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Junlei Zhao1 Lu Cao3 Richard Palmer2 Kai Nordlund1 Flyura Djurabekova1

1, University of Helsinki, Helsinki, , Finland
3, University of Birmingham, Birmingham, , United Kingdom
2, Swansea University, Swansea, , United Kingdom

In this work, we study the mechanisms of growth of Ag nanoclusters in a solid Ar matrix and the emission of these nanoclusters from the matrix by a combination of experimental and theoretical methods. The molecular dynamics simulations show that the cluster growth mechanism can be described as "thermal spike-enhanced clustering" in multiple sequential ion impact events. We further show that experimentally observed large sputtered metal clusters cannot be formed by direct sputtering of Ag mixed in the Ar. Instead, we describe the mechanism of emission of the metal nanocluster that, at first, is formed in the cryogenic matrix due to multiple ion impacts, and then is emitted as a result of simultaneous effect of interface boiling and a spring force effect. We also develop an analytical model describing this size-dependent cluster emission. The model bridges the atomistic simulations and experimental time and length scales, and allows increasing the controllability of fast generation of nanoclusters in experiments with high production rate.

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