Evidence for the formation of ion clusters spurs

It has been suggested above that, for lightly ionising radiation, the spurs are separated very widely from each other when the radiation does rate is small. The reaction of the ions and radicals within a spur leads to some molecular products, for instance in water both molecular hydrogen and hydrogen peroxide are formed [413] and some ( ) of the reactions involved are listed below. 

Usually, the average concentration of a reactive species such as OH or H is not directly observed in pulse radiolysis experiments, partly because the timescale of spur reactions is so short ( 10 ns) that most spur reactions have occurred during the radiation pulse which produces these species and partly because these species are very difficult to monitor on such a timescale. Instead, solutes are often added to water prior to radiolysis and the quantity of products formed by reaction of the solute 

Jonah et al. [178] found that the fluorescence emitted by 9,10-diphenyl-anthracene (or by p-terphenyl) in cyclohexane solution after photostimulation with Cerenkov radiation both grew-in and decayed more rapidly than when the solution was pulse-radiolysed (see Fig. 34). The delay in the formation of the aromatic excited state ( 0.5 ns) was attributed to the slowness of charge capture and of diffusion together of ions to form an excited state (Sect. 3.4). 

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