Na and Cs intercalation of 2H-TaSe2 studied by photoemission

The electronic structure of the layered compound 2H-TaSe2 has been studied using angle-resolved photoemission before and after in situ intercalation w ith Na and Cs. Core level spectra verified that Na and Cs both intercalate easily at room temperature, with only small amounts remaining on the surfac e. Valence band spectra revealed changes in the electronic band structure w hich were much more extensive than predicted by the rigid band model, but w hich were in reasonable agreement with theoretical bands calculated by the LAPW method. Some discrepancies between the experimental and calculated res ults are probably due to intercalation induced changes in the stacking of h ost layers. A general similarity with results from transition metal dichalc ogenides with 1T structure indicates that the intercalation properties are not critically dependent on the internal structure of the host layers.