Radiation and Fragmentation

The effects of radiation on phosphorus compounds may be chemical, in which case bonds are broken, and ions, radicals or new molecules are formed, or they may be physical, such as the creation of holes (vacancies) or other defects in the crystal lattice. The effects of high-energy radiation on phosphorus compounds are important since x-rays and y-rays are used in food preservation, and organophospho-rus esters are used in the complexing of metals in the purification of nuclear fuels. The importance of the effects on phosphate esters present in living systems has long been recognised. 

Neutron bombardment produces transformation of the nucleus—a process which is invariably accompanied by the emission of electrons, y-rays or particles of some kind. These in turn will lead to chemical fragmentation. 

Diphosphorus P2 molecules are the primary species evaporating from red phosphorus, but are stable only at high temperatures or low pressures (Chapter 4.1). Various unstable ion fragments P2 P3 P4 P8 P P4 P P2 etc. are obtained by electron bombardment of red phosphorus in a mass spectrometer. Positive ion fragments are also obtained by arc or spaik excitation of red phosphorus. 

The great majority of fragments are cations, and those of highest molecular weight tend to be produced in greatest abundance, although this feature is influenced by the molecular complexity and the excitation technique employed. 

FIGURE 13.11 Mass spectral fragmentation of PI13P (part), (a) (b) 

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