Formation of the muoniated ethyl radical in the gas phase

The precession signals of the muoniated ethyl radical have been studied as a function of ethene pressure in pure ethene, ethene/nitrogen mixtures and ethene/helium mixtures. The purpose was to investigate the kinetics and mechanism of the radical formation process. It is possible to fit the signal amplitudes with a model involving a single reaction step-Mu addition to ethene. However, the rate constant deduced from the model fit is significantly higher than the literature value for a thermal reaction, as determined by direct study of Mu decay in low partial pressures of ethene. The conclusion is that at partial pressures above 1 bar the reaction occurs before the incoming (beam) muons are fully thermalized. (C) 2002 Elsevier Science B.V. All rights reserved.