SCAR Technique

ppqSense developed a laser spectroscopy technique that is sensitive enough to detect radiocarbon dioxide molecules at very low mole fractions with an all-optical setup, that is more compact and less expensive than AMS and much “cleaner” than LSC, the two currently most widely used techniques for measuring radiocarbon.

The new approach, named Saturated-absorption CAvity Ring-down (SCAR), makes use of molecular absorption saturation to enhance the sensitivity with respect to conventional cavity ring-down spectroscopy.

By combining SCAR with narrow-linewidth mid-IR quantum cascade lasers (QCLs) and our state of the art electronics we can achieve an unprecedented limit in trace gas detection, down to a few parts-per-quadrillion, ppq, (10-¹⁵) mole fraction.

C14-SCAR analyzes the CO2 gas produced by burning the sample and retrieves the mole fraction of 14C by measuring the spectral area of a given molecular transition of 14CO2 molecule.

If the sample is taken from a modern living being, the measured 14C mole fraction will be close to the so-called natural abundance or Modern Carbon (MC) mole fraction. This corresponds to 100 percent of Modern Carbon, i.e. 100 pMC. A similar measurement taken on a sample containing only fossil carbon will not show any signal corresponding to the 14CO2 transition, since no 14C is present: this corresponds to 0 percent of Modern Carbon, 0 pMC.