Compared to conventional radiocarbon techniques such as Libby's solid carbon counting, the gas counting method popular in the mid-1950s, or liquid scintillation (LS) counting, AMS permitted the dating of much smaller sized samples with even greater precision.
Regardless of the particular 14C technique used, the value of this tool for archaeology has clearly been appreciated.
They have masses of 13 and 14 respectively and are referred to as "carbon-13" and "carbon-14." If two atoms have equal numbers of protons but differing numbers of neutrons, one is said to be an "isotope" of the other.
Carbon-13 and carbon-14 are thus isotopes of carbon-12.
Isotopes participate in the same chemical reactions but often at differing rates.
When isotopes are to be designated specifically, the chemical symbol is expanded to identify the mass (for example, C is not stable.
Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.
Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.
All carbon atoms have a nucleus containing six protons.Recall that atoms are the basic building blocks of matter.Atoms are made up of much smaller particles called protons, neutrons, and electrons.Radiocarbon dating is especially good for determining the age of sites occupied within the last 26,000 years or so (but has the potential for sites over 50,000), can be used on carbon-based materials (organic or inorganic), and can be accurate to within ±30-50 years.Probably the most important factor to consider when using radiocarbon dating is if external factors, whether through artificial contamination, animal disturbance, or human negligence, contributed to any errors in the determinations.