MERCURY ADSORPTION ON GOLD SURFACES EMPLOYED IN THE SAMPLING AND DETERMINATION OF VAPOROUS MERCURY - A SCANNING-TUNNELING-MICROSCOPY STUDY

To clarify the mechanism of mercury adsorption on gold surfaces thin e pitaxial gold films have been exposed to trace amounts of gaseous merc ury under laboratory conditions for different periods of time. The cha nges in the surface morphology of the thin films caused by the exposur e have been studied by scanning tunneling microscopy (STM). The evolut ion of the surface structures with time has been also investigated, in the course of a few days after the exposure. The adsorption of mercur y on the gold surfaces has caused drastic changes in the morphology of the surfaces. Pits and islands of 2 to 30 nm in diameter have appeare d on the surface, their size and density per unit area depending on th e amount of exposure to mercury. The formation of pits and islands fol lowed a certain path of events.