Neutron intermultiplet spectroscopy of UPd3 and UPt3

Neutron intermultiplet spectroscopy has been used to re-examine UPd(3) and UPt(3) at 17 K. In UPd(3), the (3)H(4) --> (3)F(2) transition is observed at 395 meV, confirming a localised 5f(2) state for the uranium ions. In the heavy fermion compound UPt(3), only a small trace of this transition remains, indicating that the 5f electrons in this material are of a predominantly itinerant nature. The Q dependence of the transition in UPd(3) has also been determined. The transition intensities are found to differ by a factor of similar to 2 from that predicted by calculations.