Dating, by carbon

Mechanical intrusion is the penetration of the matter to be dated by carbon of a different age from that of the sample itself if not taken into account, mechanical intrusion, too, leads to erroneous ages. The penetration of rootlets from growing plants into buried specimens, the infiltration of windblown organic matter, and the accidental insertion of fibers from brushes or other instruments used to clean a sample are examples of likely modern carbon intrusions into prospective samples, which lead to assigning to a sample later dates than the true ones old carbon intrusions, such as those caused by the penetration of carbonate minerals from groundwater, or of petrol or oil from excavating tools, on the other hand, are conducive to assigning earlier dates than the true ones. 

Wooden artifacts from Easter Island can be dated by carbon-14 analysis. 

Ammo acid racemization (Section 27 2) A method for dating archeological samples based on the rate at which the stereo chemistry at the a carbon of ammo acid components is ran domized It is useful for samples too old to be reliably dated by decay... 

Edwards RL, Cheng H, Murrell MT, Goldstein SJ (1997) Protactinium-231 dating of carbonates by thermal ionization mass spectrometiy imphcations for Quaternary climate change. Science 276 782-785... 

Most bone is, at present, dated by radiocarbon dating the carbon-containing components of the bone (see Textbox 52). Relatively large samples are... 

For more recent dating processes carbon dating is used. With a half-life of 5717 years 14C dating relies on the replenishment of the 14C parent species, which occurs by neutron capture. The process occurs in the atmosphere as a result of bombardment of the Earth with neutrons ... 

Preliminary Studies on Dating Polar Ice by Carbon-14 and Radon-222... 

In 1946, Frank Libby of the Institute of Nuclear Sciences in Chicago initiated the dating of carbon-based artifacts by analysing the extent of radioactive decay. 

Pseudo-cationic polymerisations are reactions in which an alkene is inserted between the positive carbon atom and the negative heteroatom of a polar bond at the growing end of a polymer chain, without the formation of a carbenium ion they do not differ essentially from the well-known additions of esters to alkenes. The theory of these reactions was devised by Gandini and Plesch [2] and has been brought up to date by Plesch [3]. 

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