  The static and genuine structure of small rhodium and rhodium/tungsten
nanoparticles on an alumina support can be imaged with atomic resolution even
if single digit atom clusters are investigated. Low dose rate electron
microscopy is key to the achievement and can generally be applied to
investigate any similar material. In such conditions it becomes feasible to
identify the chemical composition of nanocrystals from quantitative contrast
analyses alone by counting atoms. The ability to fully characterize an
unaltered, initial state of the objects allows targeting structural excitations
or conformational changes induced by the electron beam itself. For the specific
case of catalytic Rh:W particles we stimulate a tungsten-promoted size
regulation mechanism in real time that is driven by Oswald ripening and can be
understood by a strong binding of tungsten atoms to the oxygen atoms of the
support, which builds up strain as the cluster sizes increase.
