Effects of a potassium adlayer on the interaction of nitrogen with the Rh(111) surface

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Abstract

The adsorption of N2 and atomic nitrogen generated in a high-frequency discharge tube (N + N2) has been studied on clean and K-covered Rh(111) surfaces with TDS, AES, and work-function meaurements at 100-600 K. Dinitrogen adsorbed on a clean Rh at 100 K desorbs with Tp=155-160 K. No adsorption and dissociation of N2 was experienced at 300-600 K under UHV condition. Preadsorbed K suppresses the uptake of N2 at 100 K. TDS and AES experiments did not show the formation of any new nitrogen adsorption state. A very limited dissociation of N2, induced by potassium adlayer, was observed only at 500 K and at high N2 pressure. The atomic nitrogen bonds strongly to the Rh(111) surface and desorbs associatively in two stages at Tp=561-712 K and Tp=453 K. The preadsorbed K influenced only little the rate and extent of the uptake of nitrogen atom and slightly lowered the peak temperatures for the associative desorption of nitrogen in the main state. At the same time, potassium adatoms induced the formation of a new, high-temperature state with Tp=720-800 K. A significant stabilization of potassium (around monolayer) was found in the coadsorbed layer. A fraction of potassium desorbed together with the more stable nitrogen. This feature indicates a direct interaction and a mutual stabilization between adsorbed K and N.

Original languageEnglish
Pages (from-to)55-66
Number of pages12
JournalSurface Science
Volume258
Issue number1-3
DOIs
Publication statusPublished - Nov 2 1991

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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