  Auger Electron Spectroscopy, Low Energy Electron Diffraction and Scanning
Tunneling Microscopy have been used to study the atomic structure of a Zn
monolayer deposited on Ag(111) and Ag(110) substrates at room temperature. On
both faces, there is formation of a close packed monolayer of Zn covering the
entire substrate surface and giving rise to specific Moir{\'e} patterns. From a
comprehensive LEED and STM data analysis, we deduce that the Zn monolayer
adopts a (111) structure equivalent to a pure Zn layer rotated with respect to
the silver substrate, of about $1.5^\circ$ on the Ag(111) face and of about
$4.5^\circ$ on the Ag(110) face giving rise respectively to
($\sqrt{156}\times\sqrt{156})R18^\circ$ and c(12x6) superstructures.
