In physics , optically stimulated luminescence OSL is a method for measuring doses from ionizing radiation. It is used in at least two applications:. 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. The ionizing radiation produces electron-hole pairs: Electrons are in the conduction band and holes in the valence band. The electrons that have been excited to the conduction band may become entrapped in the electron or hole traps. Under the stimulation of light, the electrons may free themselves from the trap and get into the conduction band.
Luminescence Dating: Applications in Earth Sciences and Archaeology
This paper aims to provide an overview concerning the optically stimulated luminescence OSL dating method and its applications for geomorphological research in France. An outline of the general physical principles of luminescence dating is given. A case study of fluvial sands from the lower terrace of the Moselle valley is then presented to describe the range of field and laboratory procedures required for successful luminescence dating.
optically stimulated luminescence (OSL) is detected during their exposure to light at any fixed wavelength. Hence, there exist TL and OSL dating techniques.
Luminescence dating, particularly using optically stimulated luminescence OSL , is revolutionizing Quaternary and archaeological science because it allows dating of sediments and artifacts that perhaps 10 years ago could not be dated. The lab has produced more than OSL ages from years to , years for aeolian, fluvial, lacustrine, and marine sediments, as well as pottery, artifacts and secondary carbonate.
Chronologies have been developed for archaeological sites in Botswana and the U. As the OSL of a sediment is quickly lost when exposed to sunlight tens of seconds many sediments are bleached lack an OSL signal when deposited and buried. After deposition these sediments accumulate luminescence which can be measured allowing the age of burial to be determined. There is now convincing evidence that many glacial, fluvial, aeolian, and even shallow marine sediments can be dated by OSL techniques.
The upper limit of age by OSL is largely determined by the annual dose on the sediment which is related to it’s content of uranium, thorium and potassium. Low levels of radioactive isotopes in the sediment lead to very slow saturation of quartz and feldspar grains by released electrons and so ages in excess of ka may be possible. Your gift is important to us and helps support critical opportunities for students and faculty alike, including lectures, travel support, and any number of educational events that augment the classroom experience.
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Luminescence and ESR Dating
The OSL optically stimulated luminescence dating method exploits dosimetric properties of grains of minerals naturally occurring in sediments and man-made materials. In archaeology the OSL method is used to date pottery and other heated materials e. When compared with the radiocarbon method it makes possible dating objects containing no organic matter or originating in periods for which the radiocarbon method is less accurate due to the shape or lack of the calibration curve.
Crystalline rock types and soils collect energy from the radioactive decay of cosmic uranium, thorium, and potassium Electrons from these substances get trapped in the mineral’s crystalline structure, and continuing exposure of the rocks to these elements over time leads to predictable increases in the number of electrons caught in the matrices. But when the rock is exposed to high enough levels of heat or light, that exposure causes vibrations in the mineral lattices and the trapped electrons are freed.
Luminescence dating is a collective term for dating methods that encompass thermoluminescence TL and optically stimulated luminescence OSL dating techniques. OSL is also less commonly referred to as optical dating, photon stimulated luminescence dating or photoluminescence dating.. Luminescence dating methods are based on the ability of some mineral grains to absorb and store energy from environmental ionizing radiation emanating from the immediate surroundings of the mineral grains as well as from cosmic radiation.
When stimulated these minerals, generally referred to as dosimeters, will release the stored energy in the form of visible light; hence the term luminescence. Measuring the energy and determining the rate at which the energy accumulated allows an age representing the time that has elapsed since the energy began accumulating to be determined.
Geochronology/Optically stimulated luminescence
Introduction How do we measure the OSL signal? How do we measure the radiation dose rate? Another way of dating glacial landforms is optically stimulated luminescence dating OSL. OSL is used on glacial landforms that contain sand, such as sandur or sediments in glacial streams.
6. Thermoluminescence (TL) dating of pottery and burned stones, and. OSL dating of sedimentary quartz and feldspar grains, are the methods most commonly.
Over the last 60 years, luminescence dating has developed into a robust chronometer for applications in earth sciences and archaeology. The technique is particularly useful for dating materials ranging in age from a few decades to around ,—, years. In this chapter, following a brief outline of the historical development of the dating method, basic principles behind the technique are discussed. This is followed by a look at measurement equipment that is employed in determining age and its operation.
Luminescence properties of minerals used in dating are then examined after which procedures used in age calculation are looked at. Sample collection methods are also reviewed, as well as types of materials that can be dated. Continuing refinements in both methodology and equipment promise to yield luminescence chronologies with improved accuracy and extended dating range in the future and these are briefly discussed. Luminescence – An Outlook on the Phenomena and their Applications. Luminescence dating refers to age-dating methods that employ the phenomenon of luminescence to determine the amount of time that has elapsed since the occurrence of a given event.
In this chapter, the application of luminescence techniques in dating geological and archaeological events is examined. Generally, the term luminescence dating is a collective reference to numerical age-dating methods that include thermoluminescence TL and optically stimulated luminescence OSL dating techniques. Other terms used to describe OSL include optical dating [ 1 ] and photon-stimulated luminescence dating or photoluminescence dating [ 2 ].
Luminescence dating methods are based on the ability of some dielectric and semiconducting materials to absorb and store energy from environmental ionizing radiation. In earth sciences and archaeological applications, the dielectric materials are usually minerals such as feldspar and quartz.
Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits
The Luminescence Dating and Dosimetry Laboratory is developing new techniques for application to the dating of artefacts and deposits from sites that range widely in terms of chronological period, geographic location and material type. Recent work as focused on optically stimulated luminescence OSL techniques, in particular a novel experimental approach to the measurement of single grain OSL.
A study produced, for the first time, absolute dates for a range of brick stupas located within the hinterland of Anuradhapura , contributing to the further development of a brick monument chronology for the region. Ongoing work is examining whether unfired clay bricks from various sites can be dated accurately.
Recent work as focused on optically stimulated luminescence (OSL) techniques, in particular a novel experimental approach to the measurement of single grain.
Optical : Relating to the use of visible or near-visible light. Stimulated : To excite with a stimulus light or heat. Optically stimulated luminescence : The emission of light from crystalline materials when stimulated by light following previous absorption of energy from radiation. Luminescence dating consists of a family of analytical methods, most of which are used in archaeological research.
Encyclopedia of Geoarchaeology Edition. Contents Search. Reference work entry First Online: 12 August How to cite. Optical : Relating to the use of visible or near-visible light Stimulated : To excite with a stimulus light or heat Luminescence : The emission of light Optically stimulated luminescence : The emission of light from crystalline materials when stimulated by light following previous absorption of energy from radiation.
DRI Luminescence Laboratory
The DRI E. The DRILL is a research laboratory dedicated to fundamental investigations in the luminescence properties of earth materials, and to the application of luminescence dating techniques to geomorphological, geological, and archeological problems. The DRILL welcomes collaboration with research institute and university faculty, consultants, and government agency researchers. The DRILL research staff can collaborate on proposals, contribute to grant writing, and consult on study design.
OSL dating method is superior to the radiocarbon dating method, as it eliminates a common ‘old-carbon’.
Please reference: Mallinson, D. Optically stimulated luminescence is a method of determining the age of burial of quartz or feldspar bearing sediments based upon principles of radiation and excitation within crystal lattices, and stems from the fact that imperfections in a crystal lattice have the ability to store ionizing energy Aitken , ; Botter -Jensen et al. Radiation within sediments comes from alpha, beta, and gamma radiation emitted during the decay of U, U, Th, 40 K, and 87 Rb, and their daughter products, both within the mineral grains and in their surroundings Lian , , and from cosmic rays Figure 1.
Under controlled laboratory conditions, assuming the sample was collected under light-restricted conditions, controlled exposure of the sample to photons yields a luminescence response the equivalent dose, D e , the intensity of which is a function of the dose rate within the sediment, and the length of time the sample was exposed to the background radiation. In order to measure the age, two factors must be known; 1 the environmental dose rate, and 2 the laboratory dose of radiation that produces the same intensity of luminescence as did the environmental radiation dose the equivalent dose.
Dividing the equivalent dose by the dose rate yields time. Samples for OSL analysis are typically collected from opaque core tubes aluminum or black pvc tubes that are pushed into the sediment using coring equipment vibracore , geoprobe , etc. Samples are then extracted for processing under dark-room conditions.
This is followed by sieving, heavy liquid Li- or Na- polytungstate separation, and sometimes magnetic separation to concentrate quartz sands of the appropriate size.