OXYGEN-INDUCED SURFACE CORE-LEVEL SHIFTS OF W(110) DEDUCED FROM SURFACE SEGREGATION ENERGIES

We calculate the core-level shift induced by oxygen adsorbates on the surface atoms of W(110). We use the equivalent core approximation whic h reduces this problem to the computation of the variation of the surf ace segregation energy of a rhenium impurity in a (110) tungsten cryst al due to the presence of chemisorbed oxygen atoms. The calculation is carried out in the framework of the tight-binding approximation. The results are compared with previous simpler approaches and suggest a ne w interpretation of experimental data.