Hi Valerie, On Tue, Mar 2, 2021 at 10:48 AM Schoepfer, Valerie < valerie.schoepfer@usask.ca> wrote:

Hi,

I am using Larch XAS Viewer for the first time to analyze some Mo XANES data. It is fairly straightforward, however I am running into problems with energy calibration, which leads to problems with Linear Combination Fitting.

Right now, which is likely wrong, I’m calibrating the energy of a standard to the theoretical edge, then auto-aligning the samples to the standard. But how do reference foils fit in here? Reference foils don’t seem to be tied to the sample like they are in Athena. Should I be manually aligning?

Is there a general guidance or work flow?

It's possible that I do not fully understand the question or that this answer will veer a bit off the topic of your question. For sure, energies need to be aligned properly for any multi-spectra comparison or linear method to work well. But it should be that you will have groups of spectra that all share a consistent energy calibration, say from the same beamline/beamtime. If you do have a reference channel for every measurement, you can compare those reference channels. Ideally, these will not vary for every measurement - that would indicate a serious problem. So, I think you should be able to group spectra together as uniformly calibrated (hopefully all data from a day or more of beamtime at a particular beamline) and then make sure that the different groups of spectra. Does that seem reasonable? I have to admit that at my beamline I don't often have the luxury or need to run a reference foil for every scan, so we calibrate consistently ahead of time. I'm sure that leads to a bias in the software. I guess I forgot that Athena had the ability to read and tie a second spectrum as a "reference" and use that to auto-apply calibration. Is it generally necessary to calibrate many spectra individually, or do people find that doing them in a few large groups is sufficient? --Matt