Andres RP, and
Dept. of Phys., Purdue Univ., West Lafayette, IN, USA.
Elastic properties of individual nanometer-size supported gold clusters.
Physical Review B-Condensed Matter, vol.51, no.8, 15 Feb. 1995, pp.5322-32.
An atomic force microscope has been used in the attractive (noncontact) force
mode to image individual nanometer-size Au clusters preformed in the gas
phase and deposited on a wide variety of atomically flat substrates. Using
this noncontact technique, it is possible to reliably image preformed
clusters in their as-deposited positions. This capability allows
nanoindentation studies to measure the mechanical properties of individual
nanometer-size Au clusters supported on atomically flat substrates and
permits a measure of the deformation of a nanometer-size cluster as a
function of the applied load. Applying a compression model to the deformed
clusters, an elastic modulus roughly 2/3 that of bulk Au is obtained for
annealed clusters with sizes between 3 and 18 nm. If the clusters are
unannealed, a significantly smaller elastic modulus is observed
(approximately 1/6 that of bulk Au). As the applied load increases beyond
approximately 20 nN, the data suggest that the yield point of an annealed Au
cluster can be exceeded and the atomic force microscope tip can fracture the
cluster. (44 References).