Systematics of magnetic dipole strength in the stable even-mass Mo isotopes

The nuclides 92Mo, 98Mo and 100Mo have been studied in photon-scattering experiments by using bremsstrahlung. Dipole and quadrupole excitations in 92Mo were investigated in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator of the Forschungszentrum Rossendorf. Photon-scattering experiments on 98Mo and 100Mo were carried out at the Dynamitron accelerator of the Stuttgart University at electron energies from 3.2 to 3.8 MeV. Six dipole transitions in 98Mo and 19 in 100Mo were observed for the first time in the energy range from 2 to 4 MeV. Systematics of the magnetic dipole strength in the isotopic chain of the even-mass isotopes from 92Mo to 100Mo are discussed. The experimental results are compared with predictions of the shell model and with predictions of the quasiparticle-random-phase approximation in a deformed basis. The latter show significant contributions of isovector-orbital and isovector-spin vibrations.