Adsorption of K on NbC(100): photoemission and thermal desorption study

Abstract

The adsorption state of K on NbC(100) has been studied with core-level photoemission spectroscopy (CLPES) and thermal desorption spectroscopy (TDS). The adsorption mechanism of K on the NbC(100) surface is found to be very unique as compared with those of many alkali-metal surface systems. The TDS study shows that the desorption energy of K increases with the increase of K coverage ( θ K). The work function measurements show that the polarization of the NbC(100) surface after K adsorption is small as compared with those for many alkali-metal surface systems. The lineshape analysis of the K 3p photoemission spectra shows that the valence electronic density of states for adsorbed K is nearly independent on the coverage. Considering these results, it is proposed that the K-adsorbed layer is grown via the island formation mechanism.