Accurate Moessbauer line-shape measurements including interference in 182W, 183W, 191Ir, and 159Tb

We have made precise final state interference measurements using very intense Moessbauer sources and an exact line-shape analysis. Two transitions in tungsten metal, as well as one in iridium metal and one in terbium oxide, have been studied. The interference parameters 100β found are -1.3(3) for the 99.1-keV transition in 183W, -1.2(1) for the 100.1-keV transition in 182W, -0.71(8) for the 129.4-keV transition in 191Ir, and -0.48(5) for the 58.0-keV transition in 159Tb. All values agreed with theory to within error. Our measurement of 1.16(2) cm/s for the 191Ir linewidth agrees with other Moessbauer measurements and shows no indication of hyperfine broadening, but disagrees with some non-Moessbauer measurements reported in the literature. The tungsten and terbium transitions also show no signs of broadening or splitting