Search for hyperfine anomaly and quadrupole interaction of Os in Fe

Abstract

the equation. vl/v 2 = (1 + ~A 2)(I.t~Ijl.t2I ~ ) where v is the magnetic hyperfine splitting frequency, # the nuclear moment and I the spin. The iron lattice is ideal for the study of hfa of heavy nuclei because a substitutional atom is at a site of cubic symmetry in a large (= 1 MG) hyperfine field, eg the combination of NMR, NMR/ON and TDPAC has been used to find the hfa for W and Au in an iron host [1,2]. NMR measurements at 4.2 K were made on iron foils containing 1-0.005% of 189Os (I = 3/2) and 187Os (I = 1/2). The Os NMR frequencies were found to be only weakly dependent on concentration and extrapolated to (371.0 _+ 0.1) MHz and (118.18 _ 0.002) MHz for 189Os and lS7Os respectively, from which we find 187A189 = 0.0196 _ 0.0004. The hfa for Os is therefore an order of magnitude less than for W [1] unless the published nuclear moments also contain a contribution from the hfa. Unlike 197Au in iron [2] the 189Os NMR spectrum did not exhibit satellite lines so only a limiting value of the quadrupole interaction could be deduced.