Non adult chat - What is luminescence dating
Free electrons are generated within the mineral matrix by exposure to ionizing radiation from the radioactive decay of daughter isotopes in the 235U, 238U and 232Th decay series, and a radioactive isotope of potassium, 40K, with lesser contributions from the decay of 85Rb and cosmic sources.
The radioactive decay of 40K releases beta and gamma radiation, whereas the decay in the U and Th series generates mostly alpha particles and some beta and gamma radiation.
In the past 15 years there have been significant advances in luminescence dating with the advent of single aliquot and grain analysis, and associated protocols with blue/green diodes that can effectively compensated for laboratory induced sensitivity changes (Murray and Wintle, 2003; Wintle and Murray, 2006; Duller, 2012) and render accurate ages for the past ca. Most recently, the development of protocols for inducing the thermal-transfer of deeply trapped electrons has extended potentially OSL dating to the 106 year timescale for well solar-reset quartz and potassium feldspar grains from eolian and littoral environments (Duller and Wintle, 2012).
The age range for pottery and other ceramics covers the entire period in which these materials have been produced.
The typical range for burnt stone or sediment is from about 100 to 300,000 years.
The guidelines will help archaeologists and site investigators to assess whether luminescence dating will be of value in providing chronological information for understanding their site.
Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation.
This property of these minerals can be used during the process of mineral identification at rock outcrops in the field, or in the laboratory.
==References== ==External links== *[ database of luminescent dyes] Category: Light sources Category:19th-century neologisms Texte soumis à la licence CC-BY-SA.
Ensuing research in the 1970s documented that marine and other sediments with a prior sunlight exposure of hours to days were suitable for thermoluminescence dating (Wintle and Huntley, 1980).
Discoveries in the 1980s and 1990s that exposure of quartz and feldspar grains to a tunable light source, initially with lasers and later by light emitting diodes, yield luminescence components that are solar reset within seconds to minutes, expanded greatly the utility of the method (Huntley et al., 1985; Hütt et al., 1988; Aitken, 1998).
Diagram above: In silicate minerals, when radiation interacts with the crystal (Irradiation), energy pushes an electron into the conduction band and leaves a ‘hole’ in the valence band.