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.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.Accelerator mass spectrometers need only as little as 20 milligrams and as high as 500 milligrams for certain samples whereas conventional methods need at least 10 grams in samples like wood and charcoal and as much as 100 grams in bones and sediments.Accelerator mass spectrometers typically need sample sizes lesser than conventional methods by a factor of 1,000. Hence, because of its ability to analyze samples even in minute amounts, accelerator mass spectrometry is the method of choice for archaeologists with small artifacts and those who cannot destroy very expensive or rare materials.Mass spectrometers detect atoms of specific elements according to their atomic weights.
If the charged particles have the same velocity but different masses, as in the case of the carbon isotopes, the heavier particles are deflected least.
There are essentially two parts in the process of radiocarbon dating through accelerator mass spectrometry.
The first part involves accelerating the ions to extraordinarily high kinetic energies, and the subsequent step involves mass analysis.
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.
An accelerator mass spectrometer has a run time of a few hours per sample.