Intermultiplet transitions using neutron spectroscopy. Ch. 93

A new technique is described for probing the lanthanide 4f levels within metallic solids using high-energy neutrons from spallation sources to study transitions between different 2S+1LJ multiplets. Intermultiplet spectroscopy is useful in studying intermediate valence and heavy-fermion materials because it can be used to study the mixing of the two valence configurations in the former and to obtain information on the degree of hybridization of the 4f level in the latter. In studying mixed valent materials, the transition studied only involves the reorientation of the orbital and spin momenta of the 4f wave functions, rather than the removal of an electron from its shell as in optical studies, i.e. photoemission and X-ray-absorption, and thus there are no problems of final state screening effects. (author). 90 refs.; 8 figs.; 27 tabs