Alkali-induced effects on metal substrates and coadsorbed molecules |
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Authors: | TS Rahman S Stolbov F Mehmood |
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Institution: | (1) Department of Physics, University of Central Florida, Orlando, FL 32816, USA;(2) Department of Chemical Engineering, University of Wisconsin, Madison, WI 53706-1691, USA |
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Abstract: | We present results of ab initio electronic structure calculations based on density functional theory which show in detail
several effects of alkali adsorption on metal substrates and on molecules coadsorbed on the substrate. First, calculations
of the isoelectronic reactivity index demonstrate a dramatic enhancement of the electronic polarizability of the metal substrate
extending it several angstroms into the vacuum. This phenomenon is traceable to an unusual feature induced in the surface
potential on alkali adsorption. The effect appears to be general and helps explain the observed substantial decrease in the
vibrational frequency of molecules such as CO and O2 when co-adsorbed with alkalis on metal surfaces. Next, for the oxidation of CO on Pd(111), we illustrate the changes in the
reaction pathway and activation energy barriers induced in the presence of coadsorbed K.
PACS 73.20.-r; 71.15.-m |
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