Energy-dispersive X-ray spectroscopy

Energy-dispersive X-ray spectroscopy (EDX or EDS) is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on the interaction between X-rays and matter to identify and quantify the elemental composition of a sample. This method is a key tool in the field of materials science, forensic science, geology, and semiconductor analysis, among others.

Principle

When a material is irradiated with high-energy X-rays or other primary electrons, it can emit secondary X-rays. The energy of these emitted X-rays is characteristic of the difference in energy between the excited electron shells in an atom. By measuring the energy and intensity of these X-rays, it is possible to determine the elemental composition of the analyzed volume.

Instrumentation

The primary components of an EDX system include an electron microscope (either a scanning electron microscope (SEM) or a transmission electron microscope (TEM)), an X-ray detector, and a data processing system. The electron microscope is used to focus a beam of electrons onto a small area of the sample. When the electron beam interacts with the sample, it generates X-rays, which are then detected by the X-ray detector. The data processing system analyzes the detected X-rays and provides qualitative and quantitative information about the sample's composition.

Applications

EDX is widely used in various fields for material characterization, including:

• Materials Science: To analyze metals, glasses, ceramics, and polymers for research and quality control.
• Semiconductor Industry: For the characterization of semiconductor devices and materials.
• Geology and Mining: To identify minerals and their composition.
• Forensic Science: In the analysis of trace evidence, such as glass, paint, and fibers.
• Environmental Science: For the detection of pollutants and the study of atmospheric particles.

Advantages and Limitations

The main advantages of EDX include its non-destructive nature, the ability to perform both qualitative and quantitative analysis, and its applicability to a wide range of materials. However, it also has limitations, such as the requirement for vacuum conditions in most cases, potential sample charging, and the inability to detect very light elements (e.g., hydrogen, helium) effectively.

See Also

• X-ray fluorescence
• X-ray crystallography
• Scanning electron microscope
• Transmission electron microscope