Origin of the residual polarization in muon chemistry studies of solvent mixtures

Abstract

When polarized positive muons are stopped in common chemicals, there is always a residual polarization due to the fraction of muons which immediately enter diamagnetic states. This fraction varies considerably, being 0.17, 0.62, and 1.0 in benzene, cyclohexane, and carbon tetrachloride, respectively. In order to examine the mechanism by which it arises, mixtures of benzene with cyclohexane and carbon tetrachloride were studied. The results indicate that incorporation into diamagnetic species occurs mainly in a one-step intramolecular process, which is consistent with the hot model. Competitive secondary reactions are involved to only a limited extent, and the spur model is evidently inoperative. The results also suggest that the average energy range over which the hot process occurs is comparable to the energy lost during a thermalizing encounter with a molecule.