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\ifmmode^\circ\else\textdegree\fi{}C under ultrahigh vacuum conditions. With uncertainties of $\ensuremath{\delta}\ensuremath{\Phi}=\ifmmode\pm\else\textpm\fi{}0.03$ eV, the work functions were found to be ${\ensuremath{\Phi}}_{110}=4.48$ eV, ${\ensuremath{\Phi}}_{112}=4.53$ eV, ${\ensuremath{\Phi}}_{100}=4.59$ eV, and ${\ensuremath{\Phi}}_{111}=4.94$ eV.