Reduced Yield in Dilute Solutions Irradiated at Very High Dose Rates

Abstract

Irradiation of dilute methylene blue solutions with a high-intensity electron beam producing 104 roentgens/ microsecond pulse gives less radiation-induced decolorization than the same dose given at lower rates. This decrease is to be expected from the mechanism involving H and OH radicals usually used to explain ionizing radiations effects on dilute solutions. On the basis of this mechanism, a simple theory of rate dependence is derived. It is concluded that the OH radical is extremely likely to react when it collides with a methylene blue molecule, the observed reaction rate being somewhat between 25 and 100% of the maximum possible if a reaction took place on every encounter.