Dipole strength distributions in stable odd-mass nuclei in the vicinity of the N=82 isotones

The low-lying dipole strength distributions in the odd-mass nuclei $^{135}$Ba, $^{137}$Ba, $^{139}$La and $^{141}$Pr were studied in nuclear resonance fluorescence (NRF) experiments performed at the Stuttgart Dynamitron facility. experiments used bremsstrahlung beams with endpoint energies of 4.1~MeV. The spin selective NRF reaction allowed the excitation of states through dipole transitions, up to 4~MeV. A special focus is the fragmented E1-strength of transitions connecting the ground state to states of the $[2^+ \otimes 3^-] \otimes particle/hole$ coupling. The summed strength of the odd-mass nuclei is compared with the E1-strength of the $[2^+ \otimes 3^-]_{1^{-}}$ two-phonon states of the neighboring even-even core nuclei.