Oxygen-Isotope Exchange between CO and NO with Implications for Atmospheric Chemistry.

Elucidating isotope exchange between atmospheric trace molecular species is important for environment monitoring, climate control studies, and a fundamental understanding of atmospheric chemistry. Here, we provide direct experimental evidence of oxygen-isotopic exchange between carbon dioxide (CO) and nitrogen dioxide (NO), which are simultaneously emitted into the atmosphere from common sources. A combined near-infrared and UV-vis optical cavity-enhanced experimental investigation along with quantum-chemical calculations followed by a reaction modeling study revealed that CO and NO can communicate isotopically by near-ultraviolet-driven NO photolysis.

Anomalous scattering of polystyrene microparticles revealed by evanescent wave coupled cavity ringdown spectroscopy.

Forward scattering is an essential tool for investigating the colloidal suspension of polystyrene microspheres (PSMs). Evanescent wave coupled cavity ringdown spectroscopy (EW-CRDS) shows the anomalous extinction behavior in the limit of PSM particles that is much larger than the wavelength. EW-CRDS is a highly sensitive technique that improves weak absorption signals by enhancing the absorption path length, allowing for probing a range of processes at the solid/liquid interface by assessing the extinction properties.