Photoelectric Work Function of a Copper Single Crystal for the (100), (110), (111), and (112) Faces

The electron work function was measured by the Fowler method for four faces of a copper single crystal. The crystal was cleaned by repeated cycles of ion bombardment and annealing at 700°C under ultrahigh vacuum conditions. With uncertainties of $\delta \Phi =\pm 0.03$ eV, the work functions were found to be ${\Phi }_{110}=4.48\mathrm{}$ eV, ${\Phi }_{112}=4.53\mathrm{}$ eV, ${\Phi }_{100}=4.59\mathrm{}$ eV, and ${\Phi }_{111}=4.94\mathrm{}$ eV.