V-cavity stabilized quantum cascade laser-based cavity ringdown spectroscopy for rapid detection of radiocarbon below natural abundance

Mid-infrared laser absorption spectroscopy utilizing a high-finesse optical cavity enables high precision trace analysis of gas molecules. In particular, detection radiocarbon ( 14 C) based on ringdown using quantum cascade (QCL) is gaining attention as an alternative to accelerator mass spectrometry. This paper reports compact-packaged narrow-linewidth QCL system resonant feedback from external V-shaped cavity. Based frequency noise analysis, the derived linewidth 44 kHz for 100 μs integration time with capability perform seamless scanning around 10 GHz. We installed this within table-top spectrometer CO 2 . A single-shot limit 1.2 × −9 cm −1 Hz −1/2 leading detectable abundance evaluated 0.2 in fraction modern C 10-s averaging was achieved. rapid suitable various applications requiring analysis.