Three-dimensional atomic images of a Pt(111) surface are obtained by direct inversion of multiple low-energy Kikuchi electron-diffraction patterns. The images are in the backscattering direction. and the positions of the images are consistent with those expected from the atomic structure near the Pt(111) surface. The strong electron scattering of the Pt atoms causes no observable problems in the Kikuchi electron holography.

The work function of atomically uniform Ag films grown on Fe(100) is measured as a function of film thickness. It shows layer-resolved variations as a result of quantum confinement of the valence electrons. A first-principles calculation reproduces the observed variations except for very thin films (one and two monolayers), and the differences can be attributed, in part, to strain effects caused by the lattice mismatch between Ag and Fe. These results illustrate the close interaction between interface effects and surface properties.

The work function of atomically uniform Ag films grown on Fe(100) is measured as a function of film thickness. It shows layer-resolved variations as a result of quantum confinement of the valence electrons. A first-principles calculation reproduces the observed variations except for very thin films (one and two monolayers), and the differences can be attributed, in part, to strain effects caused by the lattice mismatch between Ag and Fe. These results illustrate the close interaction between interface effects and surface properties.

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We have carried out first-principles calculations of Pb (111) films up to 25 monolayers to study the oscillatory quantum size effects exhibited in the surface energy and work function. These oscillations are correlated with the thickness dependence of the energies of confined electrons, which can be properly modeled by an energy-dependent phase shift of the electronic wave function upon reflection at the interface. It is found that a quantitative description of these quantum size effects requires a full consideration of the crystal band structure.

We have carried out first-principles calculations of Pb (111) films up to 25 monolayers to study the oscillatory quantum size effects exhibited in the surface energy and work function. These oscillations are correlated with the thickness dependence of the energies of confined electrons, which can be properly modeled by an energy-dependent phase shift of the electronic wave function upon reflection at the interface. It is found that a quantitative description of these quantum size effects requires a full consideration of the crystal band structure.

Coherent two-field spectroscopy calculations with different choices of the quantization (z) axis are compared. In a system driven by a strong coupling field and a weak probe field, alignment of the z axis along either the polarization direction of a linearly polarized coupling field or the propagation direction of a circularly polarized coupling field is shown to simplify the calculations and facilitate interpretation of the results. The advantages of a suitable choice of the z axis are highlighted with an example of a degenerate three-level system of electromagnetically induced transparency. (C) 2002 Optical Society of America.

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