Clusters (3 - 50 nm) can be formed by an evaporation-condensation technique. A vapor produced by sputtering or thermal evaporation is ejected into an Ar-filled chamber. Collisions with the Ar atoms cause small, fairly monodisperse clusters to form. The clusters are collected on a cold finger and scraped into a die. The die is moved to a compaction chamber where the clusters are compacted to form a small pellet if desired.
One primary advantage of this technique
is that any material that can be sputtered can be made into clusters.
This is an UHV technique and the high monodispersity of the resulting
particles helps understand complex systems where magnetic properties
may go like d6 .
The chamber in which the materials are made is shown below. The sputtering source is on the left. The large chamber is where the coldfinger and scraper assembly are located, and the rightmost chamber is the compaction chamber. A glovebox fitted with a CF flange allows us to transfer samples without exposure to air.