MEX-1 Sample Preparation
Well-considered sample preparation is an important pre-beamtime task. It has the potential to critically influence the experimental outcome and success. In summary, the small vertical beam size coupled with small but noticeable beam motion demands highly uniform samples, as sample homogeneity is directly related to obtained data quality.
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Optimising powdered sample concentration for either transmission of fluorescence-mode measurements will maximise your data quality and consistency within your sample set.
Transmission : aim mode: for highly concentrated samples that can be diluted.
Aim for an edge step of approximately 1. An edge step below 0.3 will not be suitable, especially if you want EXAFS information. We use XAFSmass to estimate the edge step of samples based on their composition.
A guide to using XAFSmass for sample preparation is available here
A more modern version of XAFSMass is available for users familiar with python. It is available from github, pypi and anaconda. This is the recommended version of XAFSmass
Old version of XAFSMass for Windows can be downloaded from the link provided on this page. It is NOT recommended to use the old version of XAFSmass.
Fluorescence : aim mode: for minimally concentrated samples i.e. <2000 ppm
Aim to achieve a concentration of approximately 1000 ppm. Exceeding 2000 ppm will increase self-absorption effects. We commonly use cellulose to dilute samples to an appropriate concentration.
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