Coherent quantum diffusion of muonium in a highly disordered medium

Abstract

We have investigated the quantum diffusion of interstitial muonium atoms in solid mixtures of methane with krypton at temperatures from 10 to 90 K. At sufficiently high concentrations of Kr (above about 25%) the frustration of anisotropic molecular interactions produces an orientational glass phase. Even in this highly disordered medium, muonium exhibits coherent quantum tunneling dynamics with a bandwidth only slightly reduced with respect to that in pure solid methane. The muonium diffusion is shown to be long range rather than local. © 2002 Elsevier Science B.V. All rights reserved.