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Division of Biogeoscience
Division of Geology and Geochemistry
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P.O. Box 64
(Gustaf Hällströmin katu 2a)
FI-00014 University of Helsinki

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Institute of Seismology

P.O. Box 68
(Gustaf Hällströmin katu 2b)
FI-00014 University of Helsinki

phone +358 294 1911 (university exchange)
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Send us email (firstname.lastname@helsinki.fi)

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Laboratories and Facilities

ELECTRON PROBE MICROANALYSIS LABORATORY

Photo: Pasi Heikkilä

Instructions for sample preparation prior to microanalysis

As soon as you know that electron microprobe work will be needed, ask Radoslaw Michallik for the next free slot in the instrument calendar. The queuing is based on the order of enrollment and it may take time before intrument time is available.

Make a thorough petrographic study of the samples to acquire a clear idea of the mineral phases that are present in the sample. Decide which phases you are interested in, and for what purpose you want to use the quantitative mineral composition. Based on the information in the literature, find out which elements are/can be present in the corresponding phases. For each mineral, list all major components and only the ones that you need for the study from the minor/trace components.

Study your thin section carefully and choose the regions that will proceed for the analysis. Note that maximum area of the electron optical images that is visible at once is 3*2 mm. From one thin section, choose a maximum of five Regions Of Interest (ROI) that contain all grains to be analyzed.

Make thorough pictures of the whole thin section as well as detailed close-ups of the ROI:s using both plain-polarized light and crossed polarizing filters. A suitable microscope for this purpose is located in Room B111. If needed, please contact Pasi Heikkilä for instructions in using the microscope camera. Print the maps to build a paper work-map for each thin section or put them into separate folders in USB stick, or bring your laptop.

Prepare up to five thin sections in total, this will account for a full week of continuous instrument time.

Clean the sample surface from fingerprints, dust, etc. using cellulose paper and ethanol from the laboratory. Contact Tuija Vaahtojärvi for the necessary equipment.

Keep the cleaned samples in a dust-free box to protect them from re-contamination, and give them to Radek Michallik or Pasi Heikkilä for carbon coating. Imaged samples should be given for the personnel at least one day before they are ready for the microprobe study.

The queuing system works as follows:

1. Measurement jobs appear into the queue in the order of enrollment.

2. Available measurement time up to one week in row. Please contact Radoslaw Michallik stating your name, phone number, preferred measurement time, and the purpose of analysis.

3. Only students who have taken the EMPA-course and associated practicals are allowed to book time. For Ph.D. students who do not know how to operate the instrument, please contact your group super-user.

4. This arrangement is subject to change.

Contact information: Radoslaw Michallik, Pasi Heikkilä