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Lecture Paul S. Bagus

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WanneerWaar
08 augustus 2006 FWN-Building 5114.0004, Nijenborgh 4, 9747 AG, Groningen
Speaker: Paul S. Bagus
Affiliation: Department of Chemistry, University of North Texas, Denton, TX, USA
Title: How and why adsorbates induce changes in the work functions of metal surfaces
Date: Tue Aug 8, 2006
Start: 11.00
Location: FWN-Building 5114.0004
Host: H.B. Braam
Telephone: +31 50 363 4374

Abstract

Adsorbates may induce large shifts in the work function, phi, of a metal surface. The traditional explanation of work function changes has been in terms of charge transfer, CT, between the substrate and the adsorbate with CT from the adsorbate to the substrate leading to a decrease in phi and to an increase in the interface dipole, as for alkali atom adsorbates. We show that other mechanisms besides CT make important, often dominant, contributions leading to the work function change, delta phi. We present a theoretical framework that provides a unified understanding for different types of adsorbate-substrate interactions ranging from van der Waals to strong chemical bonding. For pure van der Waals interactions, we consider adsorbed rare gasses; we also consider cases of weakly bonded organic molecules where covalent bonds may be present in addition to the van der Waals interaction. For strongly bonded adsorbates, we consider cases of both covalent and ionic bonding. The understanding that has been obtained identifies how the delta phi are related to the chemistry and physics of the adsorbate-substrate interaction. It is based on the analysis of ab initio wavefunctions that describe the interaction.
Laatst gewijzigd:22 oktober 2012 14:31