EDS

EDS (Energy Dispersive Spectroscopy) on Vega-3 SEM.

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username: yadviga

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Here is a good overview of what EDS is: https://www.gems-inclusions.com/inclusions-studies/analytical-methods/sem-eds-wds-analysis/

Make sure your HV (accelerating voltage) is set between 15kV or 20kV.

Focus on the top of the sample and then bring it to 15mm working distance by adjusting the z axis (height) but keeping WD = 15. Be careful not to touch the gun/camera and do not use WD & Z on our computer as it does not accommodate all the chucks.  If the picture is somewhat in focus, it's good enough. 

Set the BI (Beam Intensity) to around 14 to 18. This gives you more counts in the spectrum. More counts means better statistics. You can see the counts per second (CPS) in the lower left corner of the EDAX software. Ideally you want several thousand.  If the count rate is low, increase the BI.

Once ready to acquire EDS, turn off the camera showing you inside the chamber. (Right-click in the image and switch off IR LED)

There should be another parameter at the bottom, usually next to cps labelled DT. This is Dead Time. It is possible to swamp the detector with x-rays and in this case the DT goes high.

Typically, try to keep the DT less than 50%. (20 to 50%)

Once ready, click "Point Analysis" tab, then click "Image Area".  This should allow you to choose which area to look at. You can either left click, hold and drag from left to right to get an area, or left-click and release to scan a single point. Once have the area selected, click on the " Collect Spectrum" tab.

The Edax system automatically identifies the peaks. I would always check what it is telling you.

You can also get quantitative numbers. These are around 1 to 10% relative to how much of the element is present.

You can also collect x-ray maps and line scans

Once done, just turn back the chamber camera by right-clicking and selecting IR LED. Proceed to unload your sample as usual on SEM. No special procedure is in place for turning off the EDAX system/software. 

For more details, there are some Basic SW instructional videos, as well as a user manual on the computer.