title: Spectromicroscopy of pulses transporting alkali metal in a surface reaction.
abstract: The NO + H2 reaction on a potassium promoted Rh(110) surface is shown to sustain the formation of spatio-temporal periodic patterns leading to mass transport phenomena. The excitation of pulses and the mass transport mechanism are studied in the 10(-7) and 10(-6) mbar pressure range, with the potassium coverage varying between θK = 0.05 and θK = 0.12 ML. Using spectroscopic photoemission and spectroscopic low energy electron microscopy (SPELEEM) as well as related microprobe diffraction techniques, we show that the excitation mechanism comprises a cyclic structural transformation: K + O-coadsorbate → (2 × 1)-N → c(2 × 4)-2O,N → K + O coadsorbate. Laterally resolved spectroscopy demonstrates that potassium is accumulated in front of the nitrogen pulses, suggesting that adsorbed nitrogen acts as a diffusion barrier for potassium.
authors: TU München, Chemie Department, Lichtenbergstr. 4, D-85748 Garching, Germany.
authors: S
authors: S
authors: Günther
authors: Hong
authors: H
authors: Liu
authors: T O
authors: TO
authors: Menteş
authors: A
authors: A
authors: Locatelli
authors: R
authors: R
authors: Imbihl