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.
Figure 1 shows the TEM image of the gold nano particles we obtained by reducing chloroauric acid using sodium citrate.
![Figure 1. TEM image of colloidal gold nanoparticles](https://blogs.imperial.ac.uk/fonsmad2015-velox/files/2015/07/Gold-Nanoparticles-300x200.jpg)
Our next TEM is scheduled for the 22nd July, so we shall keep you updated with our AuNPs progression.