Elemental analysis of mixed lanthanide crystals using proton-induced K X-ray emission

A 3.2 MeV external proton beam K X-ray PIXE (particle-induced X-ray emission) facility has been constructed with the special aim of performing accurate and multi-elemental analysis of aqueous crystals containing mixtures of lanthanide compounds. Minimum detection limits and the problems of photon backscattering within the sample matrix are discussed in detail. The accuracy of the method was validated via comparison to commercial instrumental neutron activation analysis and to a new high performance liquid chromatography method; both of which were performed at independent laboratories. The values for the ratio {La}/{( La + Ce) }, in a series of mixed crystals, were applied to a low temperature investigation of crystal field splittings.