DIRECT OBSERVATION OF EXCHANGE SPLITTINGS IN RARE EARTH DIMERS BY INELASTIC NEUTRON SCATTERING A. Dönni, A. Furrer, H. Blank, A. Heidemann and H. U. Güdel J. Phys. Colloques, 49 C8 (1988) C8-1513-C8-1514 DOI: 10.1051/jphyscol:19888697