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Sample Preparation and Characterisation Laboratories

Preparing the Gemini VII surface area and porosity analyser for sample loading. To the left is the vacuum and flow degasser used to remove volatiles prior to BET analysis.

Preparing the Gemini VII surface area and porosity analyser for sample loading. To the left is the vacuum and flow degasser used to remove volatiles prior to BET analysis.

Controlling and acquiring spectra using the LILBID mass spectrometer.

Controlling and acquiring spectra using the LILBID mass spectrometer.

Interplanetary and Interstellar Dust

Refractory cosmic dust analogues, such as mineral, polymer or metal powders, are prepared and characterised using a range of techniques, including:

  • Planetary Ball Milling

    Using a Retsch PM100 CM planetary ball mill, with zirconium or hardened steel milling chambers and balls, we can produce ultrafine sub-micron and micron-scale powders for subsequent metal coating and acceleration as cosmic dust analogues, or use in hydrothermal experiments which seek to simulate the subsurface environment of Enceladus.

  • Pycnometry

    Our Micromeritics Accupyc II 1340, with 1 cc insert, can measure the bulk density of small solid or powder samples. Surface Area and Porosity Analysis - a Micromeritics Gemini VII 1390t enables the rapid determination of sample surface areas and pore distributions. A Micromeritics VacPrep 061, vacuum and flow sample preparation system allows volatile contaminants to be removed from samples prior to surface area or porosity analysis.

  • Composition

    A Linseis PT 1000 thermogravimetric analyser, with optional vacuum system, enables the temperature-dependent masses of samples to be measured, providing information about sample composition - such as volatile and organic composition, mineral phases, and melting point, as samples are heated to up to 1100 °C under vacuum or inert gas flow.

Thus far, samples of a range of minerals, including antigorite, olivine (San Carlos, peridot), opal, muscovite, orthopyroxene, silica and diopside, as well as CV3 ( Allende) and CO3 ( NWA 13178) meteorites have been powdered and characterised to produce samples for use with impact ionisation mass spectrometers, impact and ablation experiments. After these dust analogue ensembles (powders) have been produced, they are then coated with a thin (<15 nm) layer of conductive material, typically a metal such as silver, palladium or platinum. This enables the grains to charge and accelerate at facilities such as U. Stuttgart's electrostatic accelerator.

A scanning electron microscope image of silver-coated S. thermophilus bacteria (larger spheres) surrounded by pure silver microparticles.

A scanning electron microscope image of silver-coated S. thermophilus bacteria (larger spheres) surrounded by pure silver microparticles.

Dust from Icy Moons

As described in further detail here, our LILBID mass spectrometry concentrates on samples that are, or could be, found in water-ice dominated particles ejected from icy moons such as Europa or Enceladus. Solutions, prepared as analogues of the icy material, containing salts to mimic subsurface ocean compositions, organics, and biological material can then be studied to predict the appearance of their impact ionisation mass spectra.

The biological components can include non-pathogenic bacteria such as S. thermophilus, S. alaskensis and B. subtilis, which we culture and grow in our biochemistry laboratory. Whole bacteria can then be used as templates for metallation and use in accelerator experiments, lysed for use in the LILBID mass spectrometer, or undergo extraction and purification so that e.g. proteins, fatty acids, amino acids and other cell components can be studied separately.

A student being shown how to count bacterial cells using an optical microscope and a cell counting chamber.

A student being shown how to count bacterial cells using an optical microscope and a cell counting chamber.

Bacterial samples, either provided by collaborators, purchased or collected during field trips, are grown under optimal conditions, as well as under conditions which are representative of the subsurface or surface environments of Enceladus or Europa. Growth is monitored via cell counting, used to calibrate spectrophotometric turbidity measurements.

To simulate better the harsh surface conditions found on Jupiter's moon Europa, samples have been irradiated with >keV energy electrons at the Leibniz-Institut für Oberflächenmodifizierung in Leipzig. The samples are then processed and analysed using LILBID and the results compared with those from unirradiated bacteria.

Location

The laboratories are based in Building B (B.237, B238) on the GeoCampus in Berlin Lankwitz. Please contact the laboratory manager, Dr. Jon Hillier, for further info.

Contact

Dr. Jon Hillier (phone +49 30 838 70822, j.hillier@fu-berlin.de)

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