On the Electronic Structure of Hydrogen in Metals in the Light of Muon Knight Shift Measurements

Abstract

The Knight shift of positive muons has been measured up to now in 18 elemental nontransition (simple) metals and in the transition metals V, Nb, Ta, Pd and Ni. In addition data are available from the hydrogen storage system LaNi5Hx. Except for the latter substance all data correspond to the limit of zero hydrogen concentration. Since the bare muon like the proton carries a single elementary positive charge and introduces a strongly disturbing Coulomb potential into the host lattice it is expected that both particles induce the same local electronic structure, subject perhaps to isotope effects. The total Knight shift, consisting of paramagnetic and diamagnetic contributions, allows thereby to test certain features of the local electronic structure. The data will be compared with existing predictions obtained from jellium, cluster and band structure calculations. Some interesting systematics of the data and possible isotope effects will be pointed out.