Development and Application of Cavity-based Absorption Spectroscopy in Atmospheric Chemistry: Recent Progress

Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years. Cavity-based absorption spectroscopy, which uses a high-finesse cavity to achieve very long absorption path-length, thereby achieving ultra-high detection sensitivity, plays an extremely important role in atmospheric chemistry research. Based on the Beer-Lambert law, this technology has the unique advantages of being non-destructive, chemical-free, and highly selective. It does not require any sample preparation and can quantitatively analyze atmospheric trace gases in real time and in situ. In this paper, we review the following: (1) key technological advances in different cavity-based absorption spectroscopy techniques, including cavity ring-down spectroscopy, cavity-enhanced absorption spectroscopy, cavity attenuated phase shift spectroscopy, and their extensions; and (2) applications of these techniques in the detection of atmospheric reactive species, such as total peroxy radical, formaldehyde, and reactive nitrogen (e.g., NOx, HONO, peroxy nitrates, and alkyl nitrates). The review systematically introduces cavity-based absorption spectroscopy techniques and their applications in atmospheric chemistry, which will help promote further communication and cooperation in the fields of laser spectroscopy and atmospheric chemistry.