Getting the concentration from Scanning Electron Microscope

In summary, to obtain the concentration of an element in ppm, you can use the percent element values provided in the output and multiply by 10,000. The fields in the EDX output refer to various correction factors applied to the apparent concentration of the element.
  • #1
schrodingerscat11
89
1
Greetings!

I am doing particle analysis using a JEOL 5310 Scanning Electron Microscope (SEM). Typically, people here in the lab report the results in % Element or % Atomic. I think the former refers to the weight percentage of an element and the latter to the stoichiometric ratio of elements with each other. Anyway, is there a way to get the concentration of the element of the particle in terms of ppm (parts per million)?

Also, what to the fields in the EDX output mean? The Apparent conc., stat. sigma, k ratio, k ratio sigma, Inten. Corrn., Std. Corrn.?

Here is an example output of an Energy Dispersive X-ray (EDX) analysis:
===================================================================
SEMQuant results. Listed at 6:37:31 PM on 10/3/12
Operator: Oxford
Client: All ISIS users
Job: Demonstration data SiLi detector
Spectrum label:

Calibration data: Energy Resn. Area
Strobe: -8.8 49.21 90606
Calib. element: 6915.1 140.83 37196
Gain factor = 49.989
Livetime = 100.0 seconds

Sample data: Energy Resn. Area
Strobe: -7.4 53.64 54030
Total spectrum counts = 5342
Livetime = 56.2 seconds

System resolution = 70 eV

Geometry (degrees):
Tilt = 0.00

ED geometry (degrees):
Elevation = 45.00
Azimuth = 0.00
Entry angle = 0.00

Accelerating voltage = 20.00 kV

Quantitative method: ZAF ( 4 iterations).
Analysed all elements and normalised results.

Standards :
C K CaCO3 01/12/93
Cl K KCl 15/02/94
Ca K Wollas 23/11/93
V K V 01/12/93
Co K Co 01/12/93
Br K KBr 07/12/93
Zr L Zr 01/12/93
Au M Au 01/12/93
Hg M HgTe 01/12/93


Elmt Spect. Apparent Stat. k Ratio k Ratio
Type Conc. Sigma Sigma

C K ED 12.754 0.297 1.06280 0.02478
Cl K ED 0.040* 0.032 0.00084* 0.00067
Ca K ED 0.068* 0.044 0.00199* 0.00129
V K ED 0.006* 0.048 0.00006* 0.00048
Co K ED 0.030* 0.074 0.00030* 0.00074
Br K ED 0.060* 0.461 0.00089* 0.00687
Zr L ED 0.113* 0.150 0.00113* 0.00150
Au M ED 2.021 0.177 0.02021 0.00177
Hg M ED 0.128* 0.226 0.00210* 0.00370

Elmt Spect. Inten. Std Element Sigma Atomic
Type Corrn. Corrn. % % %

C K ED 1.093 1.46 80.20 3.66 98.10
Cl K ED 0.847 1.02 0.33* 0.26 0.13*
Ca K ED 1.028 1.00 0.46* 0.29 0.17*
V K ED 0.872 1.00 0.05* 0.38 0.01*
Co K ED 0.880 1.00 0.23* 0.58 0.06*
Br K ED 0.853 1.00 0.48* 3.70 0.09*
Zr L ED 0.895 1.05 0.87* 1.14 0.14*
Au M ED 0.844 1.05 16.44 1.43 1.23
Hg M ED 0.929 1.05 0.95* 1.65 0.07*
Total 100.00 100.00

* = <2 Sigma

===================================================================


Thank you very much for your help.
 
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  • #2
To calculate the concentration of an element in parts per million (ppm), you will need to use the percent element values given in the output. Multiply the percent by 10,000 to obtain the concentration in ppm. For example, for the element C, its concentration is 12.754% so its concentration in ppm is 127,540 ppm. The fields in the EDX output refer to the following:Apparent Conc. - The apparent concentration of the element in the sample.Stat. Sigma - The standard deviation of the apparent concentration.k Ratio - The correction factor applied to the apparent concentration to obtain the corrected concentration.k Ratio Sigma - The standard deviation of the k ratio.Inten. Corrn. - The intensity correction factor applied to the apparent concentration.Std. Corrn. - The standard correction factor applied to the apparent concentration.
 

1. How is the concentration obtained from a Scanning Electron Microscope?

The concentration can be obtained from a Scanning Electron Microscope by measuring the intensity of the electron beam as it interacts with the sample. The more intense the beam, the higher the concentration of the element being analyzed.

2. Can the concentration be measured for all elements using a Scanning Electron Microscope?

Yes, a Scanning Electron Microscope can measure the concentration of all elements, as long as they are present in the sample being analyzed. However, the accuracy and sensitivity may vary depending on the element's atomic number and the composition of the sample.

3. Is the concentration measured in absolute or relative terms with a Scanning Electron Microscope?

The concentration is measured in relative terms with a Scanning Electron Microscope. This means that the instrument provides a comparison of the concentration of the element in the sample relative to the concentration of other elements present in the sample.

4. How long does it take to get the concentration from a Scanning Electron Microscope?

The time it takes to obtain the concentration from a Scanning Electron Microscope varies depending on the type of sample, the elements being analyzed, and the instrument's settings. However, it typically takes a few minutes to get accurate results.

5. What factors can affect the accuracy of the concentration measurements from a Scanning Electron Microscope?

There are several factors that can affect the accuracy of concentration measurements from a Scanning Electron Microscope, such as the sample preparation technique, the instrument's calibration, and the presence of other elements or contaminants in the sample. Additionally, the operator's skill and experience can also influence the accuracy of the measurements.

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