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71
EPMA Standard Materials / Re: Unsure of Analysis Standard
« Last post by Probeman on July 12, 2024, 07:03:24 AM »
Quote from: mjpavel on July 09, 2024, 01:35:38 PM
As it turns out the weight %'s they reported are using oxford's factory quant standards inside Aztec...I'm at a bit of a loss what to even do with this block of material now

I talked with our single crystal diffraction expert, Lev Zakharov, and asked him if he could determine the SiC stoichiometry if the materials was single crystal and he responded:

Quote
To get the full structure based on X-ray diffraction single crystal method. I can do. Stoichiometric will went out automatically based on the single crystal structure. Powder X-ray diffraction can be used but you need to have powder diffractions from the pure Si and C standards.

Then I asked about the accuracy of such methods and he responded:

Quote
I have never been evaluated and never seen such evaluations. From a general consideration I think i t seems to be around 3%-5% if quality of a crystal used for data collection is good.  Typically, 3%-5% is a difference between intensities of symmetrical X-ray diffraction reflections which should be the same based on symmetry.
72
EPMA Standard Materials / Re: Unsure of Analysis Standard
« Last post by mjpavel on July 12, 2024, 06:53:02 AM »
That's what were trying to do next...What a headache it's been
73
Cameca / very low counts in standards
« Last post by Alejandro Cortes on July 12, 2024, 06:49:37 AM »
While our Jeol is being repaired I decided to venture in the cameca instrument we also have for the first time. I am experiencing issues with counting on standards. Peak positions are found effectively but retrieving less than 2k cts. While for Si (Spec 4 TAP-Albite) and Na (Spec 2 LTAP-Albite) this is fine, Al is really bad (Spec 4 TAP - Corundum). I though this had to be with column alignment but then why is it good for some elements and bad for others... Any input will be greatly appreciated.
 
74
EPMA Standard Materials / Re: Unsure of Analysis Standard
« Last post by crystalgrower on July 11, 2024, 05:09:11 PM »
Send it back for a full refund?
75
Probe Image / Re: Latest version changes for Probe Image v. 1.4.7
« Last post by John Donovan on July 11, 2024, 01:27:31 PM »
We don't usually post about bug fixes, but the latest Probe Image 1.4.7 fixes a small bug when the user enters negative stage positions by hand (keyboard).

See here for the v. 1.4.7 download ZIP:

https://probesoftware.com/Update.html
76
DTSA II / Re: "Strip background" by using Clayton's algorithm
« Last post by Nicholas Ritchie on July 11, 2024, 11:38:59 AM »
This is how I implemented Clayton's algorithm

Code: [Select]
static public class Clayton1987PeakStripping extends PeakStripping {
      public Clayton1987PeakStripping() {
         super("Clayton - 1987", "Clayton E, Duerden P, Cohen DD. Nuclear Instrum Methods B22:91, 1987");
      }

      private final int MAX_ITERATIONS = 1000;

      @Override
      protected void initializeDefaultStrategy() {
      }

      @Override
      public ISpectrumData computeBackground(ISpectrumData src) {
         final double[] ch = SpectrumUtils.toDoubleArray(src);
         double delta = 0.0, delta0 = -Double.MAX_VALUE;
         for (int iter = 0; (iter < MAX_ITERATIONS) && (delta > (1.0e-6 * delta0)); ++iter) {
            delta = 0.0;
            for (int i = ch.length - 2; i >= 1; --i) {
               final double m = 0.5 * (ch[i + 1] + ch[i - 1]);
               if (ch[i] > m) {
                  delta += ch[i] - m;
                  ch[i] = m;
               }
            }
            if (delta0 == -Double.MAX_VALUE)
               delta0 = delta;
         }
         return new DerivedSpectrum.BasicDerivedSpectrum(src, ch, "Clayton[" + src.toString() + "]");
      }
   }

So it uses a dynamic test to determine the number of iterations.

On the other hand, the mechanism that DTSA-II uses to fit spectra does not depend on the peak being a Gaussian shape so it might work just fine on your spectra.
77
DTSA II / "Strip background" by using Clayton's algorithm
« Last post by ZhaiQ on July 11, 2024, 11:06:59 AM »
Hi all,

I am new to DTSA software and I am trying to use it to analyze our EDS spectra. The X-ray peak we are looking for has different shape from normal characteristic peaks. It is not Gaussian (even after the convolved with the detector). In this case, the background subtraction is very important for us to eliminate the bremsstrahlung and then compare the experimental data with theoretical results.

When I read the DTSA document, I found the "Strip background" algorithm comes from "A DISCUSSION OF PIXAN AND PIXANPC: THE AAEC PIXE ANALYSIS COMPUTER PACKAGES" by Clayton. And after reading the original paper I noticed the number of iterates N will affect the final results.

My questions is how does DTSA determine the number of iterates N? Is it a fixed number? Thank you very much!
78
DTSA II / Re: adding oxford instruments Ultim Max detector
« Last post by Nicholas Ritchie on July 11, 2024, 09:23:12 AM »
I'm sure someone at the detector vendor does but I've never been able to pry this information out of them.  They seem to view coatings and dead-layers as trade secrets.
79
Probe Software Inc / Re: Probe Software YouTube Channel
« Last post by John Donovan on July 11, 2024, 09:18:38 AM »
We're getting quite a lot of views on our Probe Software YouTube channel:

https://www.youtube.com/@ProbeSoftware

Also, be sure to update your Probe for EPMA software so you and your users can take advantage of the new button links to specific video tutorials in the Basic EPMA window:

https://probesoftware.com/smf/index.php?topic=1267.msg12714#msg12714

In the mean time we're looking for suggestions for more video tutorials on our Probe Software applications. Here's a list of possible ideas:

Commonly used functions available in Acquisitions Options
Using PFE for instrument specification testing (e.g. beam stability, stage reproducibility, etc.)
Using calculation options to include unanalyzed elements in the matrix correction
Calibrating dead times and the picoammeter using the constant k-ratio method
Checking k-ratio agreement between spectrometers using simultaneous k-ratios
Applying different background models to off-peak elements using fitting methods in the Plot! window
Using TDI correction methods for points (and a separate video for TDI quant maps)
Using empirical APF factors for light elements
Using the blank correction method in PFE
Interpreting detection limits and analytical sensitivity calculations
Creating presentation quality output for quant maps using CalcImage and Surfer
Using the PENEPMA and PENFLUOR calculations in the Standard application
Calibrating beam and stage scans
Setting up PFE on an off-line computer for data reprocessing or on a laptop or other computers in simulation mode for teaching

Any other ideas for more videos?
80
DTSA II / Re: stoichometric oxygen and carbon by difference
« Last post by Ben Buse on July 11, 2024, 08:55:36 AM »
To further expand on this

I've now quantified Smithsonian dolomite using a calcite and MgO standard and C by difference - because carbon coated

Result as follows
Sum 1
C 0.0968
O 0.5498
Mg 0.1339
Ca 0.2195

So too much Oxygen and not enough C, I'd like to try oxygen by stoichiometry and carbon by difference but only choice of one or other

Thanks

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