PENEPMA simulation on oblique sample

[Facundo Bilbao]

Good day! I have a question regarding the simulation on Standard and CalcZAF.

If I perform a simulation with the tilted sample, will the program run a correction matrix or I will see the final measurement affected by the tilt?
I have seen on the help menu that there is a way to tilt the beam respective to the sample but I was not able to find it, so I made a .geo file with a sample with a 45º angle tilt, which I am updating it.

Thanks for the attention!

[John Donovan]

Good day! I have a question regarding the simulation on Standard and CalcZAF.

If I perform a simulation with the tilted sample, will the program run a correction matrix or I will see the final measurement affected by the tilt?
I have seen on the help menu that there is a way to tilt the beam respective to the sample but I was not able to find it, so I made a .geo file with a sample with a 45º angle tilt, which I am updating it.

Thanks for the attention!

Yes, you can describe such a "rough" sample surface using a .geo file.  Nice job.

However, if instead you want to model a flat tilted sample using PENEPMA you will have to specify the beam angle which is the Theta parameter in the GUI or the SDIREC parameter in the .in file, for both the standard and unknown.

Regardless, I suggest reading the PENEPMA documentation because if you are trying to model a normal EDS or WDS detector you will also need to change the detector geometry because the default detector geometry in PENEPMA is an annular detector (360 degrees full circle around the beam). 

Either way, you will have to run both a standard composition and a sample composition at their respective geometries.  From these simulations you can obtain a k-ratio that can be input into the CalcZAF software to calculate the matrix correction.

But an easier method is to simply use the Calculate Effective Take Off Angle K-Ratios window, which is accessed from the Run menu in CalcZAF:



But this calculation assumes that every element has the same effective takeoff angle.  But in reality, of course, each spectrometer will have a different effective takeoff angle depending on the orientation of that spectrometer relative to the sample tilt.

In Probe for EPMA one can specify an effective take of angle for each spectrometer (including EDS) based on the sample tilt (from the XY-Z stage coordinates), and calculate the matrix corrections as described here:

https://smf.probesoftware.com/index.php?topic=1579.0

I hope this helps answer your questions.

[Ben Buse]

Good day! I have a question regarding the simulation on Standard and CalcZAF.

If I perform a simulation with the tilted sample, will the program run a correction matrix or I will see the final measurement affected by the tilt?
I have seen on the help menu that there is a way to tilt the beam respective to the sample but I was not able to find it, so I made a .geo file with a sample with a 45º angle tilt, which I am updating it.

Thanks for the attention!

In PENEPMA input file can define angle of beam - default 180 going downwards

Code Select Expand

       >>>>>>>> Electron beam definition.
SENERG 30e3                      [Energy of the electron beam, in eV]
SPOSIT 0 0 1                     [Coordinates of the electron source]
SDIREC 180 0              [Direction angles of the beam axis, in deg]
SAPERT 0                                      [Beam aperture, in deg]


With monte carlo don't need matrix correction - it's an alternative to matrix correction - you'd compare the kratio for the flat model and the tilted model. So run simulations for flat and tilted unknowns and run simulations for the standards.

Alternatively can also do different beam angles in DTSAII but same would apply

For PENEPMA there is a paper showing the geometry https://academic.oup.com/mam/article/23/3/634/6899604 figure 3

In PENEPMA can look at primary photons hitting detector, and secondary fluoresced x-rays hitting detector - see pe-intens- file

In DTSA-II can look at changes in generation and emitted x-rays as well as secondary fluoresced

[John Donovan]

Good day! I have a question regarding the simulation on Standard and CalcZAF.

If I perform a simulation with the tilted sample, will the program run a correction matrix or I will see the final measurement affected by the tilt?
I have seen on the help menu that there is a way to tilt the beam respective to the sample but I was not able to find it, so I made a .geo file with a sample with a 45º angle tilt, which I am updating it.

Thanks for the attention!

In PENEPMA input file can define angle of beam - default 180 going downwards

Code Select Expand

       >>>>>>>> Electron beam definition.
SENERG 30e3                      [Energy of the electron beam, in eV]
SPOSIT 0 0 1                     [Coordinates of the electron source]
SDIREC 180 0              [Direction angles of the beam axis, in deg]
SAPERT 0                                      [Beam aperture, in deg]


With monte carlo don't need matrix correction - it's an alternative to matrix correction - you'd compare the kratio for the flat model and the tilted model. So run simulations for flat and tilted unknowns and run simulations for the standards.

Yeah, I wasn't sure why he asked about matrix corrections, since one must have the concentrations already to run the Monte Carlo model.  But I just assumed he wants to calculate a k-ratio using Monte Carlo and then apply different analytical matrix correction models to those k-ratios?

Another alternative I should have mentioned is that one can apply a Monte Carlo derived matrix correction to measured k-ratios in CalcZAF (or PFE) using the alpha factor method described here:

https://smf.probesoftware.com/index.php?topic=152.0

I still have about 8 servers at UofO still running MC simulations for binary compositions for the periodic table. I expect these calculations should be done next year some time (been running them for about 10 years now!).  Currently the matrix.mdb file (included in CalcZAF) has about 860K binary k-ratios.

See attached paper.