JEOL Probe Users Listserver
Moderator: Ellery Frahm, [log in to unmask],
Electron Microprobe Lab, University of Minnesota
Post a message: send your message to [log in to unmask]
Unsubscribe: send "SIGNOFF PROBEUSERS" to [log in to unmask]
On-line help and FAQ: http://probelab.geo.umn.edu/listserver.html
> One "simple" way for a user to get low totals on EMP is to have the
> sample out of focus during the analysis. We find some students
> focusing with BSE or in transmitted light instead of reflected
> light, or simply failing to check focus. With the SX-100 we use an
> autofocus system but some students turn off that option. Once the
> low total is obtained, one should immediately check in reflected
> light to see if the sample is still in focus after the analysis
> before moving the sample.
This researcher is experienced enough to check for all those problems,
and we're talking about bad results on a few specific samples (and not
others run at the same time) over several sessions. But I'll still
advice him to pay extra attention to these points next time.
> Another problem is that students (and sometimes their advisors)
> handle the sample, imparting oils to the carbon coat and causing
> charging that is difficult to see if the sample doesn't fluoresce
> (or we find that the user pays no attention to the flickering or
> moving luminescence!). One can find salt crystals in swirls in some
> cases. The only check for that is to repolish, reclean (a step that
> lots of folks forget), recoat, and then immediately reanalyze.
A possibility. I'll suggest that he repolish and reclean the samples
in case of their surfaces weren't totally clean.