What is carbon isotope analysis? Why is it possible to date the archeology?

According to level 3 knowledge, there are always variations called chemical isotopes. Isotopes will have the same number of protons and electrons but different numbers in neutrons. It is this difference that leads to different number of blocks as well as physical / chemical properties.

Isotopes are divided into two types, stable isotopes and radioactive isotopes. Radioisotopes are radioactive, meaning their nucleus is unstable and will be modified. For Carbon, we have 3 main isotopes: 12C, 13C and 14C , of which 14C is radioactive isotope and 12C and 13C are stable isotopes. 14Cs are always created in the atmospheric layers due to cosmic rays, which have neutrons and interact with 14 nitrogen to create 14C and protons.

This 14C undergoes chemical reactions to form CO ₂ from which organisms are absorbed during photosynthesis or digestion.

The half-life is an important parameter for people to determine the age of antiques.

Another concept closely related to this is the half-life. This is the time when a quantity after transformation is only half of its original amount. And the half-life is an important parameter for people to determine the age of antiques.

Dating by carbon-14 isotopes

Because organic compounds always exist Carbon, so this method is commonly used when it is necessary to determine the absolute age of an organic sample. Besides carbon, there are many radioactive isotopes of other substances used in the general isotopic determination method.

This method was invented by Willard Libby on the cover in 1940 and it was this that earned him a Nobel Prize in Chemistry in 1960. Here is the principle that this method works.

• The carbon isotope 14 is a radioactive isotope with a half-life of 5730 years. That is to take a simple example if you have 4 14C seeds, after 5730 years, we only have 2 seeds left. (or 1gam to 0.5gam for example)
• When a plant or animal lives, they will have approximately 14C in the body approximately in the atmosphere or ocean (for aquatic organisms) at that time. However, after death, 14C was reduced due to decay.
• Carbon levels used to compare in the past can be estimated, or taken from known facts by other indirect methods, such as counting the number of rings in a tree and then calculating the 14C in the trunk. for example that tree. Or one could get another reference sample of the same type but have a timeline in the present for reference.
• Radiometric measurements were performed to determine what the current decay of the sample was, in order to determine the age of the specimen by comparing the ratio with 12 ° C or with the radioactivity of the same sample. on. This is considered the basic way.

By some simple formulas, it is easy to find the age of this wood sample is over 17 thousand years (17190 years). However, this method is usually not used for specimens dating back more than 50 thousand years because at this time, the remaining 14C is not enough to give an accurate result, at this time people will use another method. .

In addition to Carbon, people can also use Uranium or Potassium-Argon (used for soil samples) for analysis. By these methods, it is also used to know the age of the Earth or meteorites hitting the Earth.

In addition to Carbon, people can also use Uranium or Potassium-Argon (used for soil samples) for analysis.

Talking about 5730 numbers is also quite interesting. In an article published in 1949 by Mr. Libby, he stated that the half-life of 14C is 5720, the error of 47 years. But after that, this number was changed to 5568 within 30 years and used over a period of 10 years. Until 1960, it was revised to 5730 error for 40 years now.