PNNL

Abstract

Aluminum-bearing minerals show different hydrogen evolution and dissolution properties when subjected to radiation, but the complicated sequence of events following interaction with high-energy radiation is not understood. To gain insight into the possible mechanisms of hydrogen production in nanoparticulate minerals, we study the electronic response of three common aluminum-bearing minerals with varying hydrogen content: gibbsite (Al(OH)3), boehmite (AlOOH), and alumina (Al2O3) using electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and first-principles electronic structure calculations. We find that the amount of hydrogen has only a small effect on the number and spectrum of photoexcitations in this class of materials. The highly anisotropic mobility of valence band holes, however, suggests that the differences in radiolytic behavior are related to differences in hole-mediated chemistry at the lateral faces of mineral particles.