Energy distribution of field emission electrons from a niobium 〈111〉 tip

Abstract We have fabricated Nb〈111〉 tips by electrochemical polishing from the single crystal wires along the 〈111〉 orientation, which has been prepared by means of floating zone, spark erosion, and mechanical polishing techniques. The energy distribution of the field emission electrons from the Nb〈111〉 tip has been measured at room temperature using a high resolution electron spectrometer recently developed. The experiments were carried out in vacuum of ∼ 3 × 10 −9 Pa, and the tip surface was cleaned by field evaporation. The main part of the energy distribution is in agreement with the theoretical curves calculated on the basis of the Fowler-Nordheim theory. Two discrepancies are observed on low and high energy sides.