No abstract

The resonance excitation of excitons was used for the first time to activate photocatalytic redox reactions on ZnO. The sample activity was tested using the photoactivated oxygen isotope exchange (POIE), which can be used to predict both oxidation and reduction reactions. When the excitation energy is transferred to the surface by an electrically neutral exciton, then the main losses in transferring the photogenerated e–/h+ pairs due to recombination and to overcoming the surface potential barrier are strongly reduced. The radiative decay of an exciton on the ZnO surface is excluded by a 2D structure ZnO/ZnO1–x /O–, in which the exciton decays nonradiatively into a pair of long-lived (up to 8 × 103 s) electron and hole local states, on which in its turn a chemical reaction can take place. These centers decay at 450 K, emitting green luminescence. The exciton resonance excitation allows one to obtain the order-of-magnitude higher values of the efficiency of redox reaction compared to the case of interband excitation.

We report the growth of copper (I) chloride by atomic layer deposition. CuCl was deposited as nanoparticle arrays whose size and density were controlled by the process conditions. The nanoparticles were deposited using the self-limiting reaction of [bis(trimethylsilyl)acetylene]-(hexafluoroacetylacetonato)-copper(I) and hydrogen chloride. UV absorption measurements showed the characteristic Z1,2 and Z3 exciton absorption bands of CuCl. A strong UV emission was observed at 5 K from the free exciton Z3 and bound exciton I1 at 386.7 and 390.6 nm, respectively. A previously unreported visible emission band at 408 nm was also observed and attributed to the acceptor level of Cu vacancies.