I am re-learning GSAS to bring Rietveld to my department (for the first time). We have an old Phillips Xpert.
I am trying to refine a quartz standard to acquire my profile and instrument parameters for this instrument and have yet to get my Chi^2 below 500. The instrument is not in my direct control. I have caught and asked them to correct a few problems already (dwell time too low, aluminum sneaking into the beam, etc...) and this has helped. I would like not to annoy them any more than I have too. At this point I think my high Chi^2s are mainly due to low angle asymmetric peaks that my fit is not able to copy - the asym is not terrible but may be messing me up. I am getting better results with peak profile functions 3 and 4, but unable to get Chi^2 below 500. My scans go up to 70 degrees 2theta. I would like to tell the people caring for the instrument that my problem is on their end, but I am not confident in my own refining skills to say this. When I work with the tutorials or standard data from my graduate school experiment I am ok - I think I am proceeding in a reasonable way, although I can get stuck here and there. I would like to find out if I am doing something incorrectly or if the problem is instrument related. I hate to bug one of you but wonder if I could get someone to look at my work?? Is there a better forum for asking for this kind of help? Kindest regards to all of you, Blaise * * * * * * * * * * * * * Blaise Mibeck Research Scientist Energy & Environmental Research Center University of North Dakota 15 North 23rd Street, Stop 9018 Grand Forks, ND 58202-9018 Phone: (701) 777-5077 Email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
