Question: What is the cool looking ray gun thingy in your pictures?

Rebecca Scott answered on 20 Jun 2013:

It is cool 🙂

It is a pXRF (portable X-ray Fluorescence Spectrometer). It is a non-destructive method of looking at the composition of a material. The machine fires X-rays at the sample and excites the electrons around the atoms in the material. The electrons are arranged in shells around the atom and as an electron gets excited it breaks out of the shell it is in and another electron drops down into its place. As the 2nd electron drops into place it releases energy which we call fluorescence. All elements have their own characteristic pattern of fluorescence. So, the machine measures what fluorescence the material gives off and tells us how much of each element is present in the sample.

It can be used on most inorganic materials. I once looked for fake pound coins with it because fake ones don’t always have the right amount of copper, nickel and zinc in them.