Before the experiment
Preparing for beamtime
Last updated
Preparing for beamtime
Last updated
Samples should be attached to the sample holder in a way that guarantees electric connection between sample surface and the sample holder, e.g. (depending on the sample type): with conductive glue, conductive scotch tape, spot welding of pieces of metallic foil, mechanically with screws and nuts, etc.
Sample holders: Omicron flag-type (molybdenum, copper, for some samples stainless steel is also OK, but not recommended).
Standard conductive silver glue: EPO-TEK H21D. Mix by weight 10 A : 1 B, recommended cure 150C / 1 hour (see more details).
Sample holders of several types and mounting options described above are generally available directly at the beamline. If you want to prepare your samples in advance, please check the following.
It is recommended to use sample holders with "ears" (see Fig. 1 "ears" are protrusions on the sides at the top edge of the sample holder). Without them sample holders will fall through the sample positions in the sample magazine under the heater. Except for this limitation, it is still possible to use sample holders without "ears", there is no fall-through problem neither in the load-lock nor in the manipulator.
Areas on the sides of the sample holder should remain clear, area available for sample mounting is shown with a red rectangle in Fig. 1. The sample itself and all holding/fixing components (e.g. glue, foils, screws etc.) have to be within this area.
Red cross marks ideal sample position. Thickness of the plate d is also very important (0.95 mm <= d <=1.05 mm).
For annealing at temperatures above 800C one should use high-temperature heating stage, in this case sample holder should have additional holes on the edges (red circles in the Fig. 1).
After all the modifications, especially if holes were drilled or screws used for sample mounting, check the back side of the sample holder. It should remain flat, nothing should stick out of it.
To avoid dropping top posts in the analysis chamber use a short piece of thin conductive wire and glue (or fix) its one side to the holder and another to the top post.
Make sure that all parts are conductive and the wire has no layer of insulation (for copper in kapton it is not always obvious). Otherwise, not grounded top post will be charging and its field will be deflecting emitted electrons and affect the measurements.
If you are not sure what is the best option for your particular sample, or need other help regarding sample mounting, please contact the beamline scientist (Andrei Varykhalov) for additional support.
Load-lock has a passive magazine with 3 sample slots mounted on a magnetic transfer rod. It can simultaneously accommodate up to: 2 samples with long (up to 10 mm) top-post OR 1 sample with long top post (10 mm) and 2 samples with short top-posts (5 mm)
There's a sample magazine for 3 sample slots in the preparation chamber. You can store there only sample holders with "ears". Magazine is mounted at certain angle, in order to fit the pitch angle of the wobble stick, and sample without notches will simply fall through.