TRANSMISSION LOW-ENERGY-ELECTRON DIFFRACTION (TLEED) AND ITS APPLICATION TO THE LOW-VOLTAGE POINT-PROJECTION MICROSCOPE

Solutions to the mixed Bragg-Laue case for transmission low-energy electron diffraction (TLEED) are derived for thin crystalline slabs and applied to the low-voltage (0-1 kV) field-emission point-projection transmission microscope [Fink, Schmid, Kreuzer & Wierbicki (1991). Phys. Rev. Lett. 67, 1543-1546). Absorption due to inelastic scattering, exchange and virtual inelastic scattering effects are considered. The relationship between Fourier imaging, shadow imaging, holography of extended objects and holography of small objects is briefly discussed, together with the optimum energy for atomic-resolution electron microscopy and holography. The importance of multiple scattering in transmission-electron interference patterns obtained at LEED energies with spherical-wave illumination is evaluated and the nature of the optical potential that might be recovered holographically is discussed.