Applications of Pulse Radiolysis for the Study of Short-Lived Sulphur Species
The first successful observations of free radical intermediates by spectroscopic techniques were made by Norrish and Porter using flash photolysis. Pulse radiolysis is the radiation-chemical analogue of flash photolysis. In it free radicals are created by the deposition of energy from a transient beam of high energy (0.6–10 MeV) electrons. These lose energy to electrons in the molecular orbitals of the target material due to repulsive coulombic interactions. The discrete energy losses result in excitations or ionizations of the molecules.1 In water ionization dominates, with an average distance of about 100 nm between successive events. Secondary electrons produced in these ionizations have varying energies. They too cause ionization and excitation. Those of low energy (100 eV) deposit their energy within a relatively small volume, creating what is commonly called a spur with a number of ions, electrons, and free radicals in relatively close proximity. The distributions of radicals per spur (or of spur sizes) depends on the initial energy of the primary electrons and the medium irradiated. For 1 MeV electrons in water at 25 °C, about half the spurs contain only one ion pair, while for the others the number of reactive species varies up to about six.
KeywordsRadical Cation Lipoic Acid Bond Dissociation Energy Flash Photolysis Pulse Radiolysis
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- 1.I.G. Draganic and Z.D. Draganic, The Radiation Chemistry of Water, Academic, Press, New York (1971).Google Scholar
- 2 a.
- 2 b.
- 2 c.
- 3 a.
- 3 b.
- 3 c.
- 5 a.M. Bonifacic, H. Möckel, D. Bahnemann, and K.-D. Asmus, J. Chem. Soc. Perkin Trans. I1 675 (1975).Google Scholar
- 5 b.
- 5 c.
- 7 a.
- 7 b.
- 7 c.
- 8 a.J.E. Packer, in: “The Chemistry of the Thiol Group”, Part 2, S. Patai, ed., Wiley, London, Chapter 11 (1974).Google Scholar
- 8 b.C. von Sonntag and H.P. Schuchmann, in “Chem. Ethers, Crown Ethers, Hydroxyl Groups and Their Sulphur Analogues”, S. Patai, ed., Wiley, Chichester, England, Vol. 2 (1980).Google Scholar
- 9.M.S. Akhlaq, C. von Sonntag, Z. Naturforsch. C.: Biosci. 42: 134 (1987).Google Scholar
- 10.M. Bonifacic and K.-D. Asmus, J. Chem. Soc. Perkin Trans. II 1805 (1986).Google Scholar
- 11 a.
- 11 b.
- 11 c.