Helium Droplet-Mediated Deposition and Aggregation of Nanoscale Silver Clusters on Carbon Surfaces

10 pags., 7 figs.We present experiments and calculations of the deposition and\udaggregation of silver clusters embedded in helium droplets onto an amorphous\udcarbon surface at room temperature. Calculations were also performed for\uddeposition onto a graphene surface. They involve potentials for the interaction of\udcarbon atoms with silver and helium atoms, provided by ab initio calculations. The\udnumerical simulations were performed for few-nanometer-sized silver clusters\udincluding up to 5000 Ag atoms and He droplets with up to 105 4He atoms. The\udfluid nature of the 4He droplet is accounted for by the renormalization of the He−\udHe interaction potential. The numerical results are consistent with deposition\udexperiments with an average number of 3000 Ag atoms per 4He droplet and\udindicate that the aggregation of the silver clusters on the carbon surface is\udmediated by secondary droplet impacts. They also reveal nontrivial dynamics of\udthe Ag clusters within the carrier droplet, showing a tendency to drift toward the\uddroplet surface. These findings are of relevance in understanding the\udheterogeneous deposition patterns (large ramified islands) developed for very large droplets with an average number of Ag\udatoms per droplet within the million range. Finally, the simulations of large (5000 atoms) Ag cluster deposition on graphene\udreveals strong superdiffusive behavior. In stark contrast, the diffusion is negligible on the amorphous carbon surface.This work has been partly supported by the Spanish Agencia\udEstatal de Investigación (AEI) and the Fondo Europeo de\udDesarrollo Regional (FEDER, UE) under Grant No.\udMAT2016-75354-P, the National Science Foundation (UnitedStates) under Grant Nos. CHE-1362535 and CHE-1664990,\udand the COST Action CM1405 “Molecules in Motion”\ud(MOLIM). M.P. thanks the finantial support by the AEI and\udFEDER under Grant No. FIS2014-52285-C2-1-P. M.P.d.L.-C.\udthanks Andreas W. Hauser, Nadine Halberstadt, and Marius\udLewerenz for very helpful discussions. The CTI (CSIC) and\udCESGA supercomputer facilities (Spain) are acknowledged for\udthe provided resources.Peer reviewe