Nano-hillock formation on CaF₂ due to individual slow Au-cluster impacts

Abstract

We present a direct way to generate hillock-like nanostructures on CaF2(111) ionic crystals by kinetic energy deposition upon Au-cluster irradiation. In the past, the formation of similar nanostructures has been observed for both slow highly charged ions and swift heavy ions. However, in these cases, potential energy deposition of highly charged ions or the electronic energy loss of fast heavy ions, respectively, first leads to strong electronic excitation of the target material before the excitation energy is transferred to the lattice by efficient electron-phonon coupling. We now show that the kinetic energy deposited by slow single Au-clusters directly in the lattice of CaF2(111) leads to the production of nano-hillocks very similar to those found with slow highly charged and swift heavy ions, with heights between 1 and 2 nm. Our results are in good agreement with previous cluster irradiation studies regarding energy deposition and hence nano-structuring of surfaces, and we present Au-cluster irradiation as novel tool to fine-tune nanostructure formation.

Nd L-shell x-ray emission induced by light ions

“…Therefore, the x-ray emission studies are not only an important method for the experimental research on atomic collision mechanism and verification of the relative theory, but also has important significance for many basic research, for instance, the technique of particle induced x-ray emission (PIXE), diagnosis of dense plasma and laboratory astrophysics. [9][10][11][12] Multiple ionization state, which means more than one outer-shell electrons are absent at the moment of inner-shell x-ray emission, can be produced by the subsequent Auger transition and CK transition or simultaneous direct ejection of several electrons with relatively high probability in collisions of ion-atom by the strong Coulomb field of the projectile. [13,14] This action results in a reduction of the nuclear charge screening, and thus increases the binding energy of the residual orbital electrons, and alters the fluorescence yield of radiative transition.…”