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Spectromicroscopy of pulses transporting alkali metal in a surface reaction.

Authors
Type
Published Article
Journal
Physical Chemistry Chemical Physics
1463-9084
Publisher
The Royal Society of Chemistry
Publication Date
Volume
15
Issue
22
Pages
8752–8764
Identifiers
DOI: 10.1039/c3cp44478c
PMID: 23632422
Source
Medline
License
Unknown

Abstract

The NO + H2 reaction on a potassium promoted Rh(110) surface is shown to sustain the formation of spatio-temporal periodic patterns leading to mass transport phenomena. The excitation of pulses and the mass transport mechanism are studied in the 10(-7) and 10(-6) mbar pressure range, with the potassium coverage varying between θK = 0.05 and θK = 0.12 ML. Using spectroscopic photoemission and spectroscopic low energy electron microscopy (SPELEEM) as well as related microprobe diffraction techniques, we show that the excitation mechanism comprises a cyclic structural transformation: K + O-coadsorbate → (2 × 1)-N → c(2 × 4)-2O,N → K + O coadsorbate. Laterally resolved spectroscopy demonstrates that potassium is accumulated in front of the nitrogen pulses, suggesting that adsorbed nitrogen acts as a diffusion barrier for potassium.

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