Effect of the emitter temperature and emitter atom ionization potential on field evaporation

The field evaporation of nickel, nichrome alloy, and tungsten carbide at different temperatures is studied with a time-of-flight atomic probe and a field emission microscope. The charge of evaporating ions does not depend on the emitter temperature: it decreases with decreasing evaporating field F _ev. If F _ev does not vary with temperature, so does the charge of the ions. In the case of multicomponent emitters with different ionization potentials of the components, the components evaporate at the same values of F _ev in the form of atoms and ionized clusters. The reason for such behavior is that the initial evaporation of the easily ionizable component decreases the binding energy of harder-to-ionize ones to the point where they can evaporate at the same field.