Ab. Andrews et al., SURFACE CORE-LEVEL SHIFTS OF TA(110) AND W(110) VERSUS ALKALI-METAL-ATOM COVERAGE - IMPLICATIONS FOR THE ALKALI-METAL SUBSTRATE INTERACTION, Physical review. B, Condensed matter, 49(12), 1994, pp. 8396-8401
The change in the average surface-atom core-level shift (SCS) produced
by submonolayer coverages of alkali adsorbates is quite small for bot
h Ta(110) and W(110), less than 45 meV in magnitude. The small change
of the measured SCS's as a function of coverage decisively supports th
e covalent-bonding picture of alkali adsorption proposed by Ishida and
Terakura.