Field evaporation of gold in single- and double-electrode systems

Field evaporation of gold as positive and negative ions in single- and double-electrode systems is investigated with the charge-exchange model using atomic potentials from an embedded-atom method and a method discussed by H. Gollisch [Surf. Sci. 166, 87 (1986); 175, 249 (1986)]. For the single-electrode geometry of the field-ion microscope, ${\mathrm{Au}}^{+}$ should be the observable ion species. In the double-electrode geometry of the scanning tunneling microscope, ${\mathrm{Au}}^{2\mathrm{-}}$ should be the favored ion species since it requires the lowest evaporation field.