X-Ray Fluorescence

Introduction

X-ray fluorescence (XRF) is an analytical technique used to determine the elemental composition of a material. It is a type of emission spectroscopy that uses the inherent properties of atoms to identify and quantify the presence of different elements.

The Principle of XRF

When a material is exposed to an incident beam of X-rays, the atoms in the material can absorb this energy and become excited. This causes the ejection of an electron from an inner orbital, creating a vacancy. To fill this vacancy, an electron from an outer orbital drops down, releasing energy in the form of an X-ray photon. This process is known as fluorescence.

The energy of the emitted X-ray photon is characteristic of the element from which it originated, as it equals the difference between the energy levels of the two involved orbitals. Therefore, by measuring the energies of the X-ray photons emitted from a sample, we can determine its elemental composition.

XRF Spectroscopy

In XRF spectroscopy, an X-ray detector measures the number of emitted photons at each energy level to produce a spectrum. The presence of a peak at a certain energy indicates the presence of a particular element in the sample. The height or area of the peak can be used to determine the concentration of that element.

The basic equation for XRF is:

where is the energy of the emitted X-ray photon, and and are the energies of the outer and inner electron orbitals, respectively.

Applications

XRF is a non-destructive technique that can be used to analyze a wide range of materials, including solids, liquids, and powders. It is widely used in many areas of research and industry, including materials science, environmental analysis, archaeology, and the oil and gas industry.

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