Istituto Nazionale di Ottica-CNR (INO-CNR) and European Laboratory for Non-Linear Spectroscopy (LENS, Sesto Fiorentino, Italy.
Phys Rev Lett. 2011 Dec 30;107(27):270802. doi: 10.1103/PhysRevLett.107.270802.
Radiocarbon ((14)C) concentrations at a 43 parts-per-quadrillion level are measured by using saturated-absorption cavity ringdown spectroscopy by exciting radiocarbon-dioxide ((14)C(16)O(2)) molecules at the 4.5 μm wavelength. The ultimate sensitivity limits of molecular trace gas sensing are pushed down to attobar pressures using a comb-assisted absorption spectroscopy setup. Such a result represents the lowest pressure ever detected for a gas of simple molecules. The unique sensitivity, the wide dynamic range, the compactness, and the relatively low cost of this table-top setup open new perspectives for ^{14}C-tracing applications, such as radiocarbon dating, biomedicine, or environmental and earth sciences. The detection of other very rare molecules can be pursued as well thanks to the wide and continuous mid-IR spectral coverage of the described setup.
利用饱和吸收腔衰荡光谱，通过在 4.5 μm 波长处激发放射性碳-二氧化碳((14)C(16)O(2))分子，可测量达到 43 万亿分之一水平的放射性碳((14)C)浓度。使用梳状辅助吸收光谱装置，将分子痕量气体传感的极限灵敏度推至阿托巴压力。这一结果代表了简单分子气体所检测到的最低压力。这种台式装置具有独特的灵敏度、宽动态范围、紧凑性和相对较低的成本，为^{14}C 追踪应用开辟了新的前景，例如放射性碳年代测定、生物医学或环境与地球科学。由于所描述的装置具有宽而连续的中红外光谱覆盖范围，因此也可以检测其他非常稀有的分子。
