Imaging water on Ag(111): field induced reorientation and contrast inversion.
Water adsorbed on Ag(111) at 70 K forms circular clusters that consist of six molecules. In scanning tunneling microscopy, this cyclic hexamer is imaged as a protrusion for voltages below V(SS)=-93 meV and as a depression for voltages above V(SS). The electronic density of states, however, increases around V(SS). We explain this counterintuitive result with the aid of calculated images by a change from constructive to destructive interference between different tunneling channels due to a field induced reorientation of the molecule under the tunneling tip.
Institut für Experimentalphysik, FB Physik, FU Berlin, Arnimallee 14, D-14195 Berlin, Germany. karina.morgenstern@physik.fu-berlin.de
Karina
K
Morgenstern
Jouko
J
Nieminen