Field emission energy distribution from adsorbate covered tungsten

We discuss the effect of various classes of adsorbates on the surface states and resonances known to produce structure in the field emission energy distribution from (100) tungsten. We show that it is the overlayer geometry which is of importance in determining whether or not the resonances and concomittant FEED structure persist in the presence of adsorbates. In particular, a c(2 × 2) krypton overlayer destroys the structure while a (1 × 1) gold overlayer does not.