Radiocarbon dioxide detection using cantilever-enhanced photoacoustic spectroscopy

We report sub-parts-per-billion level radiocarbon dioxide detection using cantilever-enhanced photoacoustic spectroscopy. The 14C/C ratio of samples is measured by targeting a 14CO2 absorption line with minimal interference from other CO2 isotopes. Using a quantum cascade laser as a light source allows for a compact experimental setup. Measurements of sample gases with 14CO2 concentrations as low as 100 parts-per-trillion are presented. The Allan deviation demonstrates a noise equivalent concentration of 30 parts-per-trillion at an averaging time of 9 minutes. The achieved sensitivity validates this method as a suitable alternative to more complex optical detection methods for radiocarbon dioxide detection used so far, and can be envisioned for future in situ radiocarbon detection.