Performing Integrated WDS and EDS Acquisition in PFE

[bgarcia]

OK, so John and I did some testing and found that JEOL eds is not returning any net intensities to PfEPMA, or rather the data file is not in the place it's supposed to be on the JEOL PC. Either way, I'll be doing some more investigation into 1) making sure the JEOL eds is functioning properly to begin with and 2) looking to see (with JEOL engineer) where the intensity files are kept.

Stay tuned!

[John Donovan]

OK, so John and I did some testing and found that JEOL eds is not returning any net intensities to PfEPMA, or rather the data file is not in the place it's supposed to be on the JEOL PC. Either way, I'll be doing some more investigation into 1) making sure the JEOL eds is functioning properly to begin with and 2) looking to see (with JEOL engineer) where the intensity files are kept.

Stay tuned!

To clarify a bit, the JEOL EDS interface is returning the EDS spectra as expected, but subsequently returns zero value intensities for net intensity requests (and no errors are reported).  At least for oxygen k-alpha. Ben will next try to get net intensities for other elements to see if it's a general issue.

Any ideas on what might be causing this?

[bgarcia]

Update: I've gotten the WDS/EDS integration package to successfully return intensities in PFE. JEOL installed a software update (1.19.0.1) for PC_EPMA.
 
I'm currently working through setting up my first "real" file with EDS enabled.

[Dan R]

I just got the EDS-WDS integration with my JEOL OEM EDS. So for clarity, when I get EDS net intensities back, where are the backgrounds coming from? 

That is are the default net intensities from the JEOL software correct?

[John Donovan]

Both the EDS net intensities and EDS background intensities are returned by the JEOL get EDS net intensity function call.

As to how accurate these net and background intensities are, I would have to refer you to someone who has tested the JEOL EDS system.  I believe Changkun Park at Korea Polar Reseach Institute has done some testing on his JEOL EDS system. Also Glenn Poirier at the University of Ottawa.

[John Donovan]

This is a new feature that we just added which allows one to plot WDS and EDS spectra together when using the integrated EDS and WDS acquisition feature in Probe for EPMA.

First acquire some WDS wavescans with the EDS acquisition turned on (see Acquisition Options dialog from the Acquire! window).  Might as well set the EDS acquisition time to use the sample acquisition time for the EDS acquisition runs the full time of the wavscan.

Then in the Plot! window check the Plot EDS Spectrum checkbox and for a WDS element, select corresponding Kilovolts for that element as shown here:



Then click the output menu:



Still a new feature, so let us know if there's anything that doesn't look right.  To see the WDS peak better you can check the No Peak Markers checkbox.

[dawncruth]

I'm finally getting to integrating the Thermo EDS and WDS setup, partially because one of our spectrometers went down. What better time to do this?

Three questions -- for now.
1. My EDS count times are longer than the Use Sample Counting time option. For example: I set up an olivine run which runs 264 seconds (PFE estimate), and the estimate given for EDS is 207 seconds. When I run the sample Thermo runs it for almost 6.5 minutes, so considerably longer.  I looked through the forum and couldn't find anything to explain that.

Note it also did this for my standards, which should only take 20 seconds total.
Note, I'm using a 20% deadtime

2. I started an automated olivine run with Si and Mg on EDS and the rest of the elements on WDS. It started great and then Si tanked by about 10 wt%. I re-standardized and cps/nA remained the same from my previous standard run. Usually, I'd repeak Si, but am not sure how to troubleshoot this as I didn't peak. I'm re-running the points to see what happens. Any thoughts?

3. I can't seem to specify O for stoichiometry calculations, when it was measured with EDS. I only have the EDS option.

 

[John Donovan]

I'm finally getting to integrating the Thermo EDS and WDS setup, partially because one of our spectrometers went down. What better time to do this?

Three questions -- for now.
1. My EDS count times are longer than the Use Sample Counting time option. For example: I set up an olivine run which runs 264 seconds (PFE estimate), and the estimate given for EDS is 207 seconds. When I run the sample Thermo runs it for almost 6.5 minutes, so considerably longer.  I looked through the forum and couldn't find anything to explain that.

Note it also did this for my standards, which should only take 20 seconds total.
Note, I'm using a 20% deadtime

The acquisition time is just an estimate and when EDS is involved the clock time is completely dependent on the actual dead times that occur.

One very important note: always use a *fixed* pulse processing time for EDS quant (that is, non-zero). If you have the "auto" pulse processing time selected in Thermo or PFE it will auto adjust based on the current count rate regardless of whether the faraday cup is in or out.  So when the cup comes out the pulse processing shifts to match the count rate, which messes everything up for EDS quant.

In other words be sure to set a fixed pulse processing time in PFE, then go to a sample, unblank the beam and set what the dead time in Pathfinder is.  Then enter that value when it asks you for the estimated dead time from the Automate window.

In practice is almost impossible to estimate this acquisition time accurately for EDS because the dead time depends on the sample and even more so on the beam current.

2. I started an automated olivine run with Si and Mg on EDS and the rest of the elements on WDS. It started great and then Si tanked by about 10 wt%. I re-standardized and cps/nA remained the same from my previous standard run. Usually, I'd repeak Si, but am not sure how to troubleshoot this as I didn't peak. I'm re-running the points to see what happens. Any thoughts?

I have absolutely no idea.

3. I can't seem to specify O for stoichiometry calculations, when it was measured with EDS. I only have the EDS option.

Are you trying to measure oxygen or calculate it by stoichiometry?  You can't do both things. 

That said you might be able to disable quant for measured oxygen and then add it in as an unanalyzed element for calculating by stoichiometry.

[dawncruth]

The acquisition time is just an estimate and when EDS is involved the clock time is completely dependent on the actual dead times that occur.

One very important note: always use a *fixed* pulse processing time for EDS quant (that is, non-zero). If you have the "auto" pulse processing time selected in Thermo or PFE it will auto adjust based on the current count rate regardless of whether the faraday cup is in or out.  So when the cup comes out the pulse processing shifts to match the count rate, which messes everything up for EDS quant.

In other words be sure to set a fixed pulse processing time in PFE, then go to a sample, unblank the beam and set what the dead time in Pathfinder is.  Then enter that value when it asks you for the estimated dead time from the Automate window.

In practice is almost impossible to estimate this acquisition time accurately for EDS because the dead time depends on the sample and even more so on the beam current.

Ok, that makes sense. We have a Thermo and the Time Constant (what I think you mean by pulse processing time) was set to auto. I'll have to play with it to see how to manage that.

Thermo users -- if y'all have tips on integrating EDS/WDS, I'd be most grateful!

Are you trying to measure oxygen or calculate it by stoichiometry?  You can't do both things. 

That said you might be able to disable quant for measured oxygen and then add it in as an unanalyzed element for calculating by stoichiometry.

That's exactly what I tried to do, disable quant. But when you disable quant - it doesn't allow you to select specify in the E/C properties window.

[John Donovan]

Are you trying to measure oxygen or calculate it by stoichiometry?  You can't do both things. 

That said you might be able to disable quant for measured oxygen and then add it in as an unanalyzed element for calculating by stoichiometry.

That's exactly what I tried to do, disable quant. But when you disable quant - it doesn't allow you to select specify in the E/C properties window.

Did you click on an empty row in the Elements/Cations dialog? 

[SteveSeddio]

1. My EDS count times are longer than the Use Sample Counting time option. For example: I set up an olivine run which runs 264 seconds (PFE estimate), and the estimate given for EDS is 207 seconds. When I run the sample Thermo runs it for almost 6.5 minutes, so considerably longer.  I looked through the forum and couldn't find anything to explain that.

Note it also did this for my standards, which should only take 20 seconds total.
Note, I'm using a 20% deadtime

2. I started an automated olivine run with Si and Mg on EDS and the rest of the elements on WDS. It started great and then Si tanked by about 10 wt%. I re-standardized and cps/nA remained the same from my previous standard run. Usually, I'd repeak Si, but am not sure how to troubleshoot this as I didn't peak. I'm re-running the points to see what happens. Any thoughts?

Hi Dawn,
I am happy to look at the Pathfinder data for items 1 and 2, if you want to zip the project and send it to me.
I may be able to discern what is going on.
-Steve

[John Donovan]

1. My EDS count times are longer than the Use Sample Counting time option. For example: I set up an olivine run which runs 264 seconds (PFE estimate), and the estimate given for EDS is 207 seconds. When I run the sample Thermo runs it for almost 6.5 minutes, so considerably longer.  I looked through the forum and couldn't find anything to explain that.

Note it also did this for my standards, which should only take 20 seconds total.
Note, I'm using a 20% deadtime

2. I started an automated olivine run with Si and Mg on EDS and the rest of the elements on WDS. It started great and then Si tanked by about 10 wt%. I re-standardized and cps/nA remained the same from my previous standard run. Usually, I'd repeak Si, but am not sure how to troubleshoot this as I didn't peak. I'm re-running the points to see what happens. Any thoughts?

Hi Dawn,
I am happy to look at the Pathfinder data for items 1 and 2, if you want to zip the project and send it to me.
I may be able to discern what is going on.
-Steve

I think the issue she was seeing is because she was using the "auto" time constant, which causes problems when doing quant and the faraday cup is being inserted and removed repeatedly.  Basically, the time constant is always changing during the acquisition and therefore the quant is affected.  The solution is to pick a fixed time constant for Pathfinder from the Probe for EPMA Acquisition Options dialog.