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Clusters

The Clustering Process Seeded Supersonic Nozzle

Gas Aggregation
Electrospray Sputtering Laser Vapourisation (LVS)
Pulsed Arc Cluster Ion Source (PACIS)

Cluster Sources:Gas Aggregation Source

Gas Aggregation Source

One of the hot-oven techniques, gas aggregation is particularly efficient for the production of very large clusters. Used in the earliest spectroscopic studies of clusters it works by using an oven to evaporate the metal into a reservoir of pre-cooled carrier gas. By cryogenically cooling the reservoir with liquid nitrogen the metal vapour condenses, forming a highly saturated beam of clusters.

This source can produce very large clusters, often in excess of 20,000 atoms. Furthermore, it produces a continuous beam of clusters. Although it is possible to vary the cluster size distribution of this source within broad limits, the applications of this source are limited to metals with boiling points up to about 2000K. One advantage of this type of source is that low cluster temperatures (<100K) can be achieved.

The cluster formation in this source results from successive single atom collisions. As a result of this, the cluster growth is determined by collision statistics and the cluster distribution is a smoothly varying function of size.