Tl dating laboratory
Because traps have different energy depths, some traps are not very stable at ambient temperatures and lose their electrons over the time period relevant to archaeology.Other traps are sufficiently deep that they are not easily emptied during the exposure to heat or light.Subsequent to zeroing, traps become refilled because of continued ionization by radioactivity and a latent luminescence signal steadily accumulates.In the laboratory the traps are again emptied and the intensity of the natural luminescence signal measured, TL or OSL, is proportional to the concentration of trapped charge that has accumulated.The external source of energy is naturally occurring, ionizing radioactivity (alpha, beta, gamma and cosmic radiation).The time lag can be understood by reference to solid state energy band theory.
The lack of organic remains makes them generally unsuitable for palaeobiological studies, and thus palaeomorphological dating has been the main method applied to determine their relative age.
Ionizing radiation excites electrons from the valence band, or ground state, across an energy gap to the conduction band where they are free to move about.
Energy levels within the gap cannot normally be occupied, but crystalline defects resulting in localized charge deficiencies allow occupation of metastable energy levels within the gap.
Located in the basement of Bessey Hall on UNL's City Campus, the Luminescence Geochronology Laboratory specializes in optically-stimulated luminescence (OSL) dating of Quaternary fluvial, eolian, and coastal deposits.
This "dark (amber-light only) lab" contains rooms for sample storage, sample preparation, and OSL readers. This lab primarily serves UNL faculty and graduate students, but collaborative research is ongoing with colleagues from other institutions.