Energy Dispersive X-Ray Fluorescence (ED-XRF)
Make: Thermo Fishers; Model – ARL Quant’ X
Principle: A secondary fluorescence photon is emitted by the sample, under the bombardment of primary photons emitted by the X-ray tube. The secondary photon enters the detector. It is converted to an electrical impulse. The height of this pulse is directly proportional to the energy of the incoming photon.
Accessories: Option to do analysis in vacuum and helium atmosphere.
Typical uses of EDXRF include the analysis of
X-ray Optics – 80o geometry between X-ray tube, sample and detector, distance from sample to PCD – 28.5 mm, X-ray tube target 54.1 mm.
X-ray tube – End window Bremsstrahlung, Rh target, 50 watt, 76 micrometer Be window, air cooled.
X-ray generator – Voltage range, 4 to 50 kV in 1 kV increments. Current range, 0-1.98 mA in 0.02 mA increments, Maximum 50 Watt output
X-ray stability – 0.25 % RSD over any 8 hour period
Filters: Automated 8 position filter selection, Al, Cellulose, 2 Cu and 3 Pd filters
Filter Collimators: 1mm and 8.8 mm
Chamber: Automated control of air, Vaccum, helium
Detector: Si (Li) 15 mm2 area, 155eV FWHM resolution for 5.9 keV X-ray at 1500 cps
Window: ≤ 7.6 mocron (0.3 mil) Beryllium (Be)
Cooling: Thermoelectric (Peltier ) and Air
Preamplifier: Electron resen
1. Elements determined: Sodium through Uranium
2. Concentration range: Parts per million to percent
3. Accuracy: Dependent on standards quality and concentration. Expected is 0.5 to 5.0 % relative
4. Precision: Dependent on concentration and analysis time. Expected is 0.5 to 5.0 %.
5. Calibration: Typically monthly
Samples Physical Properties:
Type: Solids, Powders, filtrates, liquids and thin films
Size: Standard single sample holds 1 ¼ inch (32 mm) dia sample cups or large, irregular samples up to the chamber size, i.e. 350 mm (W) x 450 (L) mm x 200 mm (H).
1. Non destructive analysis
2. Covers wide range from ppm to % level
3. It covers the periodic table from Na to U
4. Direct analysis of Solids and liquids.
1. Detection limits are poor for below ppm levels.
2. It won’t cover the light elements of periodic table.
3. To get homogeneous solid standards is difficult.