Helium Droplet Assembled Nanocluster Films: Cluster Formation and Deposition Rates

Abstract

This article examines the formation of nanoclusters by superfluid helium droplet assembly and the rates at which they can be deposited. A model of this process is presented that takes into account the hydrodynamic properties of droplet nozzle, the helium droplet size distribution, the dopant incorporation and condensation process, and the transport and collision of the doped droplet beam with a substrate. The results of this model are validated against measured magnesium cluster deposition rates produced in a droplet beam over a range of nozzle pressures and temperatures. This effort illuminates the connection between cluster deposition and the hydrodynamic state of a helium droplet beam, as well as, demonstrates the feasibility and level of control that can exist in creating cluster-based films by helium droplet assisted cluster assembly.