Mortemousque, P.ABerger, S.Sekiguchi, T.Culan, C.Elliman, RobertItoh, K.M.2015-12-100163-1829http://hdl.handle.net/1885/70320Bismuth donors ion-implanted in 28Si and natSi are studied using magnetic resonance spectroscopy based on spin-dependent recombination. The hyperfine clock transition, at which the linewidth is significantly narrowed, is observed for the bismuth donors. The experimental results are modeled quantitatively by molecular orbital theory for a coupled pair consisting of a bismuth donor and a spin-dependent recombination readout center, including the effect of hyperfine and Zeeman interactions.Author/s retain copyright201410.1103/PhysRevB.89.1552022015-12-10