Characterizing the atomic mass surface beyond the proton drip line via α-decay measurements of the πs 1/2 ground state of 165 Re and the πh 11/2 isomer in 161 Ta The α-decay chains originating from the πs 1/2 and πh 11/2 states in 173 Au have been investigated following fusion-evaporation reactions. Four generations of α radioactivities have been correlated with 173 Au m leading to a measurement of the α decay of 161 Ta m . It has been found that the known α decay of 161 Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt γ rays feeding the ground state of 173 Au. This prompt γ radiation was used to aid the study of the α-decay chain originating from the πs 1/2 state in 173 Au. Three generations of α decays have been correlated with this state leading to the observation of a previously unreported activity which is assigned as the decay of 165 Re g . This work also reports the excitation energy of an α-decaying isomer in 161 Ta and the Qα-value of the decay of 161 Ta g .