Pressure-dependent muonium kinetics in aqueous solution

Muonium decay rates have been measured as a function of pressure for the first time in condensed matter. The reactions of muonium with NO-3 and MnO-4 were found to have activation volumes of - 7.1 ± 1.5 cm3 mol-1 and + 3.1 ± 1.6 cm3 mol-1, respectively. These volumes are compared with -5 cm3 mol-1 and +2 cm3 mol-1 for activated and diffusion-controlled reactions of hydrogen atoms. The results support the concept of local order of the water molecules around each H or Mu atom in solution. (author)