Biology at microprobe

Micro-PIXE analytical technique provides elemental lateral mapping with micron lateral resolution simultaneously with with high elemental sensitivity of PIXE technique.

Methodology includes sample preparation, measurement and quantification. At JSI, the samples are produced by cryo-fixation and freeze-drying. The samples are enclosed within two Pioloform foils. During the measurements the samples are sprayed with low-energy electrons from a hot tungsten filament to prevent against charging.

Micro-PIXE setup

Fig. 1: Micro-PIXE setup at JSI. Proton microbeam: 3MeV, 200 pA, 1x1 mm2.

  • X-Ray detector: SiLi, 160 eV @ 5.9 keV.
  • X-Ray detector: HpGe IGLET, 150 eV @ 5.9 keV.
  • STIM detector: Canberra PD 300-19-100, 20 keV.
  • Proton dose normalization: Rotating vane.
  • Electron spraying is applied to prevent charging damage, samples are not C-coated.

Quantitative analysis is enabled by precise determination of the proton dose, applying in-beam chopping device positioned next to the collimating slits. Here the spectrum of the backscattered protons from the chopper is recorded in parallel with PIXE spectra in a list mode. During the off-line data processing, the proton dose as well as average thickness of the selected area of interest is extracted from the list-mode files simultaneously with PIXE spectra and loaded in GUPIXWIN program.

Currently active biology research subjects at MIC, performed in collaboration with external co-workers:

  1. Localisation of Cd, Zn, Pb and other elements in seeds and leaves of field-collected Cd/Zn hyperaccumulator Thlaspi praecox Wulfen from an area polluted with heavy metals near a lead mine/smelter (Vogel-Mikuš et al., 2007).
  2. Elemental redistribution in lichen Plasmatia Glauca after arsenate exposure (Mrak et al, 2007).
  3. Forestry: year pattern elemental distribution in larix, branch recovery and reaction zone mapping after cutting(unpublished, 2007).
  4. Penetration of TiO2 nanoparticles through biomembranes (unpublished, 2007).
  5. Buckwheat: elemental distribution in seed after Zn soil treatment (unpublished, 2007).
  6. Na, Mg, Br in halophytes (plants growing in saline-rich environment) (unpublished, since 2006).
Elemental maps of Thlaspi Praecox seed crosscut Visual light image of Thlaspi Praecox seed crosscut

Fig. 2: Elemental maps of Thlaspi Praecox seed crosscut. Scan area: 2x2 mm2. From Vogel-Mikuš et al., Environ. pollut. 147 (2007), 50.

Contact person:

Dr. Primož Pelicon

Last updated: 01/22/2014