As with any radioactive particle it decays over time. Libby in 1948 at the University of Chicago, showed that C14, tested in his laboratory, decayed at the rate that, projected out, would cause half of its weight to be lost in 5568 years.
Hence, the term ‘half-life’ was given to radioactive substances.
Charcoal and wood are two of the most widely used materials for accelerator mass spectrometry (AMS) radiocarbon dating.
When radiocarbon dating a piece of wood or charcoal, the event dated is the growth of the tree ring.For radiocarbon dating to be reliable scientists need to make a number of vital assumptions.Firstly, Dr Libby assumed that C14 decays at a constant rate.Charcoal or wood could have been seasoned prior to the actual use of the timber that provided the sample that has been radiocarbon dated.Hardwoods that are very resilient against decay could have been reused in other structures in later years.The effects of these depositional processes may not be quantifiable but should not be overlooked because the carbon 14 dating results might turn out to be too old for the context being dated.About AMS Dating Accelerator Mass Spectrometry (AMS) dating involves accelerating ions to extraordinarily high kinetic energies followed by mass analysis.The time-width affects the way radiocarbon age is converted into calendar age for a sample.A wood’s time-width depends on the number of tree rings taken for radiocarbon dating.The radiocarbon method measures the rate of decay in the C14 of organic matter therefore estimating how long ago death occurred.Archaeologists can use this method to date bone, teeth, plants, seeds, burned food remains, coprolites, wood, and any artefact that contains organic materials such as an iron axe head (iron cannot be tested using C14) with a wooden handle or a bronze spear with a wooden shaft.