Ion Microscopy and Tomography

On the accuracy of element concentrations and masses of micron sized samples determined with the Heidelberg proton microprobe

Morphological and elemental characterisation with the high-energy ion-nanoprobe LIPSION

PIXE-STIM microtomography: Zinc and manganese concentrations in a scorpion stinger

Nanocomposite DNA hydrogels emerging as programmable and bioinstructive materials systems

Geant4 simulation of the new CENBG micro and nanoprobes facility

The nuclear microprobe is a microanalytical tool capable of quantitative studies of elemental distribution at the ppm level with a spatial resolution of the order of 1 μm. This sensitivity is adequate for most elements ofinterest, and the spatial resolution is acceptable for studies of elemental distribution in organs, tissues, and cells. The main techniques used in plant science are particle induced X-ray emission using protons, proton backscattering, scanning transmission ion microscopy, and particle induced gamma-ray emission. Specimen preparation is the most difficult part of analysis, and only cryotechniques are recommended presently for all types of microanalytical studies.

The high-energy ion nanoprobe LIPSION at the University of Leipzig has been operational since October 1998. The ultrastable single ended 3.5 MV SINLETRONTM accelerator supplies the H+ or He+ ion beam. A magnetic scanning system moves the focused beam across the sample. At present, a resolution of 150 nm in the low current mode and 300 nm at 5 pA could be achieved. The UHV grade experimental chamber is equipped with electron-, energy dispersive X-ray-, and particle detectors. They can be used simultaneously to analyse the sample by means of PIXE (particle induced X-ray emission), RBS (Rutherford backscattering) and in the case of thin samples STIM (scanning transmission ion microscopy). A goniometer allows the application of channeling measurements in single crystals in combination with these methods. The detection limits depend on the elements to be analysed and range from (1000⋯1) μg/g relative and (1⋯0.01) pg absolute. The analysis is nondestructive, but the sample has to be vacuum resistant. Applications of the nanoprobe in the field of semiconductor research, biomedicine, and archaeology will be described.

A data acquisition system for scanning microbeam analysis

We investigated element accumulation in the arbuscular mycorrhizal fungus Glomus intraradices. Fungal spores and mycelia growing in monoxenic cultures were analyzed. The elemental composition was quantified using particle-induced X-ray emission (PIXE) in combination with scanning transmission ion microscopy. In the spores, Ca and Fe were associated mainly with the spore wall, while P and K showed patchy distributions and their concentrations were correlated. Excess of P in the hyphal growth medium increased the P and Si concentrations in spores and increased the K/Ca ratio in spores. Increased P availability decreased the concentration of Zn and Mn in spores. We concluded that the availability of P influences the uptake and accumulation of several elements in spores. It is demonstrated that PIXE analysis is a powerful tool for quantitative analysis of elemental accumulation in fungal mycelia.

We present and discuss several modern optical methods based on elastic light scattering (ELS), along with their technical features and applications in biomedicine and life sciences. In particular, we review some ELS experiments at the single-cell level and explore new directions of applications. Due to recent developments in experimental systems (as shown in the literature), ELS lends itself to useful applications in the life sciences. Of the developed methods, we cover elastic scattering spectroscopy, optical tweezer-assisted measurement, goniometers, Fourier transform light scattering (FTLS), and microscopic methods. FTLS significantly extends the potential analysis of single cells by allowing monitoring of dynamical changes at the single-cell level. The main aim of our review is to demonstrate developments in the experimental investigation of ELS in single cells including issues related to theoretical “representations” and modeling of biological systems (cells, cellular systems, tissues, and so on). Goniometric measurements of ELS from optically trapped single cells are shown and the importance of the experimental verification of theoretical models of ELS in the context of biomedical applications is discussed.

The theories, modeling and experiments of the processes of secondary electron (SE) generation and SE usage in helium ion microscopy (HIM) are reviewed and discussed. Conventional and recently introduced SE imaging modes in HIM utilizing SE energy filtering and ion-to-SE conversion, such as scanning transmission ion microscopy and reflection ion microscopy, are described.

Quadrupole lens alignment with improved STIM and secondary electron imaging for Proton Beam Writing

In this paper a study on the ion transmission ratio of a nanoporous aluminasample is presented. The sample was investigated by scanning transmission ionmicroscopy (STIM) with different beam sizes. The hexagonally close-packedAl2O3 nanocapillary array, realized as a suspended membrane of 15 µm thickness, had porediameters of ∼ 215 nmand spacing of ∼ 450 nm. When the proton beam size was limited to a single domain, a peaktransmission ratio of 19% was observed as is expected from the geometry (∼19–20%). This result points out an almost perfectly parallel alignment of the capillarieswithin one domain. However, for larger beam scanning areas (sampling multipledomains) the transmission ratio was reduced to 5%. The STIM analysis over an arealarger than the typical domain size revealed an overall capillary angular spread of ∼ 2°.

Scanning transmission ion microscopy (STIM) has been applied to measure sputter yields of thin Kovar foil. The results have been found in very good agreement with values determined by the weight loss method, demonstrating STIM as a feasible alternative measurement technique for sputter yield estimation of thin material samples. Measurements have been carried out under normal xenon ion incidence for ion energies in the range between 100 eV and 1000 eV. In addition, sputter yields of Kovar bulk samples are reported. The data might be interesting for ion beam applications such as solar electric propulsion, in which materials with low sputter yields are preferred to ensure a long operational lifetime of the system components.

Scanning transmission ion microscopy (STIM) with a 3 MeV proton cyclotron beam