Energy Distribution in Field Emission from Adsorbate-Covered Surfaces

A calculation of the total energy distribution of field-emitted electrons in the presence of chemisorbed atoms shows that j () -{j₀ () }{j₀ () }=u () ^2 ImG₀₀ () if the adsorbate resonance level lies within the conduction band of the metal. j () and j₀ () are the current densities per unit energy in the presence and absence of the adsorbate, respectively; the energy is measured from the vacuum level; x₀ is the surface-adsorbate distance; and (1 ImG₀₀ is the local density of states at the adsorbate. u () ^22{ (-2m{{^2}) }^1{2}x₀+43 (2m{{^2}) }^1{2} (-) ^3{2} (eF) ^-1 (v (y) -1) }, where F is the electric field and v (y) is the image-potential correction factor. The expression given above for the tunneling current is general and independent of the explicit form of G₀₀. if the adsorbate resonance lies below the bottom of the conduction band, then j () -{j₀ () }{j₀ () }<0, in agreement with the results of Duke and Alferieff.