Study of the photochemical oxidation of mercury: application to the separation of mercury isotopes

Investigation of the mechanism of the isotopic photo-oxidation of mercury has enabled the existence of an unstable excited complex (HgO2*) to be demonstrated. In the presence of butadiene, this complex gives stable mercuric oxide. Butadiene does not act purely as an interceptor for oxidizing species. By theoretical investigation of the complex HgO2*, its electronic structure (3PI) could be determined and its energy of formation (4.6 eV) predicted. The phenomenon of photodecomposition of mercuric oxide was demonstrated and its importance evaluated. The results obtained made it possible to develop an apparatus for the photochemical separation of the isotopes of mercury, whose efficiency is acceptable despite the low quantum yield. Since the method for the photochemical separation of the isotopes has only been studied for mercury, an identical study for other elements, and particularly for elements of the same group as mercury (zinc, cadmium), could lead in the future to new aspects in the study of photochemical mechanisms