Define radioactive carbon dating

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.

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A more recent innovation is the direct counting of c14 atoms by accelerator mass spectrometers (AMS).

The sample is converted to graphite and mounted in an ion source from which it is sputtered and accelerated through a magnetic field.

Most samples require chemical pre-treatment to ensure their purity or to recover particular components of the material.

The objective of pre-treatment is to ensure that the carbon being analyzed is native to the sample submitted for dating.

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.

During the lifetime of an organism, the amount of c14 in the tissues remains at an equilibrium since the loss (through radioactive decay) is balanced by the gain (through uptake via photosynthesis or consumption of organically fixed carbon).

However, when the organism dies, the amount of c14 declines such that the longer the time since death the lower the levels of c14 in organic tissue.

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.

Any organic material that is available in sufficient quantity can be prepared for radiocarbon dating.

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