Michael Shaffer, R.A
mshaf@oregon.uoregon.edu -or- mshaf@darkwing.uoregon.edu

Dear Shaf,
I have found that low-dose imaging aleviates the effects of both heating and charging. I use a 1.2 MV instrument, so our conditions might not be comparable to yours, but you might wish to try using a very low beam current and LoDose or other extremely sensitive film. As dictated by the no-free-lunch principle, you pay for the sensitivity with bigger grain. However, this is a quick and inexpensive thing to try. Good luck.

William Tivol
tivol@wadsworth.org

If your sample is small, you might want to use a one of these thermoelectric cooler/heaters. They are reversible, commercially available, and come in a variety of sizes and wattages. sorry, I don't have a source.

If you cool your sample with a larger LN2 system and you have a clean system, you should be able to cool and heat your sample with little condenstation problems. Don't cool down the sample until you are at your system's lowest pressure (probably less 10^-6 Torr or better in new SEM's) YOu will probably get a slight increase with heating the cooled area and the pressure rise will depend on the length of time that hte sample was cooled. However, remember that the gun area with ion pumps are differentially pumped with respect to the specimen chamber. The conductance to the sample from the gun area is extermely low. Furthermore, the ion pumps handle water vapor very well. Just make sure that your filament is off and that you reheat it a little bit more carefully next time you bring it up. You should be OK.

- -Scott Walck
walcksd@ml.wpafb.af.mil