Elucidating complex surface reconstructions with atomic-resolution scanning tunneling microscopy: Au(100)-aqueous electrochemical interface.

Abstract

The utilization of scanning tunneling microscopy (STM) with high-quality atomic resolution for elucidating complex electrochemical surface reconstructions is illustrated for the Au(100)-aqueous interface. The reconstruction, triggered by negative surface electronic charges, exhibits typically a (5\ifmmode\times\else\texttimes\fi{}27) symmetry involving quasihexagonal surface packing. The detailed atomic arrangements within the unit cell, including the spatial relationship of the reconstructed top layer to the underlying substrate, can be deduced from STM images featuring adjoining (5\ifmmode\times\else\texttimes\fi{}27) and (1\ifmmode\times\else\texttimes\fi{}1) domains. A number of subtly different superstructures could also be discerned; these are seen to arise from the need for the observed ribbonlike reconstructed domains to circumnavigate surface defects. The unique virtues of atomic-resolution STM for obtaining detailed local information on surface atomic arrangements in complex nonuniform systems are pointed out, along with its applicability (on an equal footing) to electrochemical as well as vacuum surface science.