A Lifetime of Work on Defect Modelling for Luminescence

To fully appreciate the contributions of Professor Watanabe to studies of luminescence, it is important to recall how, during his lifetime, not only have experimental facilities changed dramatically, but also there have been (and still are) many conflicting models as to the relevant lattice sites. This current overview summarises some of these factors. Indeed, several powerful early techniques have gone into abeyance, but there is a real potential benefit in resurrecting them. Equally, early key experiments on the existence of long-range interactions are frequently ignored, to the detriment of many models of lattice sites related to luminescence. Despite difficulties with defect site models and understanding luminescence processes, empirical data have nevertheless been effective in many applications from archaeological dating, luminescence dosimetry, and the development of modern phosphors for use across a wide range of modern applications. Improved models that include long-range features will inevitably add to this empirical progress.