Quartz optically stimulated luminescence configurational coordinate model

Abstract

In a recent study using pulsed stimulation we revealed that optically stimulated luminescence (OSL) and photo-transferred thermoluminescence (PTTL) in quartz are characterised by a common pulse response. We interpreted this result as indicating that both emissions are governed by the same detrapping mechanisms. In the present study we develop a common configurational coordinate model to describe the mechanisms. Within our model we identify the energy associated with the thermal assistance effect as the vibrational energy of the ground state of the dimer that represents the trap. Further, we model the OSL stimulation process as an optical transition between a vibrationally-excited ground state level and a dimer excited state. By introducing additional luminescence parameters, we reveal that the processes that underlie thermal quenching and the room temperature OSL response to pulsed stimulation can be represented by competing modes which empty the excited state. In particular, we find that the room temperature pulse response can be modelled in terms of an optical transition from the excited state to a lower antibonding level from which a hole is ejected. In contrast, thermal quenching is explained by excited state vibrational dissociation at large dimer component separations.