Chemistry Reference
In-Depth Information
Fig. 3 The two general techniques used to synthesise nanoclusters are (a) the 'top-down'
approach and (b) the 'bottom-up' approach
1. The 'top-down' approach utilises bulk material (metal powder, rods, blocks,
etc.) which is broken down by physical methods to smaller architectures on the
nanometre scale. Methods that have been applied to the synthesis of gold
nanoclusters following the 'top-down' approach include lithographic techniques
[
62
,
63
], mechanical methods such as ball milling [
64
], thermal methods such as
laser ablation vaporisation [
65
-
67
] and chemical methods such as ligand etching
[
68
-
70
]. Issues concerning the top-down approach include difficulties with
reproducibility, polydispersity and the need to require mechanical equipment
and instrumentation which may add time and costs to the synthesis.
