A new analytical model to fit both fine and coarse grained quartz luminescence dose response curves

Abstract

We address two issues: (a) the choice of suitable analytic forms for curve fitting quartz OSL-SAR dose response data and (b) possible physical interpretations of the difference between fine (4–11 μm) and coarse (63–90 μm) grain samples. We start with a phenomenological model with three levels: an OSL-active trap, a deep trap, and a radiative center. This model yields a simple analytic form for the dose response under the optically stimulated luminescence-single-aliquot regenerative dose (OSL-SAR) protocol. By comparing with experimental data from nine quartz samples, we show that this form provides excellent agreement and may, in some cases, be better than the commonly-used double-saturating-exponential form despite this form having fewer adjustable constants. Further, because this analytic form is derived from a model, physical parameters can be inferred from the curve fits. In particular, concentrations for the OSL-active and deep electron traps can be computed and the variation in concentrations of these traps between samples is discussed. Within this model, the difference between fine and coarse grain samples is consistent with the OSL-active trap being a surface trap as opposed to a volume trap.