An entirely new method of nanoparticle chemical synthesis  based on liquid droplet irradiation with ultralow energy electrons. We have developed a source of electrons with energies close to thermal which leads to a number of important and unique benefits. The charged species, including the growing nanoparticles, are held in an ultrathin surface reaction zone which enables extremely rapid precursor reduction. (Nano Lett, 2017, 17, 1336).