  The magnetism of quench-condensed Ru and Rh impurities and metal films on
Ag(100) and Pt(997) has been studied using x-ray magnetic circular dichroism.
In the coverage range between 0.22 ML and 2.0 ML no dichroic signal was
detected at the M3,2 absorption edges of Ru on Ag(100) at a temperature of 5 K
in the presence of an applied magnetic field. The same was found for coverages
between 0.12 ML and 0.5 ML of Rh on Ag(100) and Pt(997). It is concluded that
the magnetic moments of single impurities, small clusters of various shape and
monolayers of the 4d metals are below the detection limit of 0.04 muB per atom.
These results provide an unambiguous determination of the local magnetic moment
of Ru and Rh deposited on nonmagnetic transition-metal surfaces, which are in
contrast with theoretical predictions.
