Carbon dating in archaeology
Accelerator mass spectrometry (AMS) is a modern radiocarbon dating method that is considered to be the more efficient way to measure radiocarbon content of a sample.
The principal modern standard used by radiocarbon dating labs was the Oxalic Acid I obtained from the National Institute of Standards and Technology in Maryland. Around 95% of the radiocarbon activity of Oxalic Acid I is equal to the measured radiocarbon activity of the absolute radiocarbon standard—a wood in 1890 unaffected by fossil fuel effects.
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.
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.