Search

Your search keyword '"Wandelt, K."' showing total 959 results
Start Over Author "Wandelt, K."
959 results on '"Wandelt, K."'

222. Studies of the Facetting of the Polished (100) Face of CaF2.

Author

Dahbringhaus, H., Schick, M., Wandelt, K., Deuster, V., Kayser, T. H., and Klapper, H.

Subjects
ELECTRON microscopy, ATOMIC force microscopy, SPECTRUM analysis, ELECTRON diffraction, CHEMICAL elements spectra
Abstract

The present paper deals with studies of the facetting of the polished (100) surface of CaF2 during annealing and growth in UHV using low energy electron diffraction (LEED), atomic force microscopy (AFM), and transmission electron microscopy (TEM). First morphological modifications of the polished surfaces become visible at temperatures of T = 874 K. Surfaces annealed at T = 974 K exhibit a micro-roughening with pyramidal protrusions and corresponding depressions. LEED studies indicate the evolution of {111} facets. Reflexes from the (100) surface are not seen. After growth of about 660 monolayers of CaF2 at T = 1093 K and a saturation ratio S = 33 from the vapor phase, larger pyramid-like or hip roof-like crystallites are developed. The results of AFM height profiles as well as of the LEED investigations indicate again the formation of {111} facets as proved by their angles of 54.7° with the base (100) surface. This shows that the crystallites are homoepitaxially grown on the underlying CaF2 substrate. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2003
Full Text
View/download PDF

232. Electronic structure of the Ru(0001) surface

Author

Pelzer, T, primary, Ceballos, G, additional, Zbikowski, F, additional, Willerding, B, additional, Wandelt, K, additional, Thomann, U, additional, Reuß, Ch, additional, Fauster, Th, additional, and Braun, J, additional

Published
2000
Full Text
View/download PDF

233. Surface potential around potassium promoter atoms on Rh(111) measured with photoemission of adsorbed Xe, Kr, and Ar

Author

Janssens, T.V.W., Castro, G.R., Wandelt, K., Niemantsverdriet, J.W., Janssens, T.V.W., Castro, G.R., Wandelt, K., and Niemantsverdriet, J.W.

Abstract

The effect of K promoter atoms on Rh (111) on the surface potential was studied with photoemission of adsorbed Xe, Kr, and Ar. By using probe atoms of different sizes, the authors have measured the variation of the surface potential in the vicinity of a K atom. The surface potentials were probed on Rh (111) surfaces, covered with 2.7, 4.1, and 5.0 at. % K. At all these coverages, the authors find a decrease in potential close to the K atoms (4 .ANG.) on the order of 1-2 eV, which depends on the lateral distance from the K atom. Further away from the K atoms, the authors find a nearly const. potential that is 0.4-1.0 V lower than on unpromoted Rh (111). This implies that all available absorption sites on the promoted surface are affected by the presence of K. The measured potentials depend on the K coverage, indicating that the potentials result from a cumulative effect of all K atoms on the surface. The obsd. changes in surface potential agree well with the potential in a hexagonal network of dipoles, indicating that they are of electrostatic origin and do not require long-range changes in electronic structure. [on SciFinder (R)]

Published
1994

245. Long and short range effect of alkali promoters on metal surfaces : K on Rh(111)

Author

Janssens, T.V.W., Wandelt, K., Niemantsverdriet, J.W., Janssens, T.V.W., Wandelt, K., and Niemantsverdriet, J.W.

Abstract

Photoemission of physisorbed noble gases was used to study the variation of the surface potential on a K-promoted Rh (111) surface. The predominant effect of K is to lower the potential on nearest neighbor sites by 1-1.5 eV, but indicate also that the potential on next nearest neighbor sites is still 0.4-1 eV lower than on unpromoted Rh, depending on the K coverage. The latter values qual. agree with the cumulative effect of K/Rh dipoles which form an ordered array on the surface. [on SciFinder (R)]

Published
1993

Catalog

Books, media, physical & digital resources
See catalog results