Over the years, other secondary radiocarbon standards have been made.Radiocarbon activity of materials in the background is also determined to remove its contribution from results obtained during a sample analysis.There are three principal techniques used to measure carbon 14 content of any given sample— gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry.
By knowing how much carbon 14 is left in a sample, the age of the organism when it died can be known.
It must be noted though that radiocarbon dating results indicate when the organism was alive but not when a material from that organism was used.
American Chemical Society National Historic Chemical Landmarks.
Discovery of Radiocarbon Dating (accessed October 31, 2017). Sheridan Bowman, Radiocarbon Dating: Interpreting the Past (1990), University of California Press Accelerator Mass Spectrometry Radiocarbon Dating Calibration of Carbon 14 Dating Results Radiocarbon Dating and Bomb Carbon About AMS Dating Accelerator Mass Spectrometry (AMS) dating involves accelerating ions to extraordinarily high kinetic energies followed by mass analysis.
It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle.
Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.Liquid scintillation counting is another radiocarbon dating technique that was popular in the 1960s.In this method, the sample is in liquid form and a scintillator is added.When the stocks of Oxalic Acid I were almost fully consumed, another standard was made from a crop of 1977 French beet molasses.The new standard, Oxalic Acid II, was proven to have only a slight difference with Oxalic Acid I in terms of radiocarbon content.Standard errors are also reported in a radiocarbon dating result, hence the “±” values.