Photoexcitation of the isomers of 19 nuclides was examined in this work. Four accelerators were used as sources of bremsstrahlung to expose the samples and end-point energies covered the range from 0.5 to 11 MeV. No evidence was found for nonresonant processes of excitation. However, more than half the cases showed enhanced channels for the resonant photoexcitation of isomers with integrated cross sections approaching ${10}^{\mathrm{-}21}$ ${\mathrm{cm}}^2$ keV. These results are three to four orders of magnitude larger than values usually characterizing (γ,γ’) reactions.

• Received 21 April 1989

DOI:https://doi.org/10.1103/PhysRevC.43.1238