Neutron Radiation
Part-4.qxd 6/11/07 4:31 PM Page 242 242 Radioactivity Hall of Fame—Part IV The energy of bonding between the carbon and iodine atoms is about 2 eV, which is higher than the neutron recoil energy. Consequently, the rupture of this bond is due to the gamma recoil when the 128I undergoes gamma emission upon deexcitation after neutron capture. Some atoms of 128I could recombine with the free ethyl group and even exchange with some stable atoms of 127I, but if these processes are slow and, if these processes are further reduced by the addition of water or even alcohol to dilute the organic phase, the precipitate of radioactive inorganic iodide proceeds yielding a highly enriched radioactive 128I with minimal 127I. The Szilard–Chalmers process remains to this day a very practical application to the isolation of high specific activity radioactive sources from the medium in which the radionuclide sources were synthesized. A few examples taken from the literature are the isolation of high specific activity radioiso- topes after cyclotron production (Birattari et al., 2001; Bonardi et al., 2004; ), the preparation of high specific activity 64Cu for medical diagnosis (Hetherington et al., 1986), high specific activity radio- hafnium complexes (Abbe and Marques-Netto, 1975; Marques-Netto and Abbe, 1975), high specific activity 51Cr (Green and Maddock, 1949; Harbottle, 1954), high specific activity 56Mn (Zahn, 1967a,b), high specific activity 156Re (Jia and Ehrhardt, 1997), high specific activity 166Ho (Zeisler and Weber, 1998), high specific activity radioisotopes of tin (Spano and Kahn, 1952), and the concentration of high specific activity of the radioisotopes of Groups IV and V elements (Murin and Nefedov, 1955), etc.
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