The Composition of An XRF
X-ray Fluorescence (XRF) spectrometers are non-destructive elemental analysis instruments that use high-energy X-rays to irradiate a sample, exciting the atoms within it to produce characteristic X-rays. These characteristic X-rays are then used to analyze the elemental composition and concentration within the sample. XRF spectrometers are widely used in fields such as geological exploration, metal smelting, industrial product inspection, environmental monitoring, and archaeological artifact identification.
Modern XRF spectrometers, whether benchtop or handheld, typically include the following four main components:
1. X-ray Tube
The X-ray tube is the core component of the XRF spectrometer, responsible for generating high-energy X-rays. The working principle of the X-ray tube involves accelerating electrons at high voltages to strike an anode target, such as rhodium (Rh), silver (Ag), chromium (Cr), molybdenum (Mo), or tungsten (W). This collision knocks out inner-shell electrons, creating vacancies. To fill these vacancies, outer-shell electrons transition to inner shells, releasing energy in the form of X-rays.
The performance of the X-ray tube significantly impacts the analytical precision and sensitivity of the XRF spectrometer. Common types of X-ray tubes include:
- End-window X-ray tubes: Simple structure and lower cost but weaker X-ray intensity.
- Side-window X-ray tubes: Higher X-ray intensity but more susceptible to contamination.
- Zero-window X-ray tubes: High X-ray intensity and less prone to contamination but higher cost.
2. Sample Loading Device
The sample loading device is responsible for positioning the sample for X-ray irradiation and detection. The design of the sample loading device must consider the size, shape, and state of the sample.
- Handheld XRF spectrometers: Typically use direct detection methods, with light shields around the emission source to prevent interference. Samples are usually placed directly on the probe window for analysis.
- Benchtop XRF spectrometers: Samples are placed on a sample stage for analysis. The sample stage can offer various sample fixation methods and adjust the distance between the sample, the X-ray tube, and the detector.
3. X-ray Detector
The X-ray detector is responsible for detecting the characteristic X-rays emitted by the sample and converting them into electrical signals. The performance of the X-ray detector significantly impacts the analytical precision and sensitivity of the XRF spectrometer.
Common types of X-ray detectors include:
- Gas-filled proportional counters: Work by using the interaction of X-rays with gas atoms to produce ionization, and collecting the charges in an ionization chamber.
- Solid-state detectors: Work by using the interaction of X-rays with semiconductor materials to produce charge carriers, and collecting the charges with electrodes.
Solid-state detectors are increasingly popular due to their small size, lightweight, high resolution, and high sensitivity.
4. Data Processing System
The data processing system collects, analyzes, and processes the electrical signals output by the X-ray detector, converting them into elemental concentration or content data. The data processing system typically includes:
- Multi-channel Analyzer (MCA): Measures pulse amplitude and processes the signal into an X-ray energy spectrum.
- Spectrum Analysis Software: Analyzes the X-ray energy spectrum and calculates the concentration or content of elements in the sample.
- Display and Storage Devices: Display and store the analysis data.
The performance of the data processing system significantly impacts the analytical efficiency and reliability of the XRF spectrometer.
Additional Components
In addition to the four main components mentioned above, XRF spectrometers may also include auxiliary components such as vacuum systems, cooling systems, and power supplies. These auxiliary components also influence the performance of the XRF spectrometer.
What Kind of X-Ray Tubes Are Availabel For XRF?
An X-ray tube is a device capable of producing X-rays. The XRF fluorescence spectrometer uses the strong penetrating ability of X-rays to illuminate the surface of the object to be tested and excite fluorescence to detect the types of elements contained in the object to be tested.
X-ray tube is an indispensable main component and the main consumable in XRF instrument. If you plan to purchase an XRF fluorescence spectrometer for your experiment, you must know something about X-ray tubes.
How A XRF Analyze The Elements?
Atomic electron can be ejected out of the original orbital by absorbing the X-ray energy, and this energy must be greater than the energy that the electron is bound to the nucleus of the original orbital. When this inner-shell electron is ejected out of the orbital, one another electron in the outer shell, with higher energy, will fill out this empty position, and the release the energy in the form of photons (fluorescence), and the energy is exactly equal to the energy difference between the two neighborhood shells.
Such kind of fluorescence that is generated by the electronic transitions, is so called characteristic X-ray of the element. Since the energy dissipation between two adjacent orbitals is always a constant, by measuring the amount of fluorescence can identify a particular element. It is the principle of the X-ray Fluorescence Spectroscopy (XRF). And the spectrometer is designed.
Principle of XRF
Furthermore, a particular fluorescence of an element, of which the number of photons per time unit is related to the materials in the sample. Typically, X-ray Fluorescence Spectroscopy (XRF) represent the value by a peak intensity or count rate. This result will be presented in the characteristic X-ray lines from the spectrometer. Each element has its peak value belongs; and these fluorescent spectrum lines will appears in the shape of the semi-Gaussian distribution, because the count of the resolution of the modern detectors are still not perfect .
Therefore, the observation of these peaks, and the number of the peaks of elements, we can have the composition of elements in the material. Besides, by quantitatively measurement, one can analyze the concentration of samples and have better understanding on the composition of the entire sample by a spectrometer.
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What Is An XRF Spectrometer?
XRF is the abbreviation of “X-ray Fluorescence”. An XRF Spectrometer is an x-ray instrument used for routine, relatively non-destructive chemical analyses of rocks, minerals, sediments and fluids. It works on wavelength-dispersive spectroscopic principles that are similar to an electron microprobe (EPMA).
However, an XRF cannot generally make analyses at the small spot sizes typical of EPMA work (2-5 microns), so it is typically used for bulk analyses of larger fractions of geological materials. The relative ease and low cost of sample preparation, and the stability and ease of use of x-ray fluorescence spectrometers make this equipment one of the most widely used methods for analysis of major and trace elements in rocks, minerals, and sediment.
ACTTR is the most aggressive & the most professional instrument of spectrometer distributor, agent, reseller, in Taiwan.
Does TXRF Require Cumbersome Calibration Process?
Strictly speaking, TXRF does not require Calibration. GNR's TX 2000 TXRF spectrometer is delivered with factory calibration, via precise instrument calibration process. In the day-to-day routine analysis, TXRF quantify the unknown substance by incerting the internal sandard into the sample solution. The common internal standard in TXRF measurement is gallium.
In other words, the general drift error in TXRF won't affect the measurement result.
ACTTR Technology represents the assurance grade gallium standard, PLGA2-2Y, which is a 125ml packaging. It is a necessary product for TXRF.