Optical detection of radiocarbon dioxide: first results and AMS intercomparison

The first results of an optical method for measuring radiocarbon concentrations, based on mid-infrared laser spectroscopy of a carbon dioxide gas sample, are presented with the theoretical bases explained in detail. The first measurements on modern and highly enriched samples show the extreme linearity of this technique over more than 5 decades. An intercomparison with accelerator mass spectrometry (AMS) is performed both for modern and C-14-dead samples, assessing the almost perfect agreement of their respectively measured concentration values. The main features of our technique are compared with liquid scintillation counting (LSC) and AMS, and future developments of the current setup are discussed.