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G. Szabo:
"Nano-hillock formation on the CaF₂(111) surface due to individual slow Au-cluster impacts";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien; 30.11.2021.

Nanostructuring of surfaces and subsequent tuning of their properties is an important toolkit in
nanoscience and surface physics. The formation of nano-hillocks induced by highly charged ions (HCIs) was
found to be mediated by a strong coupling of electronic excitations to lattice heating. For the comparison of
nanostructure formation between HCIs and heavy cluster ions, we utilize the CaF2(111) surface as a model
system. We present experimental evidence for a nanomelting process in the surface due to Au-cluster ion
impact in the keV regime. With the high momentum transfer of the clusters we circumvent the process of
electron-phonon coupling present after HCI impact. The melting then leads to rapid expansion of a
nanometric volume and subsequent quenching results in the formation of nano-hillocks. Not only is it
possible to create nano-hillocks similar to those found after irradiation with HCIs, but more importantly the
size can be finetuned by varying the cluster-size of the impinging particles.