Theoretical investigation of the water/corundum (0001) interface

摘要

For the reliable long-term modeling of the actinide migration in geological formations, theadsorption/desorption properties and the reactivity of mineral surfaces must be understood at themolecular level. The adsorption of radioisotopes at mineral surfaces of the aquifer is an importantprocess that leads to the retention of contaminants such as radionuclides. Their transport by theground water is either retarded or even completely inhibited by the presence of such a surface.Accordingly, this subject is of main importance for the safety assessment of nuclear wasterepositories. As part' of a joint theoretical/experimental effort, the interaction of water with thecorundum (0001) surface is studied using several theoretical methods (Moller–Plesset perturbationtheory, coupled cluster singles doubles with triplet corrections, as well as density functional theory).We focus in this study on the determination of the bond lengths and tilt angles of the surface OHspecies and their respective vibrational frequencies. The theoretical results are confirmed bysubsequent simulation of the interface selective nonlinear sum frequency spectra. The excellentagreement of the simulated with the experimental spectra allows an assignment of the observedpeaks in the sum frequency spectra of the water/corundum (0001) interface on the basis of ourtheoretical data. In this theoretical study we are able to give a unique interpretation of the observedsum frequency spectra of the water/corundum (0001) interface