Radiokarbonalder

Radiokarbonalder, commonly known as radiocarbon age, refers to the age estimate of organic material derived from the decay of the unstable isotope carbon‑14 (C‑14). C‑14 is produced in the upper atmosphere by cosmic ray interactions with nitrogen, and it becomes incorporated into living organisms through photosynthesis and the food chain. When an organism dies, it stops taking in C‑14, and the isotope begins to decay with a half‑life of approximately 5,730 years. By measuring the remaining C‑14 content relative to stable carbon isotopes (C‑12 and C‑13) in a sample, scientists can calculate the time elapsed since the death of the organism, expressed in years before present (BP), conventionally using 1950 as the present year.

The analysis is performed using accelerator mass spectrometry (AMS) or radiometric decay counting. Sample preparation includes removing contaminants, processing into pure carbon or oxide forms, and converting to graphite or gaseous CO₂. The resulting C‑14/C‑12 ratio is compared to the modern standard atmosphere ratio, expressed as the "punchhole" method or through calibration curves like IntCal. Because the atmospheric concentration of C‑14 has varied over time due to solar activity, geomagnetic field changes, and nuclear testing, calibration curves are essential for converting raw radiocarbon years to calendar years. Today’s calibration data extend back roughly 55,000 years, beyond which the C‑14 signal becomes too weak for reliable dating.

Radiokarbonalder is a cornerstone technique in archaeology, paleoclimatology, and geology, allowing the dating of artifacts, charcoal, bone, pollen, and other organic remains. Its precision falls within ±100–300 years for typical samples, but accuracy can be compromised by reservoir effects, contamination, or sample size limitations. Ongoing developments in isotope measurement sensitivity and calibration database expansion continue to refine the reliability of radiocarbon dating.