PREPARATION OF SAMPLES FOR ION MICROPROBE ANALYSIS –Updated March 11, 2008
1. Glass thin sections or cast epoxy mounts are recommended for most geological samples.
Please contact Wisc-SIMS staff if you need to use other types of sample mounting methods to see if it is suited for high precision stable isotope analyses.
Note that some mounting cements are not appropriate for SIMS analysis.
Wisc-SIMS routinely uses Buehler EpoxiCure® epoxy resin (20-8130), hardener (20-8132) and release agent (20-8185).2. IMS-1280 sample holder can accept following dimensions:
Dimension: 1 inch (~25 mm) round
Height: Less than 5mm is preferable, though max 12mm thick can be allowed.3. Surface should be polished and flat.
Typically, a final grit of 1 micron diamond is sufficient.4. Please engrave sample identification on the back of the section or cast a label within epoxy.
Magic markers should not be used as we may use ethanol to clean your sample before they will be coated.5. For high precision stable isotope analyses, sample preparation is critical to the precision and accuracy of data.
(1) Samples should be located within 5mm from the center of 1 inch section and not show significant surface relief or tilting (less than a few μm). If samples show significant polishing relief, it may be possible to fix it with a diamond lapping film.
(2) For measurement of high precision isotope ratios, relief must be at an absolute minimum. It is not always possible to judge relief by microscope and samples may require scanning by ZYGO white light profilometer or similar instrument with sub-micron resolution.
(3) A working standard must be mounted in each sample. Standards should be homogeneous, have known isotopic compositions, and match the mineralogy and major element composition. Please contact us if you do not have a suitable standard.
6. For other types of analysis, samples located within 8mm from the center can be analyzed.
7. Non-conductive samples should be either Au- or C-coated with thickness of ~30nm.
Thin slices of biological samples (≤1 μm) placed flat on Si-wafer can be analyzed without surface coating.8. Samples should have appropriate documentation for location of analysis spots.
Sometimes this is best done after Au coating. At minimum, reflected light microscopy is recommended at low and high magnification. (The IMS-1280 reflected light microscope field of view is 500 μm.) Other types of imaging or scales of examination depend on the details of each sample and may include SEM, BSE, CL, EBSD, EPMA, or laser confocal microscope.
Schematic View of CAMECA IMS-1280 Holder (1 hole)
© The Department of Geoscience, University of Wisconsin-Madison
Page created: Jan. 6, 2005; updated March 11, 2008. For comments and corrections please email.
