Hi All
For a few weeks now I have been getting low totals (96-98%) on feldspars and glasses. This suddenly occurred while using the same standards and conditions (10nA; 2-10um defocus) I have always used. I have checked through backgrounds, matrix corrections and everything else I can think of. This only occurs with beam sensitive samples – it does not occur with olivine, pyroxene or garnet, which all give good analyses.
My gut feeling is that since a certain date I have been damaging my feldspars and glasses, its as though PFE is not setting the beam to defocus properly. Confusingly it does appear to defocus when I check using a fluorescent mineral but this is only visible with larger spots and is hard to assess down at the 2um level.
Has anyone any thoughts on this? Sound familiar? Am I missing something?
Please also check the attached screenshot . The beam conditions displayed via the Analyze! window on the left show a 2um defocus. The conditions displayed in the Automate! Window on the right show the same conditions without a defocus.
What are the two fields actually displaying here and which set of conditions actually apply to the analysed sample?
Richard