In situ imaging of structural changes in a chemical wave with low-energy electron microscopy: the system Rh(110)/NO+H2

Low-energy electron microscopy (LEEM) and micro-LEED (micro low-energy electron diffraction, beam diameter 1 μm) have been employed to resolve the structural changes which occur during chemical wave propagation in the system Rh(110)/NO+H2. In a pulse the surface undergoes cyclic structural transformations in the sequence c(2×6)-O, (3×1)-N, (2×1)-N, c(2×4)-2O,N, c(2×6)-O. In situ dark field imaging with superstructure beams was used to demonstrate the contribution of the various reconstruction phases to pulse propagation. Based on the LEED/LEEM results, an excitation mechanism is proposed.