Structure and registry of the silica bilayer film on Ru(0001) as viewed by LEED and DFT

Abstract

Silica bilayers are stable on various metal substrates, including Ru(0001) that is used for the present study. In a systematic attempt to elucidate the detailed structure of the silica bilayer...

Models for Reactions in Confined Space: Can Surface Science Contribute? A Review and Perspective

“…This is another indication, that the assumption to be dealing with static structure is probably not appropriate. This becomes evident when we look at the results of the LEED I/V studies [39]. Note, that the quality of agreement between calculation of the diffraction intensities as a function of electron energy and the experimental observations is measured by the so-called Pendry-R-factor, varying between 1 (no correlation) and 0 (complete agreement).…”

“…The question arising at this point is: Are there any direct experimental indications that the position of the bilayer depends on the oxygen coverage at the surface? Since those data had been missing so far, the question triggered a LEED I/V to explicitly determine the structure of the bilayer system [39]. Parallel to the measurements and its evaluation, calculations on the metal supported silica bilayer have been performed, in order to evaluate the energy differences between structures, where the silica film has been moved parallel to the metal surface, depending on the oxygen coverage on the Ru(0001) surface.…”

“…Parallel to the measurements and its evaluation, calculations on the metal supported silica bilayer have been performed, in order to evaluate the energy differences between structures, where the silica film has been moved parallel to the metal surface, depending on the oxygen coverage on the Ru(0001) surface. As demonstrated in [39] there are directions across the surface of a 3ORu(0001) surface, where the activation energy to shift the film parallel to the surface is only of the order of 0.5 eV. This is another indication, that the assumption to be dealing with static structure is probably not appropriate.…”

“…It should be clear that this is not a unique solution but a possible one. The pros and cons are discussed in [39], see also Refs. [40,41].…”

“…15 Schematic representation of those structures contributing to the best LEED I/V simulation with a Pendry R-factor of 0.16. The models have been reproduced with permission from [39] film cannot be described by a single fixed structure, but rather only by a superposition of several structures. Only by considering a superposition are we able to obtain a reasonable Pendry R-factor.…”