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.
Carbon 14 dating millions
At this stage, other negatively charged atoms are unstable and cannot reach the detector.
The negatively charged carbon atoms, however, move on to the stripper (a gas or a metal foil) where they lose the electrons and emerge as the triple, positively charged carbon atoms.
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.
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.
Due to the sensitivity of accelerator mass spectrometers, carbon dating small particles like blood particles, a grain, or a seed have been made possible.
Accelerator mass spectrometry also takes less time to analyze samples for carbon 14 content compared to radiometric dating methods that can take one or two days.
Burning the samples to convert them into graphite, however, also introduces other elements into the sample like nitrogen 14.