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Slow highly charged ions (HCI) were utilized successfully for the formation of various nanostructures in the surfaces of different materials. The creation mechanism of HCI-induced nanostructures was intensively studied in alkali- and alkaline-earth fluorides. Here, we are investigating another type of fluorine-containing ionic crystals of different crystalline and electronic structure, namely lanthanum fluoride, LaF 3. The single crystals were irradiated with slow (eV-keV) highly charged xenon ions from an Electron Beam Ion Trap. After irradiation, the crystals surfaces were investigated by scanning force microscopy. The measured topographic images show nanohillocks emerging from the surface. These nanostructures were observed only after exceeding a well-defined threshold in the potential energy. The role of ion parameters for nanohillocks formation as well as a comparison with results for swift heavy ion irradiations of LaF 3 single crystals are presented. Furthermore, the similarities and differences between LaF 3 and other ionic fluoride crystals, in the creation of surface nanostructures, are discussed. [ABSTRACT FROM AUTHOR]

GaP single crystals were irradiated with slow highly charged ions (HCI) using 114 keV 129 Xe (33–40)+ and with various swift heavy ions (SHI) of 30 MeV I 9+ and 374 MeV–2.2 GeV 197 Au 25+ . The irradiated surfaces were investigated by scanning force microscopy (SFM). The irradiations with SHI lead to nanohillocks protruding from the GaP surfaces, whereas no changes of the surface topography were observed after the irradiation with HCI. This result indicates that a potential energy above 38.5 keV is required for surface nanostructuring of GaP. In addition, strong coloration of the GaP crystals was observed after irradiation with SHI. The effect was stronger for higher energies. This was confirmed by measuring an increased extinction coefficient in the visible light region. [ABSTRACT FROM AUTHOR]

Abstract: The creation of surface nanostructures in BaF2 (111) surfaces was studied after irradiation with slow highly charged Xe ions from the Dresden-EBIT (electron beam ion trap). After irradiation, the crystals were investigated by scanning force microscopy (SFM). Using specific ion parameters, the topographic images show nanohillocks emerging from the surface. Additionally, we used the technique of selective chemical etching to reveal the lattice damage created by ion energy deposition below and above threshold needed for surface hillocks formation. The role of both potential and kinetic energy as well as a comparison with results for swift heavy ion irradiations of BaF2 single crystals are presented. [Copyright &y& Elsevier]

Alloys of composition Sn-8.5Sb-5.5Cu (in atomic percent) were rapidly solidified by a melt-spinning technique. The samples were irradiated at room temperature with GeV uranium ions of fluences between 9×108 and 9×1011 ions cm-2. X-ray diffraction analysis revealed the formation of a new-phase Cu11Sb3 as well as a reduction in the axial ratio (c/a) of the matrix (β -Sn) indicating the regular re-arrangement of atoms. Scanning force microscopy showed no surface topographic changes with the ion fluence. The mechanical properties (Young's modulus and hardness) of the irradiated alloys were studied as a function of ion fluence. The radiation-annealing process is discussed in terms of the evolution of both resistivity and hardness as a function of ion fluence. [ABSTRACT FROM AUTHOR]

Abstract: Irradiation of crystalline solid targets with swift heavy ions can lead to the formation of latent tracks in the solid and the creation of (mostly-hillock type) nanostructures on the surface. Recently similar surface modifications with nanometer dimensions have been demonstrated for the impact of individual, very slow but highly charged ions on various surfaces. We will review the current state of this new field of research. In particular we will discuss the circumstances and conditions under which nano-sized features (hillocks or craters) on different surfaces due to impact of slow highly charged ions can be produced. The use of slow highly charged ions instead of swift heavy ions might be of considerable interest for some practical applications. [Copyright &y& Elsevier]

Abstract: We present first results on the generation of surface nanostuctures by slow HCI on cleaved CaF2 (111) surfaces. The CaF2 single crystals were irradiated with slow (v ≪1a.u.) Xe44+ HCI from the Heidelberg-EBIT. Like for other ionic fluoride single crystals, ion-induced surface structures in CaF2 are known to be stable in atmospheric conditions at room temperature. After irradiation the crystals were investigated by scanning force microscopy. Topographic images reveal the generation of nanometric hillocks protruding from the surface. The number of hillocks per unit area is in agreement with the applied ion fluence. A discussion of the role of the potential energy as well as a comparison with observations for swift heavy ion irradiations of CaF2 single crystals are presented. [Copyright &y& Elsevier]