Trapped atoms and radicals in rigid solvents

Abstract
A number of very reactive radicals and atoms prepared by photolysis in rigid hydrocarbon glasses at the temperature of liquid nitrogen have been detected by their absorption spectra. Thus ethyl iodide dissociates to iodine atoms which only recombine to give I$_{2}$ when the glass is softened. Similarly CS$_{2}$ and ClO$_{2}$ give CS and ClO which can be detected spectroscopically in the frozen glass. Toluene and other benzyl derivatives yield the benzyl radical, and the spectra of a number of similar unstable aromatic radicals have been recorded for the first time. Most of these radicals have lifetimes of less than 1 ms at comparable concentrations in the gas phase or in ordinary solutions, but have been observed for many hours in the rigid glass. The method should be of general applicability for the study of the primary products of photochemical or radiation chemical processes.