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MAN versus Off-peak Background Measurements

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Presentation on theme: "MAN versus Off-peak Background Measurements"— Presentation transcript:

1 MAN versus Off-peak Background Measurements
What Is It Good For? Saving TIME!

2 How Much Time? 186 seconds w/ Off-Peaks 94 seconds w/ MAN

3 What Else is it Good For? Avoiding Off-Peak Interferences
Spectrometer Reproducibility Issues Sensitive Samples Quantitative Imaging Avoiding Wear and Tear on Spectrometers

4 Avoiding Off-Peak Interferences
By not measuring off-peak intensities in samples of unknown composition, one can eliminate even unforseen off-peak interferences.

5 Spectrometer Reproducibility Issues
Ultra High Precision Measurements Handle spectrometer re-positioning problems By reserving a spectrometer for a single MAN corrected element x-ray line (monochromator), one can obtain:

6 Na/K Loss in glass (or Si/Al “grow-in”)
Sensitive Samples Na/K Loss in glass (or Si/Al “grow-in”) Everyone knows about sodium loss over time in some glasses and especially, hydrous phases- but did you know that sodium can also “grow-in”?

7 Sodium Calcium Silicate (cement “gel”)

8 (512 x 2048 pixels @ .5 sec equals 6 days!)
Quantitative Imaging Eliminate acquisition time for off-peak intensity images and still obtain background corrected quantitative images (512 x sec equals 6 days!)

9 How Good Is It? Major Elements Minor Elements Trace Elements
Comparison to Off-Peak Measurements Matrix Issues (Low Z-bar vs High Z-bar) Accuracy (reproducibility, drift, etc)

10 Comparison with Off-peak
20 kev, 20 nA, 5 um, 20 sec on, 20 sec off St 305 Set 2 Labradorite (Lake Co.) ELEM: Ca K Fe Ti Na Al Mn Ni O H Si SUM AVER: SDEV: %RSD: PUBL: n.a n.a n.a %VAR: DIFF: STDS: PKBG: MAN St 305 Set 2 Labradorite (Lake Co.) ELEM: Ca K Fe Ti Na Al Mn Ni O H Si SUM AVER: SDEV: %RSD: PUBL: n.a n.a n.a %VAR: DIFF: STDS: PKBG:

11 High Z-bar Off Peak Comparison
20 kev, 20 nA, 5 um, 20 sec on, 20 sec off St 396 Set 2 Chromite (UC # 523-9) ELEM: Ca K Fe Ti Na Al Mn Ni O H Cr SUM AVER: SDEV: %RSD: PUBL: n.a. n.a n.a n.a n.a %VAR: DIFF: STDS: PKBG: MAN St 396 Set 2 Chromite (UC # 523-9) ELEM: Ca K Fe Ti Na Al Mn Ni O H Cr SUM AVER: SDEV: %RSD: PUBL: n.a. n.a n.a n.a n.a %VAR: DIFF: STDS: PKBG:

12 Drift Issues in MAN Drift array background intensities for standards:
ELMXRY: ca ka k ka fe ka ti ka na ka al ka mn ka ni ka MOTCRS: 2 PET 2 PET 4 LIF 3 LIF 1 TAP 1 TAP 3 LIF 4 LIF STDASS: Drift array standard intensities (background corrected):

13 Typical Sequence of MAN Fit

14 Cr K-b interference removed

15 Trace Ni “contamination” removed (natural chromite, 0.087 wt. % Ni)


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