Two-Dimensional Silica Bilayers on Ru(0001): Structure and Substrate Registry

Early studies on the growth and structure of silica bilayers introduced a new two-dimensional material to the toolbox. Building on those studies, substrate supported silica bilayers were recently used as a model system for confined space reactions.[1] The observed reactions were best explained by assuming lateral and vertical movement of the bilayer relative to the substrate due to changes in the interfacial oxygen concentration during the reaction. Motivated by these observations, we sought to experimentally determine the structure of the silica bilayer, and, in particular, the distance between the film and the substrate, as well as its registry with respect to the substrate. Here present a low energy electron diffraction (I/V-LEED) study, supported by a detailed set of density functional theory (DFT) calculations. We conclude that a high-quality structure determination is only possible if several structural motives are taken into account by superimposing bilayer structures with varying registry to the oxygen covered substrate.

[1] Prieto et al., Ang Chem Int, 57 (2018) 8749