Radiocarbon Dating

Radiocarbon Dating

What is it?

• Dating’ is generally a method by which the age of an object is calculated.
• Radiocarbon dating amounts to a method in which dating happens using radiocarbon.
• Radiocarbon is a name for the isotope carbon­14.

About Carbon-14:

• It is created in the earth’s atmosphere when the cosmic rays coming from sources in outer space slam into the atoms of the gases and release the neutrons.
• After the release, these neutrons try to interact with the nitrogen­14 nitrogen isotope after which they can produce carbon­14.
• Since the cosmic rays are continuously passing through the earth’s atmosphere the resultant carbon­14 is also created constantly.
• Carbon­14 easily combines with atmospheric oxygen to form the radioactive carbon dioxide.
• This radioactive carbon dioxide then enters the bodies of plants (through photosynthesis), animals (herbivorous), and other biomass through carbon cycle.

Working mechanism of radiocarbon dating:

• When any organic entity similar to the human body is ‘alive’, it continuously exchanges carbon with its surroundings via breathing, consuming food, defecating, shedding skin, etc.
• Through the above activities, carbon­14 is both replenished as well as lost from the body, so its concentration in the body is almost constant and in equilibrium with its surroundings.
• When this particular individual dies, the body will no longer performs these activities and the concentration of carbon­14 in the body begins to decrease through radioactive decay.
• The more the amount of time passes, the more carbon­14 lost, and the less will remain.
• This decay rate can be calculated from theory.
• Therefore, Radiocarbon dating dates an object by calculating the amount of carbon­14 left by which scientists and/or computers use to calculate how long ago the body expired.

Tools of radiocarbon dating:

• The instrument to study the radioactive decay was the Geiger counter in 1940’s.
• It has Geiger­Muller tube which is connected to some electronics that interpret and display signals.
• The Geiger­Muller tube consists of a noble gas like helium or neon, and a rod that passed through the centre.
• A high voltage will be maintained between the tube’s inner surface and the rod.
• Since the gas is of insulating nature there will be no current passage between the two.
• But when energetic particles similar to those emitted during radioactive decay pass through the gas they can energise electrons in the gas’s atoms and thus produce an electric discharge.

Modern radiocarbon dating working:

• The modern radiocarbon dating method is more sophisticated and advanced.
• One of the most sensitive dating setups uses accelerator mass spectrometry (AMS) that work with organic samples as little as 50 mg.
• In this method Scientists use ‘regular’ mass spectrometry to isolate ions which have the same mass­to­charge ratio.

How did radiocarbon dating change science?

• Radiocarbon dating gave the ability to attach approximate numerical dates to organic remains.
• Due to this the effects of radiocarbon dating on the fields of archaeology and geology have come to be called as the “radiocarbon revolution”.
• In India, Radiocarbon dating is also of political significance where researchers and politicians have invoked its use to date objects retrieved from temples and mosques.