Luminescence contains information about the structural state of metals and defects at ultradilute concentrations. Furthermore, minerals have geological timescales over which to achieve perfect states of defect order, making them ideal materials in which to study luminescence. In principle, light emission is a powerful tool for determining defect structure, but interpreting such data is challenging since we have an incomplete understanding of luminescence in many minerals, and how features such as coordination state and symmetry are encoded within it.
Here we present data on two spectroscopic methods in quartz and feldspar. We have measured the light emitted during implantation by ions, known as ion beam luminescence (IBL) or ionoluminescence (IL). We model closely the implantation using Monte-Carlo simulations and, by changing acceleration potential, current and nature of the ions (i.e. H+, He+, N+), we change implantation depth (i.e. bulk vs surface responses) and the relative proportions of ionisation, vacancy and phonon formation. Comparing ions (H+) and molecules (H2+) contrasts luminescence from excitation of ground states with excitation of excited states, i.e. double excitation. We also monitor the change in luminescence as a function of implantation dose. This allows us to determine whether the changes are consistent with the proposed nature of the luminescence centres. Since most natural minerals have significant radiation damage, we also gain insights into how luminescence of real minerals differs from synthetic mineral analogues. The development of synchrotron radiation allows advances in x-ray excited optical luminescence (XEOL, also known as radioluminescence, RL). X-irradiation results in ionisation but not atomic displacements, in contrast to IBL. By comparing IBL and XEOL we deconvolute responses that derive from vacancy formation and atomic recoils.