When gold atoms are field-evaporated onto a gold surface in an STM in
an atmospheric environment, the deposited clusters can induce a large
strain on the substrate around them. Cluster atoms may spread by diffu
sion to relieve the strain. Sometimes, additional features involving t
he substrate atoms are formed which can be changed by the scanning dir
ection of the tip. For a surface which has not yet reached the thermal
equilibrium state, the tip scanning can occasionally induce large-sca
le structural changes of the surface.