ACCURATE MOSSBAUER LINE-SHAPE MEASUREMENTS INCLUDING INTERFERENCE IN W-182, W-183, IR-191, AND TB-159

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