Tvw. Janssens et al., EFFECT OF ADSORBED POTASSIUM ON THE ELECTROSTATIC POTENTIAL ON RH CLUSTERS IN RELATION WITH PHOTOEMISSION OF ADSORBED NOBLE-GASES, The Journal of chemical physics, 101(4), 1994, pp. 2995-3000
A locally lowered surface potential develops around potassium atoms on
a transition metal surface. These potentials are accessible experimen
tally by measuring the ultraviolet photoemission spectra of adsorbed n
oble gases. We determine the potassium-induced change in electrostatic
potential on K/Rh clusters on the basis of calculated electronic stru
ctures using density functional theory. It appears that the calculated
potentials depend critically on the geometry of the cluster and may d
iffer substantially from the experimentally observed values. Clusters
that allow a substantial charge redistribution around the potassium at
oms give the best results. Another improvement is obtained from adding
the contribution of potassium atoms further away from the potential.
We also present theoretical evidence that the potassium-induced change
in ionization energy of Xe, Kr, and Ar on a Rh15K3 cluster is mainly
determined by the change in electrostatic potential. This provides sup
port for the use of photoemission of adsorbed noble gases as a probe f
or changes in local surface potential induced by adsorbed species.