XRF

This post is about X Ray Fluorescence Spectroscopy. If the Name sounds too complicating or sounds uninteresting feel free to ignore this post. Stephen Hawking says in the preface to his book-"The Universe in a Nutshell", that his publisher advised him saying that the inclusion of an equation or technical details will cut down his readership by half. So he didn't do it. But I'm going to write about X Ray Fluorescence Spectroscopy in this blog, and I don't care about the readership. Besides, at the moment I'm writing this post, I don't have any readers! I 'm writing this as a way of remembering what I learned in preparing a presentation on XRF under the module Analytical Methods.
Back to the topic. When high energy electromagnetic radiation-usually in the form of X Rays, strikes a material, The atoms in the material may get ionized. If the energy is sufficient, an atom can lose an electron from one of its lower orbitals. This causes an instability in the atom and therefore an electron from a higher orbital fills in the gap created by the dismissed electron. This causes a release of energy again in the form of X rays but with lower energy than the primary, incident X rays. These secondary X rays are called Fluorescent X rays, and the phenomenon is named Fluorescence.
This released energy corresponds to the energy difference between the orbitals involved and is unique to the atoms of a particular element. This makes it possible, to identify the elements present in a sample by analyzing its fluorescent X rays. In fact, analyzing here means measuring the energy of the emitted radiation. This method of analysis is called X Ray Fluorescence Spectroscopy.
The XRF Spectrometer consists of the primary X ray Source, the sample, the detector and the computer. XRF Spectrometers are further classified into two types;
1. Energy Dispersive Spectrometers(EDS/EDX)
2. Wavelength Dispersive Spectrometers(WDS/WDX)
In the energy Dispersive type the fluorescent X rays are directly measured and is the faster and cheaper method. The Wavelength dispersive type uses an analyzer crystal to separate the different wavelengths before they are focused into the detector. This method the more sensitive method.
A variety of elements can be identified using XRF Spectroscopy and it is commonly used in Geo Chemical investigations and mineral analysis. Recent developments to this technique and emergence of handheld XRF Spectrometers has brought about its application in fields like forensics and archaeology as well. XRF Spectroscopy was recently used to analyze the painting techniques used by Leonardo Da Vinci in creating his world famous masterpiece-"Mona Lisa".