I PB X-ray and IR spectrometry Quantitative - - PowerPoint PPT Presentation

Quantitative Röntgenfluoreszenzanalyse Woran wir glauben und was wir wissen. Quantitative X-Ray Fluorescence Analysis

In what we believe and what we know.

Burkhard Beckhoff PTB Berlin, Germany

X-ray and IR spectrometry

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X-ray spectrometry methodologies: reference-based versus reference-free approaches

XRF excitation channel

reference material related technique reference-free technique based on well known calibration based on calibrated instrumen- specimens or reference materials tation and fundamental parameters

X-ray and IR spectrometry

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fluorescence radiation absolute detection efficiency and response functions unknown spectral distribution and / or unknown intensity fundamental parameters knowledge of the parameters d W F Y specimen d W F Y specimen unknown detection efficiency unknown response functions fluorescence radiation known spectral distribution and known intensity calibration specimens compensation for missing knowledge laboratory instruments well-known synchrotron radiation

Synchrotron radiation based x-ray spectrometry

fluorescence radiation d W absolute detection efficiency and response functions

solid angle well-known

well-known spectral distribution and a well-known radiant power F Y

XRF excitation channel XRF detection channel

XRS excitation channel: XRS detection channel:

specimen

fundamental parameters

knowledge of the parameters absorption correction factors

transmission measurements

 characterized beamlines  calibrated photodiodes  calibrated diaphragms  calibrated Si(Li) detectors

PTB capabilities:

X-ray and IR spectrometry

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JAAS 23, 845 (2008)

X-ray and IR spectrometry

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Quantitative XRF – primary excitation (Sherman equation)

 

0 E

Φ

in



• ut



t

dt

d

density line ce fluorescen

• f

y probabilit transition (sub)shell

• f

yield ce fluorescen section cross absorption electric

• photo

(sub)shell t coefficien absorption mass

s...

... ... ... ...

, , ,

  

line i shell i shell i s

f τ

             

                           W  d E E E E E f E Φ E Φ

• ut

i in

• ut

i in in shell i shell i line i d line i

             sin sin exp 1 sin sin 1 sin 1 4

, , , ,

instrumental parameters fundamental parameters

 

E Φd

i

• Phys. Rev. A 86, 042512 (2012)
• M. Kolbe

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 , E0 If substrate sample mi/F = mass deposition

Quantitative XRF – Sherman equation for thin layer samples

• R. Unterumsberger et al., Anal. Chem. 83, 8623 (2013)
• B. Beckhoff, J. Anal. At. Spectrom. 23, 845 (2008)

X-ray and IR spectrometry

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Quantitative XRF – Sherman equation for thin layer samples

• B. Beckhoff, J. Anal. At. Spectrom. 23, 845 (2008)

X-ray and IR spectrometry

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Quantitative XRF – Sherman equation for thin layer samples

• R. Unterumsberger et al.,
• Anal. Chem. 83, 8623 (2013)

Quantitative XRF – influence of the beam profile

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition I0, F‘0 I‘f substrate Assumption: F0 < F‘0 Consequence:

• 1. A: If < I‘f
• 1. B: If = I‘f
• 1. C: If > I‘f

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: I0 < I‘0 Consequence:

• 2. A: If < I‘f
• 2. B: If = I‘f
• 2. C: If > I‘f

I‘0, F0 I‘f substrate

Quantitative XRF – influence of the beam intensity

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: increase

• f sample thickness

Consequence:

• 3. A: If < I‘f
• 3. B: If = I‘f
• 3. C: If > I‘f

I0, F0 I‘f substrate

Quantitative XRF – influence of the sample thickness

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: increase

• f sample diameter

Consequence:

• 4. A: If < I‘f
• 4. B: If = I‘f
• 4. C: If > I‘f

I0, F0 I‘f substrate

Quantitative XRF – influence of the sample size

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: sample position influence Consequence:

• 5. A: If < I‘f
• 5. B: If = I‘f
• 5. C: If > I‘f

I0, F0 I‘f substrate

Quantitative XRF – influence of the sample position

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: more shallow incident angle Consequence:

• 6. A: If < I‘f
• 6. B: If = I‘f
• 6. C: If > I‘f

I0, F0 I‘f substrate

Quantitative XRF – influence of the incident angle

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 If substrate sample mi/F = mass deposition Assumption: more shallow observation angle Consequence:

• 7. A: If < I‘f
• 7. B: If = I‘f
• 7. C: If > I‘f

I0, F0 I‘f substrate

Quantitative XRF – influence of the angle of observation

Yes No

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 , E0 If substrate sample mi/F = mass deposition Assumption: E0 < E‘0 Consequence:

• 8. A: If < I‘f
• 8. B: If = I‘f
• 8. C: If > I‘f

I0, F0, E‘0 I‘f substrate

Quantitative XRF – influence of exciting photon energy

Yes No Note, that E0 > E K-abs, sample

X-ray and IR spectrometry

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E0 = photon energy of excitation radiation Ef = photon energy of fluorescence radiation I0 = intensity (photons/s) of excitation radiation If = intensity of fluorescence radiation in dW F0 = beam profile area (mm²) of excitation radiation dW = solid angle (sr) of fluorescence detection

I0, F0 , E0 If substrate sample mi/F = mass deposition

Quantitative XRF – influence of experimental parameters

• 1. A:
• 1. B:
• 1. C:

7 Yes No

• 2. A:
• 2. B:
• 2. C:
• 3. A:
• 3. B:
• 3. C:

Yes No

• 4. A:
• 4. B:
• 4. C:

Yes No

• 5. A:
• 5. B:
• 5. C:
• 6. A:
• 6. B:
• 6. C:

Yes No

• 7. A:
• 7. B:
• 7. C:

Yes No

• 8. A:
• 8. B:
• 8. C:

Yes No

7 5 2 9 7 4 3

10

8 4 4 6 5 9

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