ADSORPTION OF K ON NBC(100) - PHOTOEMISSION AND THERMAL-DESORPTION STUDY

The adsorption state of K on NbC(100) has been studied with core-level photoemission spectroscopy (CLPES) and thermal desorption spectroscop y (TDS). The adsorption mechanism of K on the NbC(100) surface is foun d to be very unique as compared with those of many alkali-metal surfac e systems. The TDS study shows that the desorption energy of K increas es with the increase of K coverage (theta(K)). The work function measu rements show that the polarization of the NbC(100) surface after K ads orption is small as compared with those for many alkali-metal surface systems. The lineshape analysis of the K 3p photoemission spectra show s that the valence electronic density of states for adsorbed K is near ly independent on the coverage. Considering these results, it is propo sed that the K-adsorbed layer is grown via the island formation mechan ism.