X-ray fluorescence (XRF) is one of the elementsal analysis methods widely adopted due to its high, non-destructive and fast nature. XRF detects the element's type and composition by measuring the intensity of secondary X-rays that are released after the sample has absorbed X-rays. This technology doesn't need elaborate sample preparation methods like acid dissolution or alkali fusion and so makes the analysis much easier.

Fundamentals of XRF

X-ray fluorescence (XRF) is a popular technique for measuring the elements of substances. Here is a rundown of what XRF is and what its fundamentals are, how it works, and how it differs from other elemental analysis methods.

Basic Principles

The principle of X-ray fluorescence is that X-rays bounce off the samples of atoms. If high-energy X-rays are applied to a sample, then those X-rays strike the sample's atoms. In particular, the energy of the X-rays is such that they kill the inner electrons (usually K or L shell electrons) of the atoms in the sample and leave a vacancy. These holes are filled with outgoing electrons, and the electrons re-enter the medium of high energy to low energy, exchanging energy. This energy escapes in the form of fluorescent radiation – so-called secondary X-rays (or fluorescent X-rays), whose energy spectrum correlates exactly with the excited constituent.

All elements are energy distributed differently, and by measuring the energy of these fluorescent radiations we can detect the elements in the sample. Moreover, by estimating the wavelength of these fluorescent radiations, the amount of every element in the sample can be measured quantitatively.

Key Components

A typical XRF elemental analyser is composed of the following main elements:

1. X-ray source: It's the heart of the XRF analyzer, and it's what creates the high-energy X-rays. Molybdenum target X-ray tubes and silicon target X-ray tubes are typical X-ray sources. These X-ray sources can be energetic enough to excited the sample atoms.

2. Sample holder: The sample holder is what fix and holds the sample to be tested. Usually it is designed to withstand X-ray exposure and the sample doesn't move during the measurement.

3. Detector: The detector measures the fluorescence radiation from the sample. Typical detectors are silicon drift detectors (Si-Detector) and Geiger counters. How sensitive and resolvable the detector is directly determines the quality of the analysis output.

4. Data processing: The data processing system usually consists of computers and software that would process and process the detector's data. When combined with those, they can be used to provide a report of the sample elemental content.