[en] The precision of proton microprobe measurements of Sr in otoliths by proton induced X-ray emission (PIXE) has been improved significantly by use of a large area low resolution NaI(Tl) detector. This is achieved by scanning the sample simultaneously with a high resolution Si(Li) detector to measure the main constituent Ca and to confirm the absence of other elements in the counting window used by the large area detector. In our experimental setup the count rate for Sr was improved by a factor of 30. We took advantage of this to improve precision and achieve higher sample throughput in studies of diadromous fish, i.e. those whose life cycles may include both marine and freshwater stages

[en] 500 nm SiO₂ layers were implanted with 450 keV (F=3x10¹⁶ at./cm²) and 230 keV (F=1.8x10¹⁶ at./cm²) Ge ions at room temperature to obtain an almost constant Ge concentration of about 2.5 at.% in the insulating layer. Subsequently, the specimens were annealed at temperatures between 500 deg. C and 1200 deg. C for 30 min in a dry N₂ ambient atmosphere. Cross-sectional TEM analysis reveal homogeneously distributed Ge nanoclusters arranged in a broad band within the SiO₂ layer. Their mean cluster size varies between 2.0 and 6.5 nm depending on the annealing conditions. Cluster-free regions are always observed close to the surface of the specimens independent of the annealing process, whereas a narrow Ge nanocluster band appears at the SiO₂/Si interface at high annealing temperatures, e.g. ≥1000 deg. C. The atomic Ge redistribution due to the annealing treatment was investigated with a scanning TEM energy dispersive X-ray system and Rutherford back scattering (RBS)

[en] ²²Ne⁺ ions were implanted at 20 keV into wafer silicon and annealed at 1100 deg. C for 15 s (ΔT=5 deg. C/s) to study the formation of surface structuring. Ion beam analysis measurements revealed that the implanted neon was completely released into the vacuum during the thermal treatment. The surface became structured with the appearance of micrometer sized crater shaped pits with a typical depth of 45 nm. No uptake of carbon, nitrogen and oxygen from air by the specimens during transport and storage was detected making the newly formed structured silicon surfaces interesting for various industrial applications

[en] The concentration of elements in whole rocks and maps of their distribution in petrographic thin sections were determined using ion beam microprobe analysis. Lithium and B contents in rocks and minerals are measured using the ⁷Li(p,α)⁴He and ¹¹B(p,α)⁸Be reactions. X-rays are simultaneously detected for elements heavier than Na, including Cl, to corroborate microscopic mineral identification. The ion beam analysis data are integrated with observations under the petrographic and scanning electron microscopes, as well as analysis using X-ray fluorescence and the electron microprobe. Lithium, B and Cl can be used to assess volcanic and hydrothermal processes. In a study of 62 samples, Li, B and Cl increase proportionally with increasing silica content in fresh volcanic rocks from the Taupo Volcanic Zone in New Zealand. The median values for Li, B and Cl in rhyolites (SiO₂%=70-76%) are 35, 20 and 800 ppm (wt), respectively, and 19, 11 and 340 ppm (wt), respectively, for andesites (SiO₂=56-62%). Boron and Cl preferentially partition into the glassy matrix of rhyolite and andesite. In rhyolites, Li occurs mainly in minerals such as hornblende and biotite but resides in the glassy matrix of andesites. During hydrothermal alteration of volcanic rocks, Cl always partitions into hydrothermal solutions while Li and B are preferentially redistributed in the rock. As hydrothermal alteration proceeds, Cl in the rock decreases and B and Li increase proportionally, depending on the type of mineralization present and the temperature of alteration

[en] Thermal spray coatings applied with high velocity techniques such as high velocity air fuel (HVAF), produce coatings with superior quality in comparison to other traditional techniques such as plasma spraying. To date, our knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. To improve our understanding of these materials, especially of the surface oxide layer, Ni80/Cr20 HVAF thermally sprayed coatings were studied with scanning electron microscope, nuclear reaction analysis (NRA) and X-ray photoelectron spectroscopy (XPS). In particular, NRA and XPS were used to characterise the oxide composition that gives the coatings their excellent oxidation resistance. The surface oxide on the Ni80/Cr20 particles was found to be only 7 nm thick and enriched in SiO₂. A surprising finding was that the composition of the Ni80/Cr20 powder remained unchanged during the coating process despite the high velocity application with the HVAF method

[en] Nuclear microscopy was performed on shells of the Pacific oyster, Crassostrea gigas, to probe for heavy element impurities. For the studies 14 shells from the Auckland and the Marlborough Sounds region were chosen. In sections, the shells appear as opaque with white and grey zones, which are related to alternating layers of calcite and aragonite. Raster scans with 2.5 MeV protons over the sections (scan area 5 x 5 mm) were used in the experiment to measure trace elements in the ppm region using proton induced X-ray spectroscopy. Two dimensional maps and line scans revealed the presence of bromine in all shells investigated. Bromine was found to be related with the pattern of calcium. Hot spots of iron proved to be a common feature in the shells as well. In some shells, copper and zinc were also measured in hot spots of a few micrometers in diameter. Spatially resolved results on the micrometer level indicate the usefulness of nuclear microscopy for the detection of heavy elements in shells of the Pacific oyster

[en] Helium ion implantation into surfaces is used to form nanoporous cavity structures at high dose levels. Such cavity structures have unique features which offer potential for applications. For some applications, it is necessary to produce cavity layers that extend to the surface to enhance the ingress of selected dopant atoms. Here we investigate a method based on using a He-implantation protocol (employing a combination of He energies and doses) to produce nanoporous layers that intersect the surface. Titanium and other targets are implanted with He to several different dose levels and at several different energies. Implantations employing several different He energies in sequence are also investigated. Light atom depth profiles are determined by heavy ion elastic recoil detection analysis (HERDA). Non-resonant nuclear reaction analysis is used to verify the absolute concentrations of carbon, nitrogen and oxygen. RBS is used to depth profile the corresponding heavy target elements. Selected results, chosen to highlight the potential of HERDA and other ion beam analysis techniques in this type of study, are presented

[en] Helium ion implantation into surfaces can be used to form nanoporous cavity structures with unique features, of interest for applications. The ingress of desired dopant atoms into the material could be enhanced by producing cavity layers that extend to the surface. Ti and Co targets were implanted with He using pulsed plasma-immersion ion implantation (PI^3TM) and monoenergetic accelerator ion implantations. Spatially resolved elemental mapping of C, N and O, using microprobe nuclear reaction analysis was done with a scanned 20 μm diameter deuteron beam. This spatial resolution has enabled several important new results to be obtained. It is demonstrated for the two materials that He implanted surfaces take up more O from the atmosphere than unimplanted surfaces. In Ti, the nanoporous surface exposed by heavy ion damage in a prior heavy ion elastic recoil detection analysis measurement takes up twice as much O and over ten times as much N as the immediately adjacent undisturbed He implanted surface

[en] Highly swollen nanoporous layers produced in material surfaces by He implantation are of special interest for applications such as catalysis. Here we investigate whether nanoporous layers can be produced in the covalently bonded insulating ceramic, SiAlON. The retention of highly swollen porous structures in thinned TEM sections prepared from such hard brittle materials is particularly challenging. We have successfully prepared such sections both parallel to, and perpendicular to, the implanted surface. At intermediate doses the bubble structures are very similar to those found in metals. At high helium doses local swellings at depths around the mean projected range of the He ions (∼360 nm) are estimated to be well in excess of 200%. Bubble structures are stable under heating to temperatures up to 1200 deg. C. It is found that the highly cavitated layer is buried below a crystalline overlayer of compact SiAlON. This overlayer is sufficiently compact to resist the diffusion of gold from a surface layer to the cavities below

[en] Elemental composition and surface changes of thin high-temperature nitrided SiO₂ films were studied with ion microscopy using 0.92 and 1.4 MeV deuterium ions. Surprisingly, a non-uniform artificial pattern on the surface of samples annealed above 1150 deg. C was observed. Nuclear reaction microprobe analysis and scanning electron microscopy were applied to reveal the origin and composition of the pattern. The surface topology and the maps of the light elements were studied. The backscattered signals in the NRA data provided maps of Si and variations in the elemental compositions at the surface of the specimens. With both techniques, significant differences in the elemental make-up within the pattern were obtained. The light elements were found to be enriched differently in the centre of the non-uniform patterns and the surrounding ring-like structures, suggesting the formation of compounds of C, N, O and Si