1 step theory of photoemission from Schottky surface states W. Wan, T-C Chiang and H. A. Padmore Metallic photocathodes are normally made of disordered highly polycrystalline materials, whose main characteristics, such as quantum efficiency (QE) and emittance, can be modeled rather well by the 3-step model [1, 2, 3]. Yet it fails to explain the dependence of the QE on the incident angle and the photon energy of the p-polarized light from the ordered crystalline surface that supports a surface state. In order to explain the experimental data, a one-step theory of photoemission from the (111) surface of a noble metal was developed. It is the 3D extension of a 1D theory [4] which was constructed using the nearly- free-electron two-band model and the time-reversed LEED formulism. Details of the theory will be shown as well as comparison with data. In addition to good agreement with the QE data, the theory predicts that the emittance of the photoelectrons from the surface is smaller than that from the polycrystalline surface.

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