The adsorption of immobilely deposited and thermally equilibrated Cs layers has been studied on the (110), (211), (100), (111), (103), and (115) regions of a tungsten field emitter. The workhyphen;functionhyphen;vshyphen;coverage data permit resolution into adsorbate charge and effective dipole length, at least on the high workhyphen;function planes. The results indicate ionic adsorption on (110) and probably (211) at low coverage, with charge diminishing on all planes asthgr;increases. Dipole lengths exceed the ionic radius of Cs by 1.4ndash;2 Aring;, indicating the effect of finite screening at the metal surface. The adsorption energies and their change withthgr;can be interpreted in terms of the ldquo;metalletrdquo; model.
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