XRF and TXRF - Features and benefits
-
Upload
armin-gross -
Category
Technology
-
view
143 -
download
0
Transcript of XRF and TXRF - Features and benefits
The Benefits of TXRF for Ultra Trace Element Analysis
Innovation with Integrity
Dr. Armin GrossBruker Nano GmbH, Berlin, GermanyAugust, 2016
TXRF – How does it work?
3
Principles of EDXRFBackground
Energy-Dispersive X-Ray Fluorescence (EDXRF) analysis works in a 45°/45°geometry• Energy of X-ray photons
Which element• Number of X-ray photons
Quantitative analysis
4
Samples for common XRF spectrometry
• Solids (cut, polished and put into suitable shape)• Powders (as pressed pellets, fused beads
or loose powders in liquid cups)• Liquids (in liquid cups)
Necessary sample amount: from 1g to 10 g !!
Principles of EDXRFSamples
absorption of primary beamand fluorescence radiation
secondary fluorescenceenhancement
Ii = f (ci, cj) and ci = f (Ii, cj)
Concentration needs to be determinedwith matrix matched standardsDO YOU HAVE STANDARDS ???
Principles of EDXRFQuantification
5
6
Principles TXRF spectroscopyFunctional principle
X-ray tube
monochromator
detector
sample disc
Total reflection X-ray fluorescence spectroscopy
• Samples must be prepared on a reflective media• Polished quartz glass or polyacrylic glass disc • Dried to a thin layer, or as a thin film or microparticle
Beam angle: 0o / 90o
1. excitation spectrum2. spectrum after prefiltration,
filter component invisible here3. emission spectrum of the tube4. X-ray tube5. monochromator6. monochromatized excitation
beam7. detector8. sample carrier
4
3
2
1
5
8
7
6
7
Key to TXRF sensitivityHigh signal to low background
Monochromatization ofX-ray beam leads toalmost completereduction of background
8
Negligible absorption of primary beam and fluorescence radiation
Negligible secondary fluorescence enhancement
Ii = f ( ci ) ci = f ( Ii )
Samples are prepared as thin films or layersmatrix effects are negligible
Principles TXRF spectroscopyMatrix effects
9
iIS
ISiISi SN
SNCC
Ci: Element concentrationCIS: Internal standard concentrationNi: Element net countrateNIS: Internal standard net countrateSi: Element sensitivity factorSIS: Internal standard sensitivity factor
Element sensitivity
L-linesK-lines
Atomic number
Principles of TXRFQuantification
Lack of matrix effect allowseasy quantification by internal standardization
10
Samples for TXRF• Powders: Direct preparation
or as suspension• Liquids: Direct preparation• Always as a thin film, micro fragment or
suspension of a powder• Necessary sample amount:
Low µg respectively µl range
Principles TXRFSamples
TXRF SpectrometerS2 PICOFOX
S2 PICOFOX – Compact TXRF
11
• Most compact design portable, for on-site analysis
• Fixed excitation mode easy to use, mostsuitable for teaching
• >200 installations well established world wide technology
• Attractive pricing most valuable TXRFsolution
TXRF SpectrometerS4 TStar
S4 TStar – Advanced TXRF
12
• Multiple excitation to detect most elements modes of the PSE
• Large area detectors improved sensitivity for lowest limits of detection
• Sample geometry measurement of discs, flexibility microscopy slides, wafers
• Motorized beam path automatic beam adjustment and QC procedures
• Large sample capacity up to 90 sample discs, multi-user operation
Rigaku Nanohunter II
• Benchtop model
• Mo X-ray tube, 600 W
• 16 samples capacity
GNR TX 2000• Floor-standing model
• Mo, W double target tube, 3 kW
• 12 samples capacity
13
TXRF SpectrometerOther systems
Straight forward sample preparation
quartz glass glass carbon sapphire acrylic glass
15
acrylic glass
quartz sapphire
glass carbon
Sample carrier
Quartz glass carriersdeliver lowest detectionlimits due to lowbackground
fill sample in micro tube
add internal standard
homogenize
Note: high matrix samples pipette on carriermay require a dilution step
You‘ll need just a few steps for the preparation of liquid samples
16
Sample preparationLiquid and digested samples
dry by heat / vacuum
load the instrument
start data aquisition
17
Sample preparationFinal steps
dilute sample with distilled water
add internal standard
homogenize
pipette on carrier
Suspensions can be analyzed just after dilution
18
Sample preparationSuspensions
fill powder in mortar
grind carefully (<50 µm)
weigh about 20-50 mg
transfer to tube
Solids are ground to fine particle size and resuspended for direct analysis without digestion
19
Sample preparationSolid and powder samples I
suspend in detergent solution
add standard
homogenize
pipette on carrier
20
Sample preparationSolid and powder samples II
Sample preparationMicroparticles
dab vacuum grease on carrier
pick-up some particles with a (glass) rod
drop particles on grease
Microparticles are measured semi-quantitatively and non-destructively
21
Current application areasTime for you to start with TXRF
Environmental /Ecology
Clinical Research / Biology Forensics Semiconductor
Nanoparticles Food/BeveragePharmaceutical/
Nutraceutical Plant Research
22
www.facebook.com/groups/TXRFSpectrometry
eu.wiley.com/WileyCDA/WileyTitle/productCd-1118460278.html
www.s4tstar.com
www.s2picofox.com
23
TXRFMore information required?