On the 16th July, we booked to use the Transmission Electron Microscope (TEM) to characterise the gold nanoparticles we had been synthesising since week 1. Transmission Electron Microscopy is a microscopy technique which allows us to measure small objects (to the order of a few angstrom 10-10 m) by focussing a thin beam of electrons onto a sample. The beam of electrons travel through the sample and depending on the density of the sample present, some of the electrons are scattered. The unscattered electrons hit a fluorescent screen at the bottom of the microscope and give rise to a image of the sample.