Chemical and magnetic properties of muonic free radicals in solutions of styrene in benzene

Abstract

Implantation of positive muons in solutions of styrene in benzene creates free radicals which are observed and studied by the muon spin rotation (µ.s.r.) technique. Muonium-substituted phenylethyl and cyclohexadienyl radicals are identified, and relative rate constants for their formation deduced from the concentration dependence of the µ.s.r. amplitudes. There seems to be an indication from the phases of the phenylethyl signals that the precursor may be diamagnetic. Possible broadening mechanisms of the µ.s.r. linewidths are surveyed and the means of distinguishing them through their different dependences on magnetic field, temperature and concentration are demonstrated. The linewidth of the muonic phenylethyl radical provides a direct measurement of the rate of dimerization in styrene.