3,513 research outputs found
Concept for improved vacuum pressure measuring device
To measure vacuum pressures in the range of 5 times 10 to the minus 7 to 5 times 10 to the minus 16, a semiconductor resistor composed of sintered zinc oxide is used. Through the effect of surface absorbed gases on the resistance of the semiconductor material, very low pressures are measured
Collective surface diffusion near a first-order phase transition
For a large class of lattice models we study the thermodynamic factor,
, of the collective surface diffusion coefficient near a first-order
phase transition between two phases at low temperatures. In a two-phase regime
its dependence on the coverage, \te, is \Phi \approx \te/[(\te-\te_-)(\te_+
- \te)N], where is the number of adsorption sites and \te_\pm are the
single-phase coverages at the transition. In the crossover between the
two-phase and single-phase regimes \Phi(\te) is shown to have a more complex
behavior. The results are applied to a simple 2D lattice model.Comment: 9 pages, 4 figure
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