Excitation of low-lying state by E3 transition in reaction with real photons

The yield of the isomeric state 117mSn (Eiso = 314.58 keV) has been measured in (gamma, gamma') reaction by activation method with the bremsstrahlung end-point energy from 2.1 to 3.0 MeV. Only one intermediate state (IS) responsible for the isomer feeding has been found. The excitation energy of the IS (2.25 +/- 0.05) MeV and photoproduction integral cross section (0.022 +/- 0.002) eV b have been deduced. Microscopic calculations within the Quasiparticle-phonon model have been performed to learn on the IS structure. We conclude that the IS is excited in the present experiment by the E3-transition.