Microsampling and Sample Preparation

Laser Ablation

Being part of the AXIOM lab the Laser Ablation unit (ESI NWR UP193fx) was installed in 2006. Its excimer source provides short (~3 ns) pulses of 193nm laser radiation which is used to ablate material from solid samples at spatial resolutions between 1-150 µm. The ablation chamber used (ESI NWR LFC) is capable to house samples as large as 15cm x 15cm x 2cm. Ablated material is transported by He cell gas (mixed with Ar prior to injection into the ICP). The sample aerosol is transferred to the MC-ICP-MS AXIOM and directly measured for isotopic composition.

Applications focus on the in-situ determination of U-series, Sr and B isotopes in marine carbonates.


Sample Preparation Devices

The available sample preparation techniques range from formatting of m-scale carbonate samples down to micro-milling of sub-mg powder quantities in µm-scale resolution and highly polished surfaces for the application of “non-destructive” analytical methods.

Amphibian chain saw

A hydraulic driven, water cooled diamond chain saw with varying blade length of up to 1 m for profile cuts and formatting of large sample blocks.  Implemented into the GEOMAR ROV Kiel 6000 system well targeted underwater sampling (“seafloor surgery”) is already conducted successfully down to 1000 m depth.

Mobile high precision disc saw

A mobile wet-cut diamond disc saw (maximum depth of cut: 4 cm, blade thickness: 1-2 mm) for precise subsampling and formatting of hand-sized samples, including slicing of coral drill cores for radiography. The water supply excludes recycling in order to minimize cross-contamination and uses depending on sampling purposes and required quality MQ-water, de-ionized or fresh water.

The next level of precision is available by a wet-cut horizontal microtome disc saw (hosted in RD-4), holding different blades for silicates and carbonates, providing precise slices down to 200 µm thickness in up to 1 inch diameter (one-way de-ionized water supply).

Handheld mini-drill and disc saw

Mainly used for dry mechanical cleaning of sample surfaces and subsampling in mm-scale a handheld drill and saw device provides mg-range powder quantities and clean fragments.

Computer controlled micro-mill

A binocular based, computer controlled micro-mill installed in a H14-filtering clean-air laminar flow box is used for powder sampling in sub-mg quantities at µm-scale resolution from embedded or mechanically mounted samples from sub-mm to 20 cm width (e.g. embedded fragments, laminated archives, coral drill cores).

The embedding  materials in use vary between classical low viscosity resin, high viscosity mounting wax (melting point approx. 70 °C) and putty-like cold-binding non-penetrative 2-component glue.

Vacuum embedding and polishing

For “non-destructive” EMP (Electron-Micro-Probe) and SIMS (Secondary Ion Mass Spectrometer) analyses flat and highly polished sample surfaces are required. For these usually small sample series we apply an adequate vacuum embedding device (e.g. for porous foraminifera) and polishing system, specialized on surface quality and less suitable for thin-section preparation routines.

Microwave digestion device

In order to dissolve bulk samples of heterogeneous composition (e.g. organic and/or silicate enriched) for radioisotope, elemental and isotope geochemical analyses we are hosting a microwave digestion system of the CAU (University Kiel) / Excellence Cluster (responsible: Dr. J. Scholten, GPI) within the GEOMAR counting lab facility for short-lived isotopes.