X-Ray Fluorescence Spectroscopy (XRF) Explained – Elemental Analysis Technique


How to measure the elemental composition of a material that can be a metal alloy, ceramic, polymer or even something out of this world? The technology for elemental analysis exists today and one of the most widely used methods for that purpose is called X-ray fluorescence spectroscopy Welcome to Captain Corrosion, My name is Maido and in this video you will learn the basics of this technique and at the end of the video I will use this spectrometer over here to measure the elemental composition of a 300 year old coin So let´s get started! In x-ray fluorescence spectroscopy an x-ray source is used to irradiate the sample with x-ray radiation If the energy of this radiation is sufficient then it will interact with the atoms inner shell electrons causing them to be kicked out Almost immediately a relaxation process takes place where one of the outer shell electrons falls into the inner shell As a result a specific amount of energy is released in the form of electromagnetic radiation The energy of the emitted x-rays depends on the energy difference between the higher and lower states and therefore the radiation also carries information about the atom So if we can measure the energy and intensity of this characteristic x-ray radiation that comes out of the material during the relaxation process then we can also get information about the elemental composition of the sample For measuring the energy and intensity of the emitted characteristic x-ray radiation there are two possible spectrometer setups In the case of the energy-dispersive analysis a detector is used that can sort the energies of photons This setup is often favoured due to its low cost and fast measurement times Its main problem however is low accuracy due to broad overlapping peaks The wavelength-dispersive analysis uses a crystal to select which wavelength radiation actually enters the detector In that crystal the x-rays are scattered from different layers of atoms which means that some beams travel a longer optical path For a radiation with a defined wavelength the criteria of Bragg´s law is met at a certain angle and all the scattered beams are in the same phase which means that constructive interference takes place So if the angle is changed by moving the crystal and the detector it is possible to scan in a wide spectral range and find out which wavelength characteristic x-ray radiation comes out of the sample With such a setup the peaks are narrower and their overlapping is significantly reduced Therefore the accuracy in wavelength-dispersive analysis is much greater than in the case of the energy-dispersive analysis The main disadvantages of this setup are longer measurement times and significantly higher cost of the spectrometer Now it´s time for the demonstration where I will measure the exact elemental composition of this 300 year old Russian coin For that purpose the sample is first cleaned with high-purity deionized water and organic solvents Next, the cleaned substrate is placed into the spectrometer on a special holder and the measurement is started Right now the sample atoms are excited with x-ray radiation and the resulting characteristic x-rays measured This process can take tens of minutes or even longer Eventually a spectrum is obtained where the energy and intensity of the emitted characteristic x-rays can be seen Based on that data it is possible to calculate the elemental composition of the material and in the case of this sample we are dealing with a copper coin The high content of oxygen and carbon originate from the rust layer while the smaller quantities of other elements such as arsenic may indicate that the coin had a colourful history Measuring the composition of a material however is just one option for this system It can also be used to map the elements on a larger substrate measure the mass thickness of thin films or even detect very small amounts of unusual elements which can be handy in analysing crime scene evidences There are also smaller, hand-held, versions of this spectrometer in the market Although they are less accurate than their larger cousins they are much cheaper and more comfortable for performing quick analysis My name is Maido and I thank You for watching our video about the basics of x-ray fluorescence spectroscopy If you want to see more videos like this then hit the subscribe button over here and check out the Captain Corrosion YouTube channel Also, be sure to see the videos description for additional information and leave your thoughts and questions in the comment section below

23 thoughts on “X-Ray Fluorescence Spectroscopy (XRF) Explained – Elemental Analysis Technique

  1. the gun x-ray machine and the end of clip is completely different with your spectroscopy machine that you test with  coin, the coin x-rayis  two way and x-ray gun one way.
    in fact xray return from your device as you said doing by reflex and xray gun completely different operation have.
    how ever, thank for your clip hope to show more item result and let know the result print directly coming from machine and his application or need more element to do by other device or machine to have result percentage

    thanks
    seyed

  2. Eh, it's a surface analysis technique – for 'accurate' elemental analysis of composition I would still prefer ICP-MS/OES.

  3. it's a surface analysis technique – for 'accurate' elemental analysis of composition I would still prefer ICP-MS/OES.

  4. Hey. Very nice video. Can you please tell me how much would a machine like the one you're presenting costs ? It certainty looks expensive !

  5. is it posible to take a measurement value and put it on a totally different program for PC?? or is it posible to create an interface between a PC program and the machine or a PLC and the machine??

  6. So after the element loses its inner shell electron, how does the entire element (not the inner shell) get its electron back?

  7. Would one be able to use this method to measure the elemental composition of the soil, if so, how would you suggest preparing the sample?

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