Radioactive dating in archaeology
An accelerator mass spectrometer has a run time of a few hours per sample.Lastly, it must be noted that AMS measurements usually achieve higher precision and lower backgrounds than radiometric dating methods.From these data, concentration ratio of the isotopes can be known to allow evaluation of the level of fractionation.The greatest advantage that AMS radiocarbon dating has over radiometric methods is small sample size.Thanks to nuclear physics, mass spectrometers have been fine-tuned to separate a rare isotope from an abundant neighboring mass, and accelerator mass spectrometry was born.A method has finally been developed to detect carbon 14 in a given sample and ignore the more abundant isotopes that swamp the carbon 14 signal.
At the end of an AMS run, data gathered is not only the number of carbon 14 atoms in the sample but also the quantity of carbon 12 and carbon 13.
Burning the samples to convert them into graphite, however, also introduces other elements into the sample like nitrogen 14.
When the samples have finally been converted into few milligrams of graphite, they are pressed on to a metal disc.
After pretreatment, samples for radiocarbon dating are prepared for use in an accelerator mass spectrometer by converting them into a solid graphite form.
This is done by conversion to carbon dioxide with subsequent graphitization in the presence of a metal catalyst.