[en] We consider a simple model of the work function based on the overlapping spherical atomic charge-density approximation to the potential (the so-called Mattheiss construct). We show analytically that the dipole barrier of nonpolar crystals is simply related to a moment of the spherical densities, and hence there is no face dependence of the work function in this model. For the polar faces of polar crystals there is an additional face-dependent term that was found previously by different means. We calculate the bulk contributions to the work function for the metals with atomic number less than 50. The dipole barriers obtained from free-atomic densities result in work functions which are on the average approx.80% too large. The use of contracted atomic densities, while leaving the bulk density virtually unchanged, decreases the dipole barriers and yields work functions in reasonable agreement with experiment. Some implications for surface calculations, electronegativity scales, and charge-transfer and bonding trends are briefly discussed

No abstract available

No abstract available

[en] The main idea of the adsorbed xenon photoemission method for studying local work functions var-phi _loc of an electron on a heterogeneous surface is based on the relation triangle E^F_b = -triangle var-phi _loc, where triangle E^F_b is the difference between the binding energies of the Xe5p_1/2 level relative to the Fermi level of the adsorbed Xe atom of different regions of a heterogeneous surface, and triangle var-phi _loc is the difference between the local work functions at these regions

[en] It has recently been observed that adsorbed Au and Hg do not quench the W(100) surface resonance up to monolayer coverage. We report here that Cu does quench the W(100) surface resonance at theta > = 0.5 monolayers. This suggests that the effective potential of Cu differs more strongly from that of W than do the effective potentials of Au or Hg. (orig.)

[en] Calculations of positron and positronium atom work functions in transition metals are described with an analysis of the surface and internal contributions. Negative work functions are obtained for elements towards the centre of the transition series, in qualitative agreement with experimental observations. (author)

[en] The goal of this investigation was to extend the ability to perform isotopic analysis of plutonium to samples as small as possible. Plutonium ionizes thermally with quite good efficiency (first ionization potential 5.7 eV). Sub-nanogram sized samples can be analyzed on a near-routine basis given the necessary instrumentation. Efforts in this laboratory have been directed at rhenium-carbon systems; solutions of carbon in rhenium provide surfaces with work functions higher than pure rhenium (5.8 vs. ∼ 5.4 eV). Using a single resin bead as a sample loading medium both concentrates the sample nearly to a point and, due to its interaction with rhenium, produces the desired composite surface. Earlier work in this area showed that a layer of rhenium powder slurried in solution containing carbon substantially enhanced precision of isotopic measurements for uranium. Isotopic fractionation was virtually eliminated, and ionization efficiencies 2-5 times better than previously measured were attained for both Pu and U (1.7 and 0.5%, respectively). The other side of this coin should be the ability to analyze smaller samples, which is the subject of this report

[en] For a superconductor in a stationary condition, it can be shown that a gradient in the chemical potential is balanced by a gradient in the internal electrostatic potential. An attempt has been made to measure these electrostatic effects directly for niobium by measuring the temperature derivative of the contact potential as a function of temperature. (1 figure)

[en] Starting from a definition of the work function in terms of total energies of the electron system it is shown that this work function can be obtained from the single-particle Schroedinger equations in the density-functional formalism in the way suggested by the Sommerfeld model. It is also shown that the change of the equilibrium ion positions accompanying the ionization of the crystal has no influence on the work function. A comparison is made with Koopmanns' theorem. The use of several potentials for computations of the work function is critically investigated. (orig.)

[en] Short communication