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• Any charging present on the surface of the sample will quickly degrade the quality of EDS spectra. In order to avoid charging: 
  • Use the lowest possible accelerating voltage that is appropriate for the material and elements of interest
  • Use an even smaller beam current
  • Ensure good electrical grounding using carbon tape,
  • Perhaps remove the sample to apply a thicker C coat to improve electron transport
  • Check to make sure that the sample isn't charging. You can often tell charging because there will be visual streaking on the image, however also you can look at a few things on the quantification and spectra. If you are seeing charging, let me know and I can give more specific results for how to try to remedy that.
    1. Check the mass% total, which should be around 100% for non-hydrous minerals (circled on attached image)
    2. Check the "Dwayne-Hunt limit" which is where the background on the spectra goes to 0. This should be around the energy of the accelerating voltage you are operating the microscope on, e.g. for 10 kV microscope setting, you should have a Dwayne-Hunt limit of 10 keV (circled on image)
    3. If there is charging, under Additional Settings, click A (circled on image) to make the software adjust the quantification down to the "effective high voltage"
• One proxy for quality of spectrum is to right click on the spectra and then select Logarithmic graph display, to make visible the background curve of the spectra. The background should taper smoothly to the highest values at the accelerating voltage used, e.g. if the microscope is being operated at 10 kV, the spectra should have smooth values up to 10 kV.
• The carbon peak can mainly be caused by sputtering: It can be disregarded in the Esprit software Sample Configurator menu. It will ignore the carbon peak in the quantification (aka it will know that the carbon is from the coating, not the sample). See page 27 of the Bruker Esprit Compact user manual
• PRECAUTION on carbon peak: Carbon peaks are tricky, carbon coating obviously will add to it, but so will just sitting in air.  Because C is so abundant in our environment, it is almost impossible to not have some C peak unless real precautions are taken to keep the sample from being exposed tot he environment.  The beam hitting the sample actually attracts all the hydro carbons in the chamber, so while the beam is one even more carbon (burn marks you see when you go from high to low magnification) is accumulating on the surface of the sample. 
• There are two quantification methods loaded. They can be changed by clicking the arrow on the Quantify button, and click Load.
  
• Check the non-normalized mass % totals, which ideally should be around 100% for non-hydrous minerals.
• In order to interpret mass percent oxides, it is helpful to have an idea of the anticipated mineralogy of the sample, then compare the compositions to the ideal stochiometric mineral compositions from an online mineral database such as Webminerals of Mindat.
• Technicians can share access to a number of technical books on electron microanalysis if desired.

III. Uploading Data to LIMS

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The SEMUploader application is used to format the tests for uploading to LIMS. It is available through the IODPLauncher application.

1. Select that sample you used to take the test. (You may also provide the sample's Text ID, if you have it)
   
   1. If uploading EDS data to a SEM test that was already uploaded, select the 'Existing SEM' tab.
2. When done selecting the sample, click 'Select' button.
   1. If uploading EDS data to an existing SEM test, select the SEM image you would like to upload EDS data for.
3. Enter the comments and initials and click 'Done' button.
4. Add as many SEM tests for the selected sample as you need.
5. You may edit records by going to the Records tab.
6. Make a folder for the all the EDS data you would like to upload. You may upload multiple EDS folders to a single SEM test.
   1. It is strongly suggested that the user and technicians upload to LIMS all formats available for the EDS analysis (Mapping mode - .bcf; Line Scan mode - .rtl; Objects mode - .rto; spectra for each mode - .spx; ESPRIT Compact standard Report - .rpt; Microsoft Word - .doc);
7. When finished adding all the SEM and EDS data for the selected sample, clicked the 'Finish and upload' button.
8. This will create a file in the C:\data\in folder (and any other folder you may add under the Settings tab)
9. Use the MUT application to upload this file. (Make sure MUT is configured to use C:\data\in and SEM is an active analysis)

IV. Preventative Maintenance (for technicians)

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