Carbon-14 Dating

Introduction

14C-dating (radiocarbon dating) is a tool for estimating the age of biological materials that originated in the past, such as fossils of living organisms. The age is determined by comparing the volume of 14C in a sample to globally recognized criteria. 14C-dating is a major discovery of the twentieth century and no other has revolutionized science as much as it has. The 14C-dating method has been used in archeological research as well as human sciences to either disprove or prove hypotheses. Furthermore, 14C-dating has been used in geology, geophysics, oceanography, hydrology, paleoclimatology, biomedicine, and atmospheric science for many years. In all the studies mentioned above, the 14C-dating has been used for several years in the geology, geophysics, oceanography, hydrology, paleoclimatology, biomedicine, and atmospheric science. In all the studies mentioned above, the 14C-dating has exhibited significance in the estimation of the age of different organic materials. The information about the age of organic materials has assisted in understanding the world in the past years; people can certainly claim how life was thousands of years ago. 14C-dating, also called radiocarbon dating uses three principles; (AMS) accelerator mass spectroscopy, (LSC) liquid scintillation counting, and the (GPC) gas proportional counting. In the modern science laboratories; Oxalic Acid I, & Oxalic Acid II are used as the standards. The 14C-dating measurements are given as the Conventional Radiocarbon Age. It is important to note that 14C-dating is exclusively applicable to organic matter; it cannot be sued for non-organic materials such as metals (Beta).

Discovery

14C-dating was discovered in 1946 via the efforts of Willard Libby who proposed a new technique of determining the age of organic substances by measuring their amount of 14C. The discovery occurred when Willard was working as a professor in the Chemistry Department, Institute for Nuclear Studies (the now called University of Chicago) in the USA. By then, the 14C had just been discovered as a radioactive isotope of carbon. The 14C-dating was a significant discovery that allowed the scientists to estimate the ages of materials that originated from living things. Willard’s discovery was embraced with novelty especially by the archeology practitioners. The radiocarbon dating brought sanity in the chronological arrangement of historical and geographical data (Lindblom).

Basic Principles of 14C-Dating

14C dating uses a radioactive carbon isotope (14C). The carbon -14 is an unstable and weak radioactive isotope as opposed to the other stable carbon isotopes (12C, and 13C). The active 14C forms continuously in the upper atmosphere because of the cosmic ray reactions on the nitrogen 14 atoms. 14C is readily oxidized in the air to produce carbon (IV) oxide that eventually enters the carbon-cycle.

Throughout the lifetime, plants and animals consume the 14C atoms combined with carbon dioxide. When the plants and animals die, they cease to exchange carbon with the biosphere part of the carbon cycle. Therefore, the 14C contained in the dead plant and animal materials starts to reduce. The rate of decrement of the 14C content in dead plants and animals occurs at a rate that is determinable using the radioactive decay laws.

The basic idea behind the radiocarbon dating is the measurement of the residual radioactivity. Through the estimation of the amount of carbon -14 remaining in an organic sample, one can estimate the age of the organism at the point of death. Therefore, it is vital to note that 14C dating determines the time when the organism died rather than the time when the organic material was used. For this reason, the 14C dating gives estimates of ages rather than exact ages (Beta).

Methods of Measuring in 14C- Dating

The measurement of the 14C contents in a sample occurs via three main principles; accelerator mass spectroscopy, liquid scintillation counting, and gas proportional counting. The gas proportional counting (GPC) is a type of conventional radiometric dating. The GPC involves the counting of the β-particles (fragments) emitted from a sample. The β-particles come from the radiocarbon decay. During the gas proportional counting, the sample is converted to CO2 (g) before the measurement inside the gas proportional counters (Beta).

The liquid scintillation counting (LSC) was famous in the 1960s. The liquid scintillation counting (LSC) uses samples in liquid form in which a scintillator is added. The purpose of a scintillator is to produce the flashlight after interacting with the β-particles. A vessel holding the sample is passed between two photomultipliers, and a count is made if and only if both devices record a flashlight (Beta).

The third method, accelerator mass spectroscopy (AMS) is the most recent method of carbon dating. The accelerator mass spectroscopy (AMS) is more efficient than either of the methods mentioned earlier. The AMS involves direct counting of the 14C content in a sample concerning the contents of 12C and 13C in the sample. The accelerator mass spectroscopy (AMS) technique doesn’t count the β-particles; instead, it counts the actual number of carbon atoms in a sample as well as the ratio of the isotopes (Beta).

Advantages of radiocarbon dating

The radiocarbon dating is applicable in determining the age when an organism died. The improvement in the 14C dating especially using the accelerator mass spectrometry provides a higher accuracy in determination of age because it uses the relative proportion of 14C and 12C in a sample. The 14C dating has contributed immensely to the bridging of gaps that existed in evolutionary data. The 14C dating has significance in the determination of ages for organic products that existed between 50,000 and 400 years ago. The 14C dating techniques have eliminated the contradictions between the religious calendars such as the Cristian and the Muslim Calendars. Other than the theoretical explanation of times and ages, the radiocarbon dating has insisted on the more tangible measurement of time. For this reason, 14C dating has provided the chronological data for the historical events that had no occurrence calendars (Renfrew).

Disadvantages of radiocarbon dating

However, the success of 14C dating is affected by some drawbacks such as the limitations on only organic substances. The radiocarbon dating is also affected by the fact that the analysis of the mixture of samples is difficult. The contamination of ancient organic substances due to geographical and climatic variations lead to the reduction of the accuracy of the radiocarbon dating. There are also contradicting information concerning the radiocarbon dating ages of materials subjected to the analysis at different times. For this reason, several scientists and authors have raised concern over the accuracy of radiocarbon dating. The radiocarbon dating technique uses expensive devices. Hence it is viewed as a wastage of the scarce resources. The changes in the earth’s magnetic field have been quoted as a source of errors in the past 14C dating. Another source of errors in previous 14C dating is the variations in the amount of carbon that an organism can access. Moreover, the variations in the structure of the earth’s atmosphere have been linked with errors in the 14C dating data. The changes mentioned above have resulted in lower quantities of 14C. As a result, the ratio of the 14C and 12C in a sample assumes a constant that give falsified data (Lee).

Conclusion

The 14C dating uses the radioactive carbon isotopes to determine an estimated age of organic substances. Willard Libby, a professor at the University of Chicago is credited for discovering the technique in 1942. The principles behind the 14C- dating are counting of the proportion of 14C present in a sample concerning the amount of 12C, and 13C. 14C dating is based on three key measurement techniques; accelerator mass spectroscopy (AMS), liquid scintillation counting (LSC), and gas proportional counting (GPC). 14C- dating is a significant milestone in the archeological, historical, and geographical as well as paleoclimatology studies. However, 14C dating is only applicable for substances that originate from living organisms. The 14C dating cannot be used for non-organic substances such as metals. The application of carbon dating is also affected by the fact that it doesn’t give the age when the organic substance was used but rather the age at which the organism died.

Works Cited

Beta. How Does Carbon Dating Work. 2017. Web. 4 December 2017.

Lee, Robert E. “Radiocarbon: Ages in Error.” Anthropological Journal of Canada (2013): 9-29. Print.

Lindblom, Alison Romig and Keith. “Chemists and Chemistry that Transformed Our Lives .” American Chemical Society (2016): 1-2. Print.

Renfrew, Colin. “Why Is Radiocarbon Dating Important To Archaeology?” California Department of Parks and Recreation (2017): 2-3. Print.