As part of my PhD work I characterise nanomaterials using Energy-dispersive X-ray spectroscopy (EDX) in a Scanning Transmission Electron Microscope. We do this to obtain spatial information about the chemical composition of a sample on the nanoscale. Basically, an image is obtained by raster-scanning the electron beam and recording an X-ray spectrum in each position. This effectively gives a 3-dimensional dataset, where for each pixel a full spectrum is recorded. Since different elements emit X-rays at different energies, we can essentially make images of each element in a sample by extracting that part of the spectrum.