Giovanni Giusfredi

TL;DR: The ultimate sensitivity limits of molecular trace gas sensing are pushed down to attobar pressures using a comb-assisted absorption spectroscopy setup, and this result represents the lowest pressure ever detected for a gas of simple molecules.

TL;DR: A comprehensive investigation of the frequency-noise spectral density of a free-running midinfrared quantum-cascade laser is presented, providing direct evidence of the leveling of this noise down to a white- noise plateau, corresponding to an intrinsic linewidth of a few hundred hertz.

TL;DR: In this article, cavity ring-down spectroscopy with the sample gas in saturated-absorption regime is proposed to decouple and simultaneously retrieve empty-cavity background and absorption signal.

TL;DR: In this article, an intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) was employed for sensitive trace gas detection in the mid-infrared spectral region.

TL;DR: In this article, the authors presented a compact and simple spectroscopic apparatus, based on saturated-absorption cavity ring-down, approaching the ultimate AMS sensitivity, which measured radiocarbon dioxide concentration down to a few parts per quadrillion by use of a heterodyne-spectroscopy system with two quantum cascade lasers at 4.5 μm and a high-finesse cavity with the sample gas cooled down to 170 K.