Na adsorption process on a ZrC(100) surface

The Na adsorption process on a ZrC(100) surface has been studied with core-level photoemission spectroscopy and Auger electron spectroscopy. Na coverage (θNa) dependences of the line shape and the binding energy of the Na 2p photoemission peak and of the Na LVV Auger spectrum suggest that Na adsorption proceeds via the following three steps: (i) the formation of the polarized adsorbed layer at θNa < ∼ 0.3 ML, (ii) the coexistence of the polarized adsorbates and the condensed metallic adsorbates at 0.3 < θNa < 0.7 ML, and (iii) almost all adsorbates form the metallic phase at θNa > 0.7 ML.