These projects, predominantly performed at the Dalton Cumbrian Facility (DCF), investigate the radiation chemistry of (condensed) phase water. For irradiation experiments on ices under ultra-high vacuum conditions, see Ice Dynamics.
We tend to adsorb a controlled number of water layer on oxide nanoparticles such as ZnO or ZrO2 and irradiate these (gamma or alpha) before quantifying the amount of H2 or O2 being produced. It turns out that after irradiation of the water-coated nanoparticles, not only does the irradiation induce radiolysis of the adsorbed water, but excitons within the nanoparticle trasnfer their energy across the interface and increase the overall radiolysis yield significantly.
We are also investigating the 'opposite' process, i.e. the radiation-induced recombination of H2 and O2 to form water, both in the pure gas-phase as well as catalytically enhanced by metal nanoparticles. This is supported by kinetic modelling of the overall system. Who would have thought that for the simple gas-phase reaction 2 H2 + O2 -> 2 H2O, more than 200 elementary reactions play their part, mainly due to the involvement of not only radicals, but also excited states and ions and electrons (due to the presence of the gamma field).
Using ZnO nanoparticles, we have also observed - rather unusually - the formation of gas-phase O2 NOT from adsorbed water, but from the ZnO itself, which changes colour from pure white to a slightly yellow-ish colour as it turns to ZnO1-x.