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ED-XRF: Principles and Applications
Justin Masone
Shimadzu Scientific Instruments
7 June 2016
AMC 2016 - UIUC
What is XRF?
• Analytical method to determine the elemental
composition of many types of materials
What is XRF?
• Analytical method to determine the elemental
composition of many types of materials
Fe 81.289%
Cr 17.0%
Mn 0.5%
Si 0.5%
Mo 0.3750
P 0.02%
440C
Stainless
What is XRF?
• Can be used to determine the thickness and
composition of layers, coatings, and platings.
Layer 1
15.156 μm
100% Cu
Base
100% Zn
What is XRF?
• Fast
• Accurate
• Non-destructive
What is XRF?
• Requires minimal sample prep
What is XRF?
• Sample form can be:
Powder Filter Paper
Solid Liquid
Types of XRF
First, some clarification…
X-Ray Fluorescence Spectrometry
Energy-Dispersive XRF
(EDXRF)
Wavelength-Dispersive XRF
(WDXRF)
Non-Dispersive XRF
(NDXRF)
What is ED-XRF?
Energy-Dispersive X-Ray Fluorescence
Energy-dispersive: Ability to discern the energies of x-rays
X-Ray: Form of energy; source of ionizing radiation
Fluorescence: Phenomenon of absorbing energy (short λ)
and subsequently emitting energy (longer λ)
Basis of EDX
Fluorescent
X-rays
1
2 3
4
5
6
Data Processing Unit
Pre-amp/DPP
Irradiating
X-rays
What are X-Rays?
X-rays are a kind of electromagnetic energy:
0.01 – 10 nm
0.125 – 125 keV
12 / 9
How Do X-Rays Interact with Matter?
When X-rays strike matter, some of them are absorbed and some
pass through
A consequence of absorption is that secondary X-rays are
generated, which are characteristic of that matter:
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How Do X-Rays Interact with Matter?
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How Do X-Rays Interact with Matter?
Degree of fluorescence
depends on:
• Thickness
• Density
• Sample material
X-ray penetration depth (Rh source):
Pb 25 μm
Fe 200 μm
H2O 3 cm Irradiating X-ray
Transmitted X-ray
ρd
Fluorescent X-ray
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How Do X-Rays Interact with Atoms?
++++++
-
-
-
-
- -
-
-
++
-
-
-
-
-
-Irradiating
X-ray
Ejected
Electron
Fluorescent
X-ray
16 / 9
Types of Transitions
Ratios of fluorescent X-rays:
Kα : Kβ = 100:20
Lα : Lβ = 100:70-100
These are “Characteristic X-rays”
17 / 9
Energy of X-Rays
X-rays exhibit wave-particle duality. The wave characteristics are
expressed in wavelength (λ, nm), and the particle characteristics are
expressed in the form of a photon with a specific energy (E, keV).
λ
E
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Energy of X-Rays: Example
++++++
-
-
-
-
- -
-
-
++-
Fe atom
Kα
=
(4.14 × 10−18𝑘𝑒𝑉 ∙ 𝑠) ×
(3.00 × 1017𝑛𝑚 ∙ 𝑠)
0.194 𝑛𝑚
19 / 9
Energy of X-Rays: Example
20 / 9
EDX Spectrum
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EDX Data Output
List of elements
present, including
carbon as a balance
Amount present in
sample; can be
reported in various
units Type of analysis
Transition used for
quantitative
calculation
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Analytical Range
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Types of X-Rays
Characteristic X-rays• Discrete energies
• Energy out
Continuous X-rays• Variety of energies
• Energy in
• “Background”
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Continuous X-Rays
In addition to fluorescence, an irradiating electron can be influenced by the attractive forces
of the nucleus and repulsive forces of the surrounding electrons without any actual collision.
In this case, the course of the electron is altered, which causes it to slow down and release
energy (an X-ray). This is called bremsstrahlung (braking radiation).
25 / 9
X-Ray Tube
X-ray tubes are <1% efficient
W
Rh over Cu
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EDX System
X-ray tube
Filters
Collimator
C-MOS
camera
Detector
(SDD)
Sample
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X-Ray Tube: Why Rhodium?
Why is rhodium used as the X-ray target?
• Rh K-rays are efficient at generating
fluorescent X-rays from heavy elements,
and the L-rays are efficient at generating
fluorescent X-rays from light elements
• Rh is rarely the subject of analysis
(however, Rh analysis is still possible)
28 / 9
X-Ray Tube: Scattered Radiation
Some of the X-rays from the tube do not generate fluorescent X-
rays when they strike the sample. Instead, they are scattered
within the sample. There are two types scattering radiation:
Compton Scattering: When the source characteristic X-rays (Rh) that strike the
material suffer from some energy loss (inelastic scattering)
Rayleigh Scattering: When the source characteristic X-rays (Rh) strike the sample
without any change in energy (elastic scattering)
29 / 9
X-Ray Tube: Scattered Radiation
Rayleigh
scattering
Compton
scattering
The intensity of the Compton scattering is
influenced by the material/density of the sample
30 / 9
X-Ray Tube: Scattered Radiation
• Samples with light elements give rise to high Compton scatter and low Rayleigh
scatter
• This is because they have more loosely bound electrons
• With very heavy elements, the Compton scattering disappears completely
Lead Plastic
31 / 9
Filters
We have learned that Rh X-rays contribute to the EDX spectrum, in terms of
characteristic X-rays, as well as continuous X-rays (background).
Sensitivity is low in these areas, so we introduce a filter to minimize the
source Rh and increase sensitivity:
32 / 9
Primary Filters
Filter #2 Filter #4 Filter #1
RhL line
Background from
continuous X-rays
RhK line
33 / 9
EDX Detector: SDD
Amptek XR-100FAST SDD is used in the EDX-7000/8000.
It is a High Performance Silicon Drift Detector.
X-rays from sample Be/C1 window ionize semiconductor material (high-purity
silicon) charge converted to voltage by FET (pre-amp) voltage converted to
digital count by DPP
34 / 9
EDX Detector: Si(Li) and Si-PIN
• Prior to high-performance SDDs, EDX utilized Si-PIN or Si(Li)
• These detectors are still common, but not in newer, “high end”
benchtop models
• High resolution• Must be LN2-cooled (-150 °C) to obtain
sufficiently low conductivity (e.g. best
resolution)
Si(Li)Si-PIN
• Moderate resolution and low count
rates (10 kcps), but is Peltier-cooled
35 / 9
EDX Detector: Si-PIN
• ~200 eV resolution (Mn-Ka)
• 32 μs peaking time
• P/B: 4000:1
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EDX Detector: SDD
• 125 eV resolution (Mn-Ka)
• 4 μs peaking time
• P/B: 22,000:1
37 / 9
Optional Hardware
Analysis can be done in air, He atmosphere, or under vacuum.
Atmospheric Control
Solid - Air, Vacuum, or Helium
Liquid - Air, Helium
Powder - Air, Vacuum*, Helium
For elements lighter than Cl, analysis must be done under atmospheric control O2
and CO2 in the atmosphere absorbs the fluorescent X-rays
Sensitivity will increase for light elements
38 / 9
Optional Hardware: Vacuum Pump
— Vacuum
— Air
-Na
Ka
-Mg
Ka
-AlK
a
-SK
a
-RhL
a
-RhL
b1
-KK
a
-Ca
Ka
-SiK
a
-Ca
Ka
39 / 9
Optional Hardware: Helium Purge
Helium Purge
Analysis is done in a helium atmosphere. The instrument purges the detector window
and X-ray tube window.
40 / 9
Example Applications
Electrical/electronic materials RoHS and halogen screening
Thin-film analysis for semiconductors, discs,
liquid crystals, and solar cells
Automobiles and machinery ELV hazardous element screening
Composition analysis, plating thickness
measurement, and chemical conversion
coating film weight measurement for
machine parts
Ferrous/non-ferrous metals Main component analysis and impurity
analysis of raw materials, alloys, solder, and
precious metals
Composition analysis of slag
Mining Grade analysis for mineral processing
Ceramics Analysis of ceramics, cement, glass, bricks,
and clay
Oil and petrochemicals Analysis of sulfur in oil Analysis of additive elements and mixed elements
in lubricating oil
Chemicals Analysis of products and organic/inorganic raw
materials Analysis of catalysts, pigments, paints, rubber, and
plastics
Environment Analysis of soil, effluent, combustion ash, filters,
and fine particulate matter
Pharmaceuticals Analysis of residual catalyst during synthesis Analysis of impurities and foreign matter in active
pharmaceutical ingredients
Agriculture and foods Analysis of soil, fertilizer, and plants Analysis of raw ingredients, control of added
elements, and analysis of foreign matter in foods
Others Composition analysis of archeological samples and
precious stones, analysis of toxic heavy metals in toys and everyday goods
41 / 9
Application Notes
Screening Analysis with EDX-7000 Navi Software
Quantitative Analysis of Elements in Small Quantity
of Organic Matter by EDXRF
- New Feature of Background FP Method -
Quantitative Analysis of Cement by EDX-8000
Quantitative Analysis of Waste Oil by EDX-7000
TC Measurement and Elemental Composition
Analysis of Fly Ash
- Quantitation by TOC and XRF -
Quantitative Analysis of Tin (Sn) in Plastics by
EDXRF
Analysis of Aqueous Solution by EDX-LE
- Performance in Air Atmosphere -
Quantitative Analysis of Fluorine (9F) by EDXRF
Quantitative Analysis of Antimony (Sb) in Plastics by
EDXRF
Qualitative and Quantitative Analysis of Seafood by
EDXRF
EDXRF Analysis of Arsenic and Lead in Dietary
Supplement
QC Analysis of Magnesium Alloy Die Castings by
EDXRF
EDXRF Analysis of PM2.5 (Particle Matter)
EDXRF Analysis of Sulfur and Other Elements in Oil
EDXRF Analysis of Lead, Cadmium, Silver, Copper in
Lead-Free Solder Materials
Determination of Arsenic and Lead in Earth and Sand
Using EDXRF [JIS K 0470]
Comparison of Calibration Curves of Lead, Cadmium
and Chromium in Zinc Alloy and Copper Alloy
EDXRF Analysis of Lead, Cadmium, Mercury and
Chromium in Zinc Alloy
EDXRF Analysis of Chlorine in Irregularly Shaped
Plastic Samples
Analysis of Foreign Matter in Food Using EDX
EDXRF Analysis of Heavy Elements in a Toy and a
Cup
EDXRF Analysis of Chlorine in Plastic (PE) Materials
Analysis of Sulfur in Oil Using Energy Dispersive X-
Ray Fluorescence Spectrometer
Analysis of Foreign Matter Using CCD
EDXRF Analysis of Arsenic in Foods
42 / 9
Quantitative Analysis Results for Foreign
Matter by FP Method
(Ti and Zn are excluded from the
quantitative calculations.)
Analysis Example: Foreign Matter Adhering to a Plastic Extruded Part
—F
e K
b
—N
i K
a
—C
r K
a
—C
r K
a M
n K
b
—T
i K
a
—T
i K
b
—N
i K
b
—Z
n K
a
—Z
n K
b
—M
o K
a
Foreign matter
Clean area
—F
e K
a
Sample
Appearance
Red circle: Foreign matter
Blue circle: Clean area
Application: Foreign Matter Identification
43 / 9
MRL Application: Film Thickness
Results from XRD: 26 nm
44 / 9
MRL Application: Brick from
Annealing Furnace
45 / 9
MRL Application: Carrot-Orange
Juice
01/01MTS-50C-60s-1-He Thermal-1-72C-15s-He Control-1-He MTS-60C-30s-2-He
Al-U
3.0 4.0
[keV]
0.00
0.50
1.00
1.50
2.00
[cps/uA]
S Ka
RhLa
RhLb1
K Ka
K Kb BaLa
Na-Sc
2.0
[keV]
0.00
0.50
1.00
1.50
2.00
[cps/uA]
RhLa ESC
RhLb1 ESC
P Ka
S Ka
RhLa
RhLb1
AgLa
AgLb1 K Ka
K Kb
46 / 9
MRL Application: Strontium
Contamination
• MRL XRD system was
unable differentiate
what seemed like
Strontium from other
peaks in the material
• Confirmation by EDX
allowed the user to
pursue this
contaminant.
47 / 9
MRL Application: Hafnium
Contamination
• Hafnium was unexpected, but the contaminant was tracked down to
the chamber in which the sample was made
48 / 9
Additional Information
Additional Information:
http://www.ssi.shimadzu.com
Tom Wilhite
Ray Kern