The remarkable metrological history of 14C dating: From ancient Egyptian artifacts to particles of soot and grains of pollen

Abstract

Radiocarbon dating would not have been possible if 14C had not had the "wrong" half-life -a fact that delayed its discovery [1]. Following the discovery of this 5730 year radionuclide in laboratory experiments by Ruben and Kamen, it became clear to W. E Libby that 14C should exist in nature, and that it could serve as a quantitative means for dating artifacts and events marking the history of civilization. The search for natural radiocarbon was a metrological challenge; the level in the living biosphere [ca. 230 Bq/kg] lay far beyond the then current state of the measurement art. This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought lnc measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for "molecular dating" at the 10 ~tg to 100 lag level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the "bomb effect," that spawned new multidisciplinary areas of application, ranging from cosmic ray physics to oceanography to the reconstruction of environmental history.

Six Decades of Radiocarbon Dating in New World Archaeology

“…Both Kamen (1963) and Libby (1967) later noted that the first published suggestion of the existence of 14 C was contained in a paper by UC Berkeley physicist Franz Kurie [1907Kurie [ -1972 as what was initially viewed as a somewhat unlikely interpretation of the effect of neutron bombardment on nitrogen in a cloud chamber (Kurie 1934). By early 1940, Ruben and Kaman (1941), also at Berkeley, had determined that 14 C exhibited, as Currie (2003Currie ( , 2004 has characterized it, the "wrong" half-life of >1000 yr rather than from a few minutes to, at most, a few months as previously assumed. 18 They also deter-mined that thermal neutron bombardment on nitrogen was the favored mode of production.…”

Design Scenario for the Radioisotopic Estimation of the Biogenic Component of Airborne Particles

“…Of particular interest is the estimation of the secondary component of C and the apparent yield from atmospheric oxidation reactions of biogenic volatile organic compounds (VOCs). The method derives from a history of isotopic C experiments used in biogeochemistry, 1 combined with experience describing the phenomenological aspects of atmospheric C.…”