X-Ray Fluorescence (XRF)

Principles of X-Ray Fluorescence (XRF) Spectrometry

In XRF spectrometers, X-rays are produced by a source and aimed at the sample. In most cases, the source is an X-Ray Tube, but sometimes a Synchrotron or a radioactive material is used. Elements in the sample, when struck by this radiation, emit fluorescent X-rays with discrete energies (similar to light) that are characteristic and unique to each element.

The emitted energies are equivalent to different colors. By measuring the energy emitted from the sample (measuring the "color"), we can determine which elements are present in the sample. This stage is referred to as Qualitative Analysis. Next, by measuring the intensity of the emitted energy (the "color intensity"), we can determine the amount of each element in the sample. This stage is referred to as Quantitative Analysis.

Types of XRF Instruments

XRF instruments are divided into two main types: Benchtop and Portable (Handheld). The benchtop model typically offers higher accuracy and is suitable for a laboratory setting, while the portable model has lower accuracy and is better suited for field research and mineral exploration.

Applications of XRF Instruments

The XRF instrument has a wide range of applications, including the following:

• Soil and Earth Analysis: Determining soil quality, assessing the industrial value of soil, and environmental control.

• Mining Industry: Analyzing incoming raw materials, controlling waste streams, and monitoring intermediate and final output products.

• Chemicals and Energy.

• Cement Industry: Controlling the elemental composition of raw materials, intermediate products, and final products.

• Ceramics Manufacturing: Quality control in production.

• Glass Manufacturing.

• Materials Metallurgy: Qualitative and quantitative control of elements in alloys and raw materials.

• Steel Industry: Quality control of purchased scrap iron.

• Environmental Research: Monitoring waste and environmental quality.

• Pharmaceuticals: Quality control of raw materials and manufacturing processes.

• Field Research in various areas, including geology: Determining the quality of mineral ores and other similar applications.

Main Components and Operational Schematic

• X-Ray Source

• Sample Holder

• Collimator

• Analyzing Crystal

• Detector

Advantages

• The fastest analyzer globally (High throughput of over 400,000 measurements per second (CPS)), offering the highest accuracy and shortest measurement time.

• Wide detection range of elements from Sodium (Na, Z=11) to Uranium (U, Z=92).

• Modern spectrometers utilize helium environments to lower the analysis detection limit and improve the accuracy of analyzing lighter elements (such as Na, Mg, Al, Si, P, S).

• Long-term calibration stability and the ability to compensate for environmental temperature and pressure changes.

• Automatic sample changer and increased productivity.

• Use of high-resolution CCD cameras for precise sample positioning.

• Easy sample preparation and low maintenance costs.

• Low analysis cost.

Disadvantages

• Limitations in accurately measuring elements with an atomic number less than 11.

• Limited ability to distinguish between different isotopes of a single element.

• Limited ability to differentiate between various ions of a single element.

Summary

The XRF instrument is a practical tool for the quantitative and qualitative measurement of chemical elements. Given the variety of products and wide measurement ranges, it has broad applications across many industries. Due to its high analysis speed and low maintenance cost, it's a suitable replacement for traditional laboratory methods.