Shape coexistence inTl189

High spin states of ${}_{}{}^{189}{}_{}{}^{}\mathrm{Tl}$ have been populated through the fusion-evaporation reactions ${}_{}{}^{169}{}_{}{}^{}[_{}^{24}{}_{}{}^{}$Mg(125 MeV),4n], ${}_{}{}^{165}{}_{}{}^{}[_{}^{28}{}_{}{}^{}$Si(140 MeV),4n], and ${}_{}{}^{175}{}_{}{}^{}[_{}^{20}{}_{}{}^{}$Ne(128 MeV),6n] and its subsequent decay studied by in-beam γ-ray spectroscopy techniques. Among the firmly established features there are two band structures resulting from the coupling of the h(9/2 and i(13/2 proton intruder states to the oblate ground-state band of the Hg core. However, above a certain excitation energy both bands show structural changes possibly related to the prolate shaped excited band in ${}_{}{}^{188}{}_{}{}^{}\mathrm{Hg}$. At least for the π̃i(13/2 case, coexistence of both shapes is observed.