Uses of mass spectrometry in carbon dating
These methods relied on the observation of a decay of the radioactive carbon atoms.
When a C atom decays, it emits a beta particle, which can be counted in a gas by the electrical pulse it generates.
In 1977, as already mentioned, two papers (Nelson et al., 1977 and Bennett et al., 1977) were published simultaneously in Science, reporting on the development of such a method, which added a particle accelerator into the mass spectrometer to produce an accelerator mass spectrometer.
This technique has allowed the measurement of radiocarbon in samples of much less than a milligram, or more than a thousand times less material than is needed for the older counting methods.
The first attempt to use radiocarbon for dating was the work of Libby and his co-workers, 50 years ago, using counting of the decays of the radioactive isotope.This creates an error in the "raw" age of about 2 percent.Since nearly all applications where the precise age is needed require calibration, this difference is removed in the calibration process]. Accelerator mass spectrometry (AMS) is a technique for direct measurement of the concentration of radioisotopes.A radiocarbon measurement can be obtained on a sample of ~0.5 mg of carbon, and measured to 40 years in uncalibrated radiocarbon age in a measurement time of 3040 minutes on each sample.
Search for uses of mass spectrometry in carbon dating:
Carbon-14 is produced in the upper atmosphere by nuclear reactions induced by cosmic rays on nitrogen (see Fig. Nearly all the carbon in the atmosphere is present as carbon dioxide (CO in the atmosphere maintains an equilibrium with the biosphere and the oceans.