Analytical facilities

• Electron microprobe analysis is designed for chemically analysing very small areas of solid samples
• Analytical accuracy is in the order of +/-1% (relative), detection limits are typically >50 ppm
• Elements with Atomic numbers >4 (Be) can be detected
• Our JEOL 8230 is equipped with five wave-length dispersive spectrometers (WDS) and an energy-dispersive spectrometer (EDS)
• Secondary electron images (SEI), back-scattered electron images (BSE) in COMPO and TOPO mode and Cathodoluminescence imgages (CL) can be used to characterize the surface and compositional homogeneity of solid samples

For access to the Tabletop Scanning Electron Microscopes PhenomXL and TM3030+ please contact PD Dr. Benjamin Walter.

TXRF is a special EDXRF method. The geometric setup allows for a very short distance between sample and detector, resulting in very high detection efficiency for the fluorescence radiation. This leads to an improvement of sensitivity by several orders of magnitude compared to conventional XRF techniques. Elements with atomic number of >13 (alumina) can be detected without the need for a vacuum. We use a S2 PICOFOX benchtop TXRF system from Bruker AS equipped with a Mo X-ray tube, operated at 50 kV and 600 µA. For analysis, a few mg of powdered sample material or a few µl of liquid sample are sufficient. Depending on the nature of the samples, detection limits (depending on the matrix) are in the low- to sub-µg/g range for solid samples and in the low- to sub-µg/l range for liquid samples.

For access to the TXRF lab please contact apl.-Prof. Michael A. W. Marks.

We work with the ion chromatographs Compact IC Flex and Compact IC Plus from Metrohm equiped with an automated filtration unit and an autosampler for analysing cations (Li, Na, K, Mg, Ca, Sr, Ba) and anions (fluoride, chloride, bromide, nitrate, sulfate, phosphate) in liquid samples (e.g., natural surface waters, mine waters, soil waters, and leaching solutions). Detection limits are in the low- to sub-mg/l range.

For access to the IC lab please contact apl.-Prof. Michael A. W. Marks. 

CIC is a combined system of combustion digestion (pyrohydrolysis) and ion chromatography and is used for the simulataneous determination of halogens (F, Cl, Br, I) and sulfur in solid samples (e.g., whole-rock powders, soils, mineral separates). The analysis via combustion requires 5-10 mg powdered sample material, which is then heated to 1050°C in an Ar/H2O atmosphere. The halogen loaded vapor is then collected and condensed via a cooling system (absorption module) and subsequently analysed by ion chromatography. For analyses, we use a Metrohm Compact IC Flex chromatograph, combined with a Metrohm Absorber module, a combustion oven and an autosampler for solid samples (Analytik Jena).

For access to the Combustion IC lab please contact apl.-Prof. Michael A. W. Marks.

We investigate microvolumina of fluids entrapped in minerals during growth and alteration processes by microthermometry. Temperatures of phase transformations observed in fluid inclusions reflect the nature and characteristics of the fluid from which the host mineral precipitated or the conditions under which the host mineral underwent alteration. We use a heating-freezing stage coupled to a polarization microscope. For further investigation of fluid inclusions, we have full access to the in-house Raman spectroscopy, ion chromatography and TXRF laboratories.

Cathodoluminescence (CL) microscopy is used for the textural analysis of minerals and phases showing luminescence like carbonates, quartz, fluorite and others. The hot cathode method makes it possible to analyze minerals having low-medium amounts of iron, which is not possible with a normal cold cathode device. We use a HC6-LM CL microscope from LUMIC, which works under vacuum (5x10^-4bar) with an acceleration voltage of around 14kV and a beam current between 0.15 and 0.3 mA. The device is attached to a OlympusU_P4RE microscope with an Olympus XC10 Camera

For access to the Cathodoluminescence lab please contact PD Dr. Benjamin F. Walter.