Low-energy electromagnetic excitation strengths in ${}^{121}\mathrm{Sb}$ and ${}^{123}\mathrm{Sb}$

Results are presented from nuclear resonance fluorescence experiments on the odd-mass nuclei ${}^{121}\mathrm{Sb}$ and ${}^{123}\mathrm{Sb}$ with $Z=51.\mathrm{}$ The improved sensitivity reached with the present NRF facility, installed at the 4.3 MV Dynamitron accelerator of the Stuttgart University, allowed the detection of huge numbers of weak photoexcitations in the stable Sb nuclei ${}^{121}\mathrm{Sb}$ (164 transitions) and ${}^{123}\mathrm{Sb}$ (83 transitions) in the energy range up to 4 MeV and 3.5 MeV, respectively. The data are compared to former results for odd-mass nuclei near the $Z=50\mathrm{}$ and $N=82\mathrm{}$ shell closures ${(}^{117}\mathrm{Sn},$ ${}^{139}\mathrm{La},$ ${}^{141}\mathrm{Pr},$ and ${}^{143}\mathrm{Nd}).\mathrm{}$ In the odd-mass nuclei within the $Z=50\mathrm{}$ region, a similar total amount of electromagnetic excitation strength below 4 MeV is found; however, in ${}^{121}\mathrm{Sb}$ and ${}^{123}\mathrm{Sb}\hspace{0.5em}\mathrm{}(Z=51\mathrm{})\mathrm{}$ this strength is much more fragmented than in ${}^{117}\mathrm{Sn}$ with a closed proton shell $\mathrm{}(Z=50\mathrm{}).$