OH Radical Detection Using Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS) in an Open-Path Configuration

Hydroxyl radical (OH) is a pivotal oxidant in the atmosphere, exerting significant influence on atmospheric chemistry and participating in diverse environmental processes. However, accurately measuring OH in the atmosphere is challenging due to its short half-life and low ambient concentrations. Various methods, such as laser-induced fluorescence coupled with fluorescence assay by gas expansion (LIF-FAGE), differential optical absorption spectroscopy (DOAS), and ion-chemical ionization mass spectrometry (CIMS), have been employed for OH quantification, each with its associated complexities and limitations.

This study introduces a novel measurement approach utilizing broadband cavity-enhanced absorption spectroscopy (BBCEAS) for detecting OH under ambient atmospheric conditions. The BBCEAS instrument, known for its portability and resilience to interferants owing to its spectroscopic nature, emerges as a practical solution for field measurements. The instrument's characterization involved detecting OH in an open flame, and subsequent enhancements were implemented to render it field-ready, enabling it to compete with established methods like LIF-FAGE, CIMS, and DOAS.

The application of BBCEAS in OH detection represents a valuable tool for atmospheric researchers, offering a balance between portability and sensitivity. This study highlights the potential of BBCEAS as a reliable method for field measurements of OH concentrations, contributing to a more comprehensive understanding of atmospheric processes and chemical reactions.