Samples and sample holder for the SPELEEM microscope

The image above is of the sample holder (cartridge) used in SPELEEM. The sample is fixed into the sample holder with a Mo cap after gentle tightening of four symmetrically placed M2 screws. In both the preparation chamber and the main chamber, the sample can be heated to 400°C (radiative heating) with a filament built in the sample holder, or be heated to even higher temperatures (1300-1500°C) by e-beam bombardment. For a rough temperature measurement, there is a type-C thermocouple (W5%Re/W26%Re) spot-welded on the Mo ring under the sample. For a more accurate measurement, an infrared pyrometer is available.

Some general information on sample feasibility:

1)     Samples for measurements in SPELEEM must be conductive, otherwise charging problems occur hindering the measurements.

2)     Samples must be flat without any macro- or micro-size tips, as they may cause significant field emissions and eventually deleterious arcing.

3)     The size of the sample should generally not be less than 5×5mm2 and not more than 10×10mm2 (square) or Φ14mm (disc). The maximum thickness is 2.5mm. Caps with various openings (from 4 to 10mm) are available.

Note for non-standard samples:

  • In some special cases, very small samples (down to 2mm in diameter) can be loaded and studied at the expense of the spatial resolution.
  • Non-conductive samples can be measured with a specially prepared mask (metallic mesh)
  • In situ cleavage is also possible if it produces a smooth surface
  • All non-standard samples must be negotiated with the beam line scientist well in advance!