Concepts Deep time Geological history of Earth Geological time units. The method makes use of electrons trapped between the valence and conduction bands in the crystalline structure of certain minerals most commonly quartz and feldspar. Thermoluminescence is a common geochronology tool for dating pottery or other fired archeological materials, as heat empties or resets the thermoluminescent signature of the material Figure 1. The sediments with disagreeing ages were determined to be deposited by aeolian processes. Boyd, and Donald F. Please help improve this article by adding citations to reliable sources. From the conduction band, they may recombine with holes trapped in hole traps. One of the benefits of luminescence dating is that it can be used to confirm the authenticity of an artifact.
Luminescence dating refers to a group of methods of determining how long ago mineral grains were last exposed to sunlight or sufficient heating. It is useful to geologists and archaeologists who want to know when such an event occurred. It uses various methods to stimulate and measure luminescence. All sediments and soils contain trace amounts of radioactive isotopes of elements such as potassium , uranium , thorium , and rubidium. These slowly decay over time and the ionizing radiation they produce is absorbed by mineral grains in the sediments such as quartz and potassium feldspar. The radiation causes charge to remain within the grains in structurally unstable "electron traps". The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried. Stimulating these mineral grains using either light blue or green for OSL; infrared for IRSL or heat for TL causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral. Most luminescence dating methods rely on the assumption that the mineral grains were sufficiently "bleached" at the time of the event being dated. Single Quartz OSL ages can be determined typically from to , years BP, and can be reliable when suitable methods are used and proper checks are done. In multiple-aliquot testing, a number of grains of sand are stimulated at the same time and the resulting luminescence signature is averaged . The problem with this technique is that the operator does not know the individual figures that are being averaged, and so if there are partially prebleached grains in the sample it can give an exaggerated age . In contrast to the multiple-aliquot method, the SAR method tests the burial ages of individual grains of sand which are then plotted. Mixed deposits can be identified and taken into consideration when determining the age .
Luminescence is spontaneous emission of light by a substance not resulting from heat; or "cold light". It is thus luminescence dating wiki form of cold-body radiation. It can be caused by chemical reactionselectrical energysubatomic motions click stress on a crystal. This distinguishes luminescence from incandescencewhich is light emitted by a substance as a result of heating. Historically, radioactivity was thought of as a form of luminescence dating wiki, although it is today considered to be separate since it involves more than electromagnetic radiation.
The dials, hands, scales, and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as "luminising". Luminescence occurs in some minerals when they are exposed to low-powered sources of ultraviolet or infrared electromagnetic radiation for example, portable UV lampsat atmospheric pressure and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock outcrops in the fieldor in the laboratory.
From Wikipedia, the free link. For other uses, see Luminescence disambiguation. Abhandlung" On fluorescence and phosphorescence, first paperAnnalen der Physik34 : Berberan-Santos J. Radioactive Releases in the Environment: Impact and Assessment.
Retrieved 18 December Advances in Astronomy and Astrophysics Volume 6. Academic Press. Archived visit web page the original on Retrieved CS1 maint: archived copy as title link.
Regular Halogen Nernst. Carbon arc Klieg light Yablochkov candle. Theatrical Cinematic. Germicidal Grow light Infrared lamp Stroboscope Tanning. Display Decorative. Categories : Luminescence Light sources Words coined in the s.
Namespaces Article Talk. Views Read Edit View history. Help Community portal Recent changes Upload file. Download as PDF Printable version. Wikimedia Commons. Wikimedia Commons has media related to Luminescence. Incandescent Regular Halogen Nernst.