Future directions of luminescence dating of quartz interesting headline for dating sites
An energy level diagram that illustrates how ionizing radiation creates luminescence centers in crystal lattices (redrawn from Ref. (a) Following irradiation, electrons are expelled from their original sites leaving holes behind.
(b) At appropriate sites, electrons are trapped while holes may become localized.
Evicted electrons that reach luminescence centers result in light being emitted. Illustration of glow-curves obtained following thermal stimulation. For quartz, TL measurement focused on a peak between 320 and 330°C whereas for feldspar, a peak at 310–320°C was analyzed.This review surveys previous attempts to develop luminescence techniques to date volcanic products and discusses the state of knowledge of the luminescence behaviour of the four principal materials currently used for luminescence dating of volcanic events.Particular attention is paid to the red luminescence emissions, primarily because of previous successes in using Red Thermoluminescence (RTL) of quartz and feldspar for dating volcanic products, for which the upper age limit may extend beyond a million years.(a) A signal yielded after the first heating of a quartz sample with trapped electrons (paleodose). Detection of TL signals was through a window with a center at 400 nm (violet).(b) A glow-curve from incandescence resulting from the second heating of the sample to a high temperature. Bleaching rates of quartz (q) and feldspar (f) stimulated using TL and OSL (green light) conducted by Godfrey-Smith et al. For the OSL, both quartz and feldspar used a green laser and a detection window of 380 nm which is violet to near-UV . Examples of TL (a, b) and OSL (c, d) emission spectra (adapted with permission from Ref. For TL spectra, the sharp rise in emissions beyond 650 nm is largely from incandescence (rather than from electrons evicted from traps). Main emission wavelengths for quartz and feldspars used in luminescence dating as well as wavelengths employed for stimulation.