ELECTRODE POTENTIAL-INDUCED RECONSTRUCTION OF AU(100) - EFFECT OF CHEMISORPTION ON NANOSCALE DYNAMICS AS PROBED BY IN-SITU SCANNING-TUNNELING-MICROSCOPY

The effect of iodide chemisorption on the nanoscale real-space dynamic s associated with the electrode potential-induced formation and remova l of the hexagonal reconstruction on Au(100) in aqueous solution has b een examined by means of in-situ scanning tunneling microscopy under p otentiodynamic conditions. Unlike in ''nonadsorbing'' media such as pe rchloric acid where the (1 x 1) --> (hex) phase change is sloW (t1/2 a pproximately 10 min), requiring adatom diffusion from terrace edges, t he potential-induced transition in iodide can be remarkably rapid (<0. 2 s). The latter features facile large-scale (ca. 10-20 nm) gold mass transport emanating from former (1 x 1) terraces as well as from terra ce edges. The likely roles of chemisorption in inducing such remarkabl y rapid reconstruction are briefly discussed.