XRF Analysers: Principles, Applications and Advantages

Abstract: This paper elaborates on the working principle of XRF analysers (Energy Dispersive X-Ray Fluorescence Spectrometers), which involves analyzing the wavelength and intensity of characteristic X-rays emitted by test samples. It determines the elements contained in the sample based on the differences in the wavelength of characteristic X-rays of different elements, and measures the elemental content in the sample by comparing the intensity of spectral lines of different elements. Taking the LISUN EDX-2A XRF Analyser as an example, this paper introduces its product features, specifications, as well as applications in RoHS testing, elemental analysis, and coating thickness measurement. It also discusses the advantages and characteristics of this instrument in various application fields, demonstrating the important position and broad application prospects of XRF analysers in modern analytical testing.

1. Introduction​
In numerous fields such as material analysis, environmental monitoring, and food safety, accurate determination of the types and contents of elements in substances is of crucial importance. XRF analysers (Energy Dispersive X-Ray Fluorescence Spectrometers), as advanced analytical instruments, have become powerful tools for elemental analysis due to their unique working principles and excellent performance. They can conduct rapid, accurate, and non-destructive elemental analysis on various samples, providing key data support for scientific research, production, and quality control. This paper will deeply explore the principles, applications, and advantages of XRF analysers, with detailed elaboration based on the specific conditions of the LISUN EDX-2A XRF Analyser.​

2. Working Principle of XRF Analysers​
2.1 Basic Principle​
When a sample is irradiated by high-intensity X-rays emitted from an X-ray tube, atoms of elements in the sample absorb a certain amount of energy, causing electrons within the atoms to transition from low energy levels to high energy levels, forming excited atoms. Excited atoms are unstable and will spontaneously transition back from high energy levels to low energy levels within an extremely short time (approximately 10⁻¹² – 10⁻¹⁴ seconds), a process known as the relaxation process. During the relaxation process, if outer electrons transition to inner electron holes, the released energy is emitted in the form of radiation, generating X-ray fluorescence. Due to the differences in atomic structures of different elements, their energy level differences also vary. Therefore, the energy or wavelength of the generated X-ray fluorescence is characteristic, showing a one-to-one correspondence with elements. For example, after a K-shell electron is ejected, its hole can be filled by any electron in the outer shell, generating a series of spectral lines. The X-ray radiated when an L-shell electron transitions to the K-shell is called a Kα ray, and the X-ray radiated when an M-shell electron transitions to the K-shell is called a Kβ ray, etc. H.G. Moseley discovered that the wavelength λ of fluorescent X-rays and the atomic number Z of elements satisfy Moseley’s Law: λ = K (Z – s)⁻², where K and S are constants. As long as the wavelength of fluorescent X-rays is measured, the type of element can be determined, which serves as the basis for qualitative analysis of fluorescent X-rays.​

Meanwhile, the intensity of fluorescent X-rays has a certain relationship with the content of the corresponding element. In a sample containing a certain element, when irradiated by X-rays once, the intensity of the fluorescent X-rays of that element changes with its content—the higher the element content, the stronger the intensity of the fluorescent X-rays. By pre-measuring the intensity of fluorescent X-rays of samples with known concentrations and establishing a corresponding relationship between intensity and concentration, the content of the element in unknown samples can be deduced, which provides the possibility for quantitative analysis of elements.​

2.2 Instrument Working Process​
XRF analysers use a fixed energy-dispersive semiconductor detector to simultaneously measure the specific signals of all elements. When characteristic X-ray photons enter a lithium-drifted silicon detector (a commonly used EDX detector), they ionize silicon atoms, generating a number of electron-hole pairs, the quantity of which is proportional to the energy of the photons. A bias voltage is used to collect these electron-hole pairs, which are then converted into voltage pulses through a series of converters and supplied to a multi-pulse height analyzer. The analyzer counts the number of pulses in each energy band of the energy spectrum. The measured spectrum is processed in a multi-channel analyzer to determine the spectral signal intensity, and the signal radiation intensity of each element is proportional to the concentration of that element in the sample. Finally, the signal is used to calculate the concentration of elements in the sample using methods such as the empirical calibration method. The entire process can be summarized as follows: X-rays excite the sample to generate fluorescent X-rays, the detector receives and converts the signals, and the multi-channel analyzer processes the signals and calculates the elemental concentration.​

3. Introduction to LISUN EDX-2A XRF Analyser​
3.1 Product Overview​
The LISUN EDX-2A XRF Analyser is a high-performance analytical instrument that has been on the market for more than 10 years and has gained a good reputation. The EDX-2 series, to which this instrument belongs, has multiple functions—a single machine can simultaneously act as a RoHS tester (EDXRF), a metal elemental analyzer, and a coating thickness gauge.​

3.2 Specifications​
The main specifications of the LISUN EDX-2A XRF Analyser are shown in the table below:

Specification	EDX-2A	EDX-2AC	EDX-2AB	EDX-2ABC	EDX-2T
Type	Non -pumping air desktop				Vacuum desktop
Weight	50KG				55KG
Test time	200S				100S
Sample cavity size	610*320*100mm (L*W*H)				510*310*120mm（Non -vacuum）
					Ф100*70mm（vacuum）
Test environment	atmosphere				Vacuum
Detector	Si-pin				SDD
Resolution	149 Electronic Volt				129 Electronic Volt
Output tube pressure, current	50KV/600uA（Can automatically set）				50KV/600uA（Can automatically set）
Test sample type	Solid, liquid, powder				Non -vacuum: solid, liquid, powder
					Pumping vacuum: solid
Content analysis range	2ppm–99.99%				2ppm–99.99%
Test items	Typic Application 1：RoHS	Typic Application 1：RoHS	Typic Application 1：RoHS	Typic Application 1：RoHS	Typic Application 1：RoHS
		Typic Application 3: Coating and Plating Thickness	Typical application 2: alloy analysis	Typical application 2: alloy analysis	Typical application 2: alloy analysis
				Typic Application 3: Coating and Plating Thickness	Typic Application 3: Coating and Plating Thickness
Metal test element range	Can not test		All elements in the Periodic Table of Elements from 16-S to 92-U  are available for alloy analysis (iron, copper, stainless steel, Au (gold), Pt (platinum) , etc)		All elements in the Periodic Table of Elements from 11-Na to 92-U are available for alloy analysis (magnesium aluminum alloy, ore component, iron, copper, stainless steel, Au (gold), Pt (platinum) , etc)

4. Application Fields of XRF Analysers​
4.1 RoHS Testing​
In the electronic and electrical industry, the RoHS directive imposes strict restrictions on the content of hazardous substances such as lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), and bromine (Br) in products. XRF analysers, such as multiple models in the LISUN EDX-2A series (EDX-2A, EDX-2AB, EDX-2AC, EDX-2ABC, EDX-2T), can be used for RoHS 1.0 testing of electronic and electrical products, components, plastics, and plastic parts. Through rapid and non-destructive testing of samples, they can accurately determine whether the content of hazardous substances in products meets the requirements of the RoHS directive, providing an important basis for enterprise product quality control and market access. For example, in an electronic component manufacturing enterprise, the LISUN EDX-2A XRF Analyser is used to conduct RoHS testing on raw materials and finished products. This enables the timely detection and elimination of products that may have excessive hazardous substances, effectively avoiding the risk of market recalls caused by non-compliant products.​

4.2 Elemental Analysis​
Alloy Analysis: In industries such as metal processing and machinery manufacturing, accurate analysis of alloy compositions is required to ensure product quality and performance. XRF analysers of models such as LISUN EDX-2AB, EDX-2ABC, and EDX-2T can conduct alloy analysis on all elements from sulfur (16-S) to uranium (92-U) in the periodic table (some models can cover elements from sodium (11-Na) to uranium (92-U)), including iron, copper, stainless steel, gold, platinum, etc. By analyzing the content of each element in the alloy, the alloy grade can be determined, and its quality can be evaluated to see if it meets standard requirements. For example, during steel production, XRF analysers are used for real-time elemental analysis of molten steel in the furnace. Based on the analysis results, the addition amount of alloying elements is adjusted in a timely manner to ensure the quality stability of the steel.​
Precious Metal Analysis: In the jewelry industry, accurate determination of the purity and content of precious metals (such as gold, silver, platinum, etc.) is crucial. XRF analysers can conduct non-destructive testing on precious metal jewelry, quickly providing information on the content of various elements, helping merchants and consumers identify the authenticity and purity of precious metals. For example, a jewelry appraisal institution uses an XRF analyser to test a batch of gold jewelry. By analyzing the content of gold and other impurity elements in the jewelry, it accurately determines the purity level of the jewelry, providing a fair and accurate appraisal result for market transactions.​

Other Elemental Analysis: In industries such as petrochemicals, pharmaceuticals, and food, XRF analysers can also be used to analyze various elements in raw materials and products. In the petrochemical industry, they can analyze the sulfur content in oil and the content of various additive elements and mixed elements in lubricating oil. In the pharmaceutical field, they can be used for residual catalyst analysis during synthesis, impurity analysis in bulk drugs, and foreign matter analysis. In the food industry, they can conduct elemental analysis on soil, fertilizers, plants, and food raw materials to monitor additive element management and dissolved foreign matters. For example, in a food production enterprise, XRF analysers are used to test heavy metal elements in food raw materials to ensure food safety and prevent harm to consumers’ health caused by excessive heavy metals in raw materials.​

4.3 Coating Thickness Measurement​
In industries such as electronics, automobiles, and machinery, it is often necessary to accurately measure the thickness of coatings on product surfaces to ensure the protective performance and appearance quality of the products. XRF analysers of models such as LISUN EDX-2AC, EDX-2ABC, and EDX-2T have the function of coating thickness measurement. They can analyze the elements in the coating and calculate the coating thickness through specific algorithms. For example, in the electroplating process of electronic device casings, XRF analysers are used to monitor the coating thickness in real-time, ensuring that the coating thickness is uniform and meets the design requirements, thereby improving the corrosion resistance and aesthetics of the product.​

5. Advantages of XRF Analysers​
5.1 Rapid Analysis​
XRF analysers can simultaneously determine almost all elements in a sample, without the need to test elements one by one like traditional analytical methods. For example, when analyzing a complex alloy sample, traditional chemical analysis methods may take hours or even days to complete the determination of multiple elements, while XRF analysers can complete the qualitative and quantitative analysis of multiple elements in the sample within a few minutes. This greatly shortens the analysis time and improves work efficiency.​

5.2 Non-Destructive Testing​
This instrument does not cause damage to the sample during the analysis process, which is particularly important for application scenarios involving precious samples, cultural relics, or samples with strict requirements for integrity. For example, in archaeology, when conducting elemental analysis on ancient cultural relics, XRF analysers can obtain information on the elemental composition of the cultural relics without damaging them, providing important clues for studying the manufacturing process and origin of the cultural relics.​

5.3 Simultaneous Multi-Element Detection​
They can detect multiple elements in a sample simultaneously, avoiding errors that may occur due to repeated testing of different elements, and enabling comprehensive analysis of the interrelationships between elements. In environmental monitoring, when testing soil samples, XRF analysers can simultaneously detect heavy metal elements (such as lead, cadmium, mercury, etc.) and nutrient elements (such as nitrogen, phosphorus, potassium, etc.) in the soil, providing rich data for a comprehensive evaluation of soil quality.​

5.4 Easy Operation​
The instrument is equipped with an automated control testing system and user-friendly analysis software. Operators can master the operation method of the instrument proficiently after simple training. Compared with some traditional analytical instruments, such as large spectrometers that require complex operations and professional knowledge, XRF analysers reduce the professional requirements for operators, allowing more laboratories and enterprises to easily carry out elemental analysis work.​

5.5 Wide Application Range​
They can analyze various types of samples such as solids, liquids, and powders. Whether it is the research of new materials in the scientific research field, the quality control of raw materials and products in industrial production, or the testing of different samples in fields such as environmental monitoring and food safety, XRF analysers can play an important role.​

6. Conclusion​
XRF analysers demonstrate powerful functions and advantages in the field of elemental analysis relying on their unique working principles. Represented by the LISUN EDX-2A XRF Analyser, XRF analyser products not only have the characteristics of high resolution, easy operation, and safety reliability but also play a key role in multiple application fields such as RoHS testing, elemental analysis, and coating thickness measurement. With the continuous advancement of science and technology, the performance of XRF analysers will continue to improve, and their application scope will be further expanded. They will provide more powerful support for the development of numerous fields such as materials science, environmental science, and life science, and occupy an increasingly important position in modern analytical testing.

Tags：EDX-2A