The cylindrical nanoscale density variations resulting from the interaction of 185 MeV and 2.2 GeV Au ions with 1.0 μm thick amorphous SiN :H and SiO :H layers are determined using small angle x-ray scattering measurements. The resulting density profiles resembles an under-dense core surrounded by an over-dense shell with a smooth transition between the two regions, consistent with molecular-dynamics simulations. For amorphous SiN :H, the density variations show a radius of 4.2 nm with a relative density change three times larger than the value determined for amorphous SiO :H, with a radius of 5.5 nm. Complementary infrared spectroscopy measurements exhibit a damage cross-section comparable to the core dimensions. The morphology of the density variations results from freezing in the local viscous flow arising from the non-uniform temperature profile in the radial direction of the ion path. The concomitant drop in viscosity mediated by the thermal conductivity appears to be the main driving force rather than the presence of a density anomaly.

We present the shape transformation of a single layer of Au NPs when embedded in, and at the interface of amorphous SiNx and SiOx (a-SiNx and a-SiOx) thin films upon irradiation with 185 MeV Au ions to fluences ranging from 0.3 to 30 × 10 13 cm -2 . Transmission electron microscopy (TEM) and high angular annular dark field (HAADF) microscopy were used to study the ion shaping process. The former allows us to follow the overall change in geometry, size and structure, while the latter reveals information about the relative position with respect to the interface. For Au NPs embedded in a single material, a lower elongation rate for a-SiNx was found in comparison to a-SiOx. When at the interface of the two materials, TEM reveals a preferential elongation towards a-SiOx. The latter demonstrates the use of a-SiNx for confining the ion-shaping process within an intermediate a-SiOx layer. The simulation of the temperature evolution during a single ion impact was used to understand the difference in elongation rates between a-SiNx and a-SiOx, as well as the asymmetric behaviour when located at the interface using the three-dimensional inelastic thermal spike (i-TS) model with bulk thermo-physical properties. The calculations show good agreement with the experimental observations and reveal a correlation between the thermal profile and the resulting NP geometry.

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Crystalline Ge and Si 1Àx Ge x alloys (x ¼ 0.83, 0.77) of (100) orientation were implanted with 140 keV Ge À ions at fluences between 5 Â 10 15 to 3 Â 10 17 ions/cm 2 , and at temperatures between 23 C and 200 C. The energy deposition of the ions leads to the formation of porous structures consisting of columnar pores separated by narrow sidewalls. Their sizes were characterized with transmission electron microscopy, scanning electron microscopy, and small angle x-ray scattering. We show that the pore radius does not depend significantly on the ion fluence above 5 Â 10 15 ions/cm 2 , i.e., when the pores have already developed, yet the pore depth increases from 31 to 516 nm with increasing fluence. The sidewall thickness increases slightly with increasing Si content, while both the pore radius and the sidewall thickness increase at elevated implantation temperatures.

Natural apatite samples with different F/Cl content from a variety of geological locations (Durango, Mexico; Mud Tank, Australia; and Snarum, Norway) were irradiated with swift heavy ions to simulate fission tracks. The annealing kinetics of the resulting ion tracks was investigated using synchrotron-based small-angle x-ray scattering (SAXS) combined with ex situ annealing. The activation energies for track recrystallization were extracted and consistent with previous studies using track-etching, tracks in the chlorine-rich Snarum apatite are more resistant to annealing than in the other compositions.