際際滷

際際滷Share a Scribd company logo

Carbon Dating 2.pptx

Download as PPTX, PDF
S
sachin k

Carbon dating determines the age of organic material by measuring the amount of carbon-14 remaining in the material. Carbon-14 is continually produced in the atmosphere and absorbed by plants and animals during life. After death, the amount of carbon-14 decreases steadily as it decays, allowing the age of once-living materials to be estimated by measuring the amount remaining. The half-life of carbon-14 is about 5730 years, so its levels are measured to calculate elapsed time since death. Carbon dating is widely used in archaeology and geology to estimate the age of ancient living things.

1 of 21
Downloaded 27 times
Carbon Dating Presented by, Sachin K 1st year M.sc Dos in Molecular Biology Guided by, Ms B.M Ranjitha Dept of Molecular Biology
Content Introduction History Carbon Dating Principle of carbon dating Life Cycle Of Carbon 14 Methods of carbon dating Application Summary
INTRODUCTION All carbon atoms have 6 protons in the nucleus,but the nucleus may also contain 6, 7, or 8 neutrons. Their are 3 naturally occuring isotopes of carbon on earth, 1.carbon-12 : Stable nucleous (99% of all natural carbon) 2.carbon -13 : Stable nucleous (1%) 3.Carbon -14 : Unstable radioactive isotopes (Wher 1 in 1012 carbon atoms in the atomosphere is C-14)
History The carbon-14 method was developed by the American physicist Willard Frank Libby and his team in 1946 at the University of Chicago. He determined the half life to be 5568 years 賊 30 years and it is popularly known as libby half life. This half life has later been re-determind by Godwin as 5730 賊 40 years which is known as the Cambridge half life. In 1960, Mr. Willard F. Libby was awarded the Nobel Prize in Chemistry in recognition of his efforts to develop radiocarbon dating.
Carbon dating It is one of the form of Radiometric dating and also refered as Radiocarbon dating or carbon-14 dating. This method used for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
Principle Carbon 14 is continually being formed in the upper atmosphere by the effect of cosmic ray neutrons on nitrogen 14 atoms. It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle. Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes. When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay. Radiocarbon dating is essentially a method designed to measure residual radioactivity.
Life Cycle Of Carbon 14
Marine cycle
Contd.... Animals get their C-14 dose from the food that they consume. When the organism (or a tissue) dies absorption of C-14 ceases and the amount of C-14 gradually decays.. The half-life of the decay of C-14 to nitrogen is 5730 years so the concentration halves every 5730 years. HALF-LIFE : The time taken for half a radioactive sample to decay into something else. Radioactive carbon (C-14) 硫 decays to nitrogen (N14) by emitting an electron (e) and an antineutrino ( v-) with no mass or charge.
10g 5g 2.5g 1.25g 0.625g 1 half life = 5730 years t 1/2 t 1/2 t 1/2
Carbon dating in laboratory
Methods of measuring C-14 There are two basic methods, 1. Radiometric : Radiometric dating method is used to detect beta particles from the decay of carbon 14 atoms. using a gas proportional counter (a form of Geiger counter) or a liquid scintillation counter. It is cheap and It takes about a month to achieve satisfactory statistics. 2. AMS (Accelerator mass spectrometer): Accelerator mass spectrometers count the number of carbon 14 atoms present in the sample. It is expensive and it takes about a week. It requires only about a gram. It is a good method for dating specific samples.
Accelerator mass spectrometer at Lawrence Livermore National Laboratory, California Liquid Scintillation conter
Application Carbon dating is useful to archeologists when they need to know the approximate date of a fossil or any other object. carbon dating is used to find the ages of trees, mummies, fossils, or other organic material Carbon-14 is used to study the passage of carbon dating photosynthesis in plants.
contd.... Radiocarbon dating of sacred mummies from ancient Egypt. Radiocarbon dating can be used to date carbon containing pigment like charcoal, it was even useful in dating cave paintings. Samples that have been radiocarbon dated since the inception of the method include, charcoal, wood, twigs, seeds, bones, shells, leather, peat lake mud, soil, hair, pottery, pollen wall paintings, corals, blood residues, fabrics paper or parchment, resins, and water.
Contd.... Ancientin ink : Iceman Otzi has worlds oldest tattoos (Chinchoro mummy) 61 tattoos on the Icemans body. Ancient Quran manuscript (1,500 years old)
contd.... Prehistoric horse decorates the walls of lascaux Cave in France. (40.000BC to 8000 BC ) Burial site with items dug up from the Sanauli site in Baghpa (3800 yrs old)
Limitation This technique used only for dating organic material It cannot be used to date rocks (except carbonacious rocks) Maximum age limit for C-14 dating is 52,000 to 62,000 years. Several physical, chemical, and biological processes can cause contamination. Carbon exchange between the sample and the atmosphere is a common cause of contamination in bone, wood, and shell samples.
Measurement and reporting dates The radiocarbon measurement is termed as conventional radiocarbon age (CRA). Uncalibrated radiocarbon measurements are usually reported in years BP(Before present) where 0 (zero), BP is defined as AD 1950. BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating, where BP is defined as AD 1980. Half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, Although it is less accurate.(to avoide inconsistencies or errors when comparing carbon-14 test )
Summary C-14 method is used for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The half-life of the decay of C-14 to nitrogen 14 is 5730 years so the concentration halves every 5730 years. When the organism (or a tissue) dies absorption of C-14 ceases, and the amount of C-14 gradually decays in every half life. carbon dating is used to find the ages of trees, mummies, fossils, or other organic materials.
Thank you

More Related Content

Carbon Dating 2.pptx

  • 1. Carbon Dating Presented by, Sachin K 1st year M.sc Dos in Molecular Biology Guided by, Ms B.M Ranjitha Dept of Molecular Biology
  • 2. Content Introduction History Carbon Dating Principle of carbon dating Life Cycle Of Carbon 14 Methods of carbon dating Application Summary
  • 3. INTRODUCTION All carbon atoms have 6 protons in the nucleus,but the nucleus may also contain 6, 7, or 8 neutrons. Their are 3 naturally occuring isotopes of carbon on earth, 1.carbon-12 : Stable nucleous (99% of all natural carbon) 2.carbon -13 : Stable nucleous (1%) 3.Carbon -14 : Unstable radioactive isotopes (Wher 1 in 1012 carbon atoms in the atomosphere is C-14)
  • 4. History The carbon-14 method was developed by the American physicist Willard Frank Libby and his team in 1946 at the University of Chicago. He determined the half life to be 5568 years 賊 30 years and it is popularly known as libby half life. This half life has later been re-determind by Godwin as 5730 賊 40 years which is known as the Cambridge half life. In 1960, Mr. Willard F. Libby was awarded the Nobel Prize in Chemistry in recognition of his efforts to develop radiocarbon dating.
  • 5. Carbon dating It is one of the form of Radiometric dating and also refered as Radiocarbon dating or carbon-14 dating. This method used for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
  • 6. Principle Carbon 14 is continually being formed in the upper atmosphere by the effect of cosmic ray neutrons on nitrogen 14 atoms. It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle. Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes. When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay. Radiocarbon dating is essentially a method designed to measure residual radioactivity.
  • 7. Life Cycle Of Carbon 14
  • 9. Contd.... Animals get their C-14 dose from the food that they consume. When the organism (or a tissue) dies absorption of C-14 ceases and the amount of C-14 gradually decays.. The half-life of the decay of C-14 to nitrogen is 5730 years so the concentration halves every 5730 years. HALF-LIFE : The time taken for half a radioactive sample to decay into something else. Radioactive carbon (C-14) 硫 decays to nitrogen (N14) by emitting an electron (e) and an antineutrino ( v-) with no mass or charge.
  • 10. 10g 5g 2.5g 1.25g 0.625g 1 half life = 5730 years t 1/2 t 1/2 t 1/2
  • 11. Carbon dating in laboratory
  • 12. Methods of measuring C-14 There are two basic methods, 1. Radiometric : Radiometric dating method is used to detect beta particles from the decay of carbon 14 atoms. using a gas proportional counter (a form of Geiger counter) or a liquid scintillation counter. It is cheap and It takes about a month to achieve satisfactory statistics. 2. AMS (Accelerator mass spectrometer): Accelerator mass spectrometers count the number of carbon 14 atoms present in the sample. It is expensive and it takes about a week. It requires only about a gram. It is a good method for dating specific samples.
  • 13. Accelerator mass spectrometer at Lawrence Livermore National Laboratory, California Liquid Scintillation conter
  • 14. Application Carbon dating is useful to archeologists when they need to know the approximate date of a fossil or any other object. carbon dating is used to find the ages of trees, mummies, fossils, or other organic material Carbon-14 is used to study the passage of carbon dating photosynthesis in plants.
  • 15. contd.... Radiocarbon dating of sacred mummies from ancient Egypt. Radiocarbon dating can be used to date carbon containing pigment like charcoal, it was even useful in dating cave paintings. Samples that have been radiocarbon dated since the inception of the method include, charcoal, wood, twigs, seeds, bones, shells, leather, peat lake mud, soil, hair, pottery, pollen wall paintings, corals, blood residues, fabrics paper or parchment, resins, and water.
  • 16. Contd.... Ancientin ink : Iceman Otzi has worlds oldest tattoos (Chinchoro mummy) 61 tattoos on the Icemans body. Ancient Quran manuscript (1,500 years old)
  • 17. contd.... Prehistoric horse decorates the walls of lascaux Cave in France. (40.000BC to 8000 BC ) Burial site with items dug up from the Sanauli site in Baghpa (3800 yrs old)
  • 18. Limitation This technique used only for dating organic material It cannot be used to date rocks (except carbonacious rocks) Maximum age limit for C-14 dating is 52,000 to 62,000 years. Several physical, chemical, and biological processes can cause contamination. Carbon exchange between the sample and the atmosphere is a common cause of contamination in bone, wood, and shell samples.
  • 19. Measurement and reporting dates The radiocarbon measurement is termed as conventional radiocarbon age (CRA). Uncalibrated radiocarbon measurements are usually reported in years BP(Before present) where 0 (zero), BP is defined as AD 1950. BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating, where BP is defined as AD 1980. Half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, Although it is less accurate.(to avoide inconsistencies or errors when comparing carbon-14 test )
  • 20. Summary C-14 method is used for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The half-life of the decay of C-14 to nitrogen 14 is 5730 years so the concentration halves every 5730 years. When the organism (or a tissue) dies absorption of C-14 ceases, and the amount of C-14 gradually decays in every half life. carbon dating is used to find the ages of trees, mummies, fossils, or other organic materials.