A high resolution ionoluminescence study of defect creation and interaction.

Helium ion microscopy has been used to investigate the ionoluminescence of NaCl. A 35 keV, sub-nanometer He(+) ion beam was used to generate ionoluminescence. The interaction of ionizing radiation with alkali halides leads to the formation of various crystal defects, in particular so-called color-centers.

Digging gold: keV He(+) ion interaction with Au.

Helium ion microscopy (HIM) was used to investigate the interaction of a focused He(+) ion beam with energies of several tens of kiloelectronvolts with metals. HIM is usually applied for the visualization of materials with extreme surface sensitivity and resolution. However, the use of high ion fluences can lead to significant sample modifications.

Imaging ultra thin layers with helium ion microscopy: Utilizing the channeling contrast mechanism.

Background: Helium ion microscopy is a new high-performance alternative to classical scanning electron microscopy. It provides superior resolution and high surface sensitivity by using secondary electrons.

Results: We report on a new contrast mechanism that extends the high surface sensitivity that is usually achieved in secondary electron images, to backscattered helium images.

Channeling in helium ion microscopy: Mapping of crystal orientation.

Background: The unique surface sensitivity and the high resolution that can be achieved with helium ion microscopy make it a competitive technique for modern materials characterization. As in other techniques that make use of a charged particle beam, channeling through the crystal structure of the bulk of the material can occur.

Results: Here, we demonstrate how this bulk phenomenon affects secondary electron images that predominantly contain surface information.

Directional liquid spreading over chemically defined radial wettability gradients.

We investigate the motion of liquid droplets on chemically defined radial wettability gradients. The patterns consist of hydrophobic fluorinated self-assembled monolayers (SAMs) on oxidized silicon substrates. The design comprises a central hydrophobic circle of unpatterned SAMs surrounded by annular regions of radially oriented stripes of alternating wettability, i.

Metastable droplets on shallow-grooved hydrophobic surfaces.

The equilibrium shapes of water droplets on shallow-grooved hydrophobic surfaces are studied experimentally. The dependence of the two final states, notably metastable Cassie-Baxter and Wenzel, on the underlying geometric pattern is analyzed and discussed. Surprisingly, in contrast to theoretical expectations, a significant portion of the droplets are in the Cassie-Baxter state.

Evaluation of genotoxicity and reproductive toxicity of silicon nanocrystals.

Silicon crystal 2-5 nm nanoparticles in the form of 1-5-μ granules in water suspension were injected intraperitoneally in a single dose to male F(1)(CBA×C57Bl/6) mice or to outbred albino rats on days 1, 7, and 14 of gestation. Silicon crystal nanoparticles in doses of 5, 25, and 50 mg/kg exhibited no cytogenetic activity in mouse bone marrow cells after 24-h exposure and in doses of 5 and 25 mg/kg after 7 and 14-day exposure. A 24-h exposure to silicon nanoparticles in a dose of 5 mg/kg significantly increased DNA damage (detected by DNA comet assay) in bone marrow cells.