REFERENCES 67 



It is convenient and informative to consider hydrated ions as complex 

 molecules. As Franck has pointed out (28), the photochemical and 

 radiochemical properties of such ions are to a large extent determined by 

 the acts of internal conversion which they can undergo. For example, 

 when a hydrated ferrous ion absorbs a photon, an electron is ejected 

 into the shell of water molecules which surround the central ion. The 

 resulting electronically excited complex molecule can undergo a process 

 of internal conversion and so produce a complex molecule with a large 

 amount of oscillational energy. It may lose this energy as heat to the 

 solvent or, less probably, eject a hydrogen atom leaving a stable hydroxy 

 ferric complex ion. As may be predicted on the basis of this mechanism, 

 the absorption of more energetic photons increases the probability of 

 the escape of the hydrogen atom. High concentrations of oxidizing 

 agents also favor the production of the ferric ion. It is an interesting 

 fact, and one which is consistent with a more detailed analysis of this 

 reaction, that the quantum yield of oxygen production due to the 

 illumination of a solution containing ferric ions is less than 10~^, but in 

 the presence of certain reducing agents the photochemical reduction of 

 ferric ion approaches unity. 



When an alpha particle is absorbed in liquid water a concentrated 

 column of ions is formed. Momentarily, the core of this column consists 

 of positive ions surrounded by a cylindrical shell of negative ions pro- 

 duced by electrons which were ejected with relatively high velocities. 

 The localized concentrations of hydronium and hydroxyl ions which are 

 so produced exceed the concentrations of the same ions which are 

 obtainable in even concentrated basic or acidic solutions. Franck has 

 recently suggested the interesting idea that these short-lived regions 

 containing high concentrations of hydroxyl or hydronium ions could well 

 be responsible for the denaturation of a protein molecule or the breaking 

 of a chromosome chain which suffers a near miss by an alpha particle. 



REFERENCES 



1. Franck, J., and H. Sponer, Contribution a Vetude de la structure moleculaire, p. 169, 

 Liege, 1948. 



2. Eyring, H., J. Hirschfelder, and H. S. Taylor, /. Chem. Phys., 4: -179, 1936. 



3. Burton, M., /. Phys. Colloid Chem., 51: 611, 1947. 



4. Bragg, W. H., Phil. Mag., 13: 333, 1907. 



5. LeBlanc, M., Z. physik. Chem., 85: 511, 1913. 



6. Lind, S. C, The Chemical Effects of Alpha Particles and Electrons, Chemical 

 Catalog Co., 1928. 



7. Mund, W., Ann. soc. sci. Bruxelles, B51, 1931. 



