Scattering patterns and energy distribution of scattered electrons under field emission conditions of scanning tunneling microscopy

A low-energy electron diffraction (LEED) apparatus using field emissions from scanning tunneling microscope (STM) tips has been developed. The apparatus was designed to detect scattered electrons toward the surface normal direction using the tip shield and the extractor. The kinetic energies of the scattered electrons were measured. There were two bright regions. One consisted of inelastically scattered electrons, while the other mainly consisted of elastically scattered electrons. The behavior of the latter region was consistent with our simple calculations. This result supports the possibility that the LEED uses field emissions from STM tips. The specific diffraction patterns of surface structures have not yet been obtained. The features of the apparatus are discussed.