THE DRIVING-FORCE FOR (PX-ROOT-3)[--](1X1) PHASE-TRANSITION OF AU(111) IN THE PRESENCE OF ORGANIC ADSORPTION - A COMBINED CHRONOCOULOMETRICAND SURFACE X-RAY-SCATTERING STUDY

In situ X-ray scattering and chronocoulometric experiments were perfor med to assess the influence of adsorption of pyridine, 2,2'-bipyridine and uracil on the driving force for the (p x root 3)-->(1 x 1) transi tion of the Au(111) surface. We have shown that the overall driving fo rce is a combination of the driving force due to charge and the drivin g force due to the adsorbate. We have estimated the magnitude of the t wo driving forces and have given the upper and lower limits to this es timate. Our results show that the two driving forces are of comparable magnitude and that the interpretation of the surface reconstruction p henomena given in terms of either purely charge or a purely adsorbate effect is an oversimplification. (C) 1998 Elsevier Science S.A. All ri ghts reserved.