Chemical effects in negative muon capture in some ionic and covalent solids and ionic aqueous solutions

Abstract

Muonic x-ray spectra have been measured for target sequences including graphite, diamond, their boron-nitride counterparts, three organic compounds, ice and water, eight oxides of metals, alkali halides in aqueous solution and alkali chlorides in anhydrous crystalline form, and calcium and titanium hydrides. Comparisons are made of Lyman-series intensity patterns, and relative muon capture probabilities in the constituent elements of compounds are compared with ''Z-law'' relation. The Lyman intensities of the C and N in the low-Z targets are found to exhibit two kinds of pattern, one with relatively weak higher-series members characterizing the diamond and graphite structures, and one with stronger higher-series members characterizing the other (hydrogen-containing) compounds. There is some evidence that the latter intensity behavior applies to the aqueous ions as well. For the oxide sequence, increasing covalency appears to correlate with increasing muon capturing ability of the metal element and with increasing intensity of the higher Lyman members for both the metal element and the oxygen. Effective relative muon-capture cross sections have been obtained for aqueous alkali and halide ions. (AIP)