This is the clock that permits levels of c14 in organic archaeological, geological, and paleontological samples to be converted into an estimate of time.
The measurement of the rate of radioactive decay is known as its half-life, the time it takes for half of a sample to decay.
the field deflects atoms of different masses differently (heavier atoms deflect less).
Targets tuned to different atomic weights count the number of c12, c13, and c 14 atoms in a sample.
The diminishing levels via decay means that the effective limit for using c14 to estimate time is about 50,000 years. Subsequent work has shown that the half-life of radiocarbon is actually 5730 ± 40 years, a difference of 3% compared to the Libby half-life.
However, to avoid confusion all radiocarbon laboratories continue to use the half-life calculated by Libby, sometimes rounding it to 5570 years.
Most samples require chemical pre-treatment to ensure their purity or to recover particular components of the material.
Plants take up c14 along with other carbon isotopes during photosynthesis in the proportions that occur in the atmosphere; animals acquire c14 by eating the plants (or other animals). Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials. Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.Pre-treatment seeks to remove from the sample any contaminating carbon that could yield an inaccurate date.Acids may be used to eliminate contaminating carbonates.