) Compton effect.- (c) Pair production.- 2. Electrons.- (a) Excitation and ionisation of molecules.- (b) Emission of radiation.- (c) Electron range.- (d) Low energy electrons.- 3. Heavy Positive Particles.- (a) High energy.- (b) Low energy.- 4. Neutrons.- References.- Basics of Radiation Chemistry.- Spacial Distribution and Reaction Kinetics.- 1. Charge Particle Tracks and Track Densities.- 2. Spur Reactions.- 3. Non-Homogeneous Kinetics.- Time Scale of Events in a Liquid.- 1. Development.- 2. Summary of Time Scale.- References.- Sources of Pulsed Radiation.- 1. Introduction.- 2. Types of Pulsed Radiation Sources.- 2.1. Microwave linear accelerators.- 2.2. Febetrons.- 2.3. Other sources of pulsed radiation.- 3. Physical Dosimetry for Pulses Sources.- References.- Chemical Dosimetry of Pulsed Electron and X-Ray Sources in the 1-20 MeV Range.- 1.1. Units of Absorbed Dose.- 1.2. Units of Radiation Chemical Yield.- 2.1. Principles of Chemical Dosimetry.- 2.2. The Ferrous Sulphate or Fricke Dosimeter.- 2.3. The "Super Fricke Dosimeter".- 2.4. Other Dosimeters Suitable for High Intensity Pulsed Sources.- 3.1. Dosimetry by the Measurement of Fugitive Species.- 3.2. Sources of Error.- 1. Correction due to pulse duration.- 2. Correction for response time of system.- 3.3. The Thiocyanate Dosimeter.- 3.4. The Hydrated Electron Dosimeter.- 3.5. The Ferrocyanide Dosimeter.- References.- Optical Monitoring Techniques.- 1. General Considerations.- 2. Optical Systems.- 2.1. Lenses.- 2.2. Mirrors.- 2.3. Light-Sources.- 2.4. Monochromators.- 3. Monitoring Techniques.- 3.1. Photodetectors.- 3.2. Photomultipliers.- 3.3. Photodiodes.- 3.4. Detector circuits.- References.- Conductivity Monitoring Techniques.- Electrical Principles.- Limitations.- Experimental Set-ups.- Chemical Examples.- Conclusion.- References.- Polarography Monitoring Techniques.- Experimental Section.- Examples.- Conclusion.- References.- The Microwave Absorption Technique For Studying Ions and Ionic Processes.- Experimental.- General.- Circuit components.- Irradiation cells.- Irradiation conditions.- Data Reduction.- Reflection cell.- Resonant cavity cell.- The yield-mobility product.- Application and Comparison with other Techniques.- References.- EPR and NMR Detection of Transient Radicals and Reaction Products.- Time Resolved EPR.- Pulsed EPR.- Time resolved spectra.- Time sweep.- Free induction decay.- NMR in Radiation Chemistry.- References.- Radical Ions and Excited States in Radiolysis. Optically Detected Time Resolved EPR.- Method, Results and Discussion.- References.- Light Scattering Techniques for Investigation of Transients Produced in Electron Pulse Radiolysis.- Rayleigh Scattering.- Raman Scattering.- Background.- Origin of resonance enhancement.- Experimental.- Pulse radiolysis and TR3 detection.- Current activity.- References.- Data Acquisition and Analysis in Pulse Radiolysis Part is Control, Digitization, and Analysis.- 1.0. Introduction.- 2.0. Timing and Control.- 3.0. Digitisation of the Transient Signal.- 3.1. Oscilloscopes.- 3.2. Electronic digitiser.- 3.3. Diode matrix technique.- 3.4. Streak cameras.- 3.5. Pulse-probe technique.- 3.6. Counting methods.- 3.7. Computer as digitiser.- 4.0. Data Processing and Analysis.- 4.1. Initial data processing.- 4.2. Simple linear fitting.- 4.3. Iterative linear regression.- 4.4. Direct solution of kinetic equations.- 4.5. Deconvolution.- 4.6. Statistical considerations.- 5.0. Conclusion.- References.- Data Acquisition and Analysis in Pulse Radiolysis Part II: Computerization.- 1.0. Introduction.- 2.0. Historical Survey.- 2.1. The computer revolution.- 2.2. Computers in pulse radiolysis.- 3.0. Techniques of Laboratory Computerisation.- 3.1. Computer hardware.- Minicomputers.- Microcomputers.- 3.2. Hardware Interfacing.- Camac.- GPIB.- S-100 Bus.- Ethernet.- 3.3. Operating systems.- 3.4. Programming languages.- 4.0. Some General Aspects of Design and Implementation.- 4.1. Flexibility.- 4.2. Ease of use.- 4.3. Manual control option.- 4.4. How much computerisation?.- 5.0. Conclusion.- References.- Rapid Techniques for Correcting Nanosecond Kinetic Traces for Convolution Error.- 1.0. Introduction.- 2.0. Separation of the Convolution Integral.- 3.0. Model Excitation Response Function.- 4.0. Discussion.- 5.0. Examples.- 6.0. Conclusion.- References.- Basic Radiation Chemistry of Liquid Water.- 1. Introduction.- 2. Primary Events.- 3. Experimental Evidence for Spurs.- 4. Yields of the Primary Species.- 4.1. Yields in neutral solution.- 4.2. Dependence on pH.- 5. Initial Yields.- 6. Properties of the Primary Radicals.- 6.1. Hydrated electron.- 6.2. Hydrogen atom.- 6.3. Hydroxy1 radical.- 6.4. Perhydroxyl radical.- 7. Water Radiolysis as a Chemical Tool.- 7.1. Oxidising conditions.- 7.2. Reducing conditions.- 8. Concluding Remarks.- References.- Applications of Water Radiolysis in Inorganic Chemistry.- 1. Introduction.- 2. Inorganic Free Radicals.- 3. Non-metallic Compounds.- 3.1. Oxyhalogen ions.- 3.2. Borohydride ion.- 4. Aquo-metal Ions in Unusual Oxidation States.- 5. Lanthanides and Actinides.- 6. Transition Metal Complexes.- 6.1. Electron transfer.- 6.2. Coordinated free radicals.- 6.3. Aquation of transition metal complexes.- 6.4. Change in symmetry.- 7. Concluding Remarks.- References.- Application of Pulse Radiolysis to the Study of Aqueous Organic Systems.- Reactions of OH, e-aq and H.- Hydroxyl radicals.- Hydrated electrons.- Hydrogen atoms.- Design of Experiments.- Radicals formed from OH reactions.- Radicals formed from e-aq reactions.- Radicals formed from H reactions.- Acid-base properties.- Errors.- Free Radicals Formed from Organic Compounds.- Hydrocarbons.- Halides.- Alcohol and carbonyl compounds.- Sulphur compounds.- References.- Application of Pulse Radiolysis to the Study of Molecules of Biological Importance.- One Electron Reduction Potentials.- Quinones.- Carbohydrates.- Amino Acids and Peptides.- Pyridine Compounds.- Flavins.- Haem and Haemoproteins.- Vitamin B12.- Excited States.- References.- Structure and Dynamics of Paramagnetic Transients By Pulsed EPR and NMR Detection of Nuclear Resonance.- Time Resolved EPR.- NMR Detection of Nuclear Resonance.- CIDNP and CIDEP Contributions.- References.- Transients in Low Temperature Aqueous Glasses.- 1. The Glassy State.- 2. Techniques Used in Matrix Isolation Studies.- Recombination Luminescences.- Electro Luminescences.- 3. Radiation Chemistry in Glassy Matrices.- 4. Examples of Aqueous Glasses.- 4.1. Pure ice.- 4.2. Acid glasses.- 4.3. Alkaline glasses.- 4.4. Salt glasses.- 4.5. Ethylene glycol-water gl…