OPTICAL-TRANSITIONS IN CESN3 AND LASN3

Interband optical transitions in CeSn3 and LaSn3 have been investigated by measuring and calculating from band theory the optical conductivities of both compounds. For both compounds, interband transitions start at low energies (0.3 eV for CeSn3 and 0.5 eV for LaSn3) and these structures are mostly due to d --> f and f --> d transitions between band-like d and f states originating from Ce or La atoms The structures at higher energies (greater than 1 eV) strongly involve f --> d and d --> p transitions with p states originating from Sn atoms Good qualitative agreement between calculation and experiment has been achieved for these higher-energy structures for both compounds. The larger strength of the structures in CeSn3 above 1 eV is mainly due to the existence of more occupied band-like f states in CeSn3 than in LaSn3.