This is a good idea, and one that was used for a lot of the Fe oxidation state determination by EPMA studies by La position. I have always had a sneaking suspicion that this never worked as well it it should have because of the opposite effect to the one we observed with long wavescans. What we noticed is that with enough current (presumably if you will do fast scan you will need an appreciable current), you actually ablate the coating medium (we observed it on C coatings) and increase the counts (see attached). My concern is that the peak will be shifted in the same direction as the scan since there are more counts on the right side of the peak than the left, but I have never tested this myself (although I probably should have).
Also, it might take some cleaver programming to make this happen. As it is now the program has way too much overhead to be able to do a fast wavescan. Every point requires us to ask the machine to move the spectrometer to the new postions, then ask if the spectrometer is at the position, and then start the counting; moreover this has to be be one through an intermediary (PfE comm server) which adds to the time even more. Not a concern when your wavescans take 4 hours and you are spending 30 second per point, but I don't think that this will work with millisecond channel times. Maybe doing this is the peaksight software might make more sense since they can do this all ready, or figure out a way to ask peaksight to run the scan and cache the results and spit them out to our program at the end.. Might also be something useful to have in PfEPMA to make peak searches and wavescans faster in the software. Which bring me to another question, are the absolute spectrometer positions different in peaksight and PfEPMA? I have noticed slight shifts in the peak position when I determine them in PfEPMA and peaksight, does this have something to do with the verification sequence peaksight uses and PfEPMA presumably doesn't do? Or am I just imagining these shifts (which could very well be true).
phil