Thermoluminescence dating of sand dunes in rajasthan
The traditional OSL method relies on optical stimulation and transfer of electrons from one trap, to holes located elsewhere in the lattice – necessarily requiring two defects to be in nearby proximity, and hence it is a destructive technique.
The problem is that nearby electron/hole trapping centres suffer from localized tunneling, eradicating their signal over time; it is this issue that currently defines the upper age-limit for OSL dating In 1994, the principles behind optical and thermoluminescence dating were extended to include surfaces made of granite, basalt and sandstone, such as carved rock from ancient monuments and artifacts.
Ioannis Liritzis, the initiator of ancient buildings luminescence dating, has shown this in several cases of various monuments.
The radiation dose rate is calculated from measurements of the radioactive elements (K, U, Th and Rb) within the sample and its surroundings and the radiation dose rate from cosmic rays.
For quartz, blue or green excitation frequencies are normally used and the near ultra-violet emission is measured.It uses various methods to stimulate and measure luminescence.It includes techniques such as optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and thermoluminescence dating (TL).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.
The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried.