Incoherent broadband cavity-enhanced absorption spectroscopy in the near-ultraviolet: application to HONO and NO2.

The first application of incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) in the near-ultraviolet for the simultaneous detection of two key atmospheric trace species, HONO and NO2, is reported. For both compounds the absorption is measured between 360 and 380 nm with a compact cavity-enhanced spectrometer employing a high power light-emitting diode. Detection limits of approximately 4 ppbv for HONO and approximately 14 ppbv for NO2 are reported for a static gas cell setup using a 20 s acquisition time. Based on an acquisition time of 10 min and an optical cavity length of 4.5 m detection limits of approximately 0.13 ppbv and approximately 0.38 ppbv were found for HONO and NO2 in a 4 m3 atmospheric simulation chamber, demonstrating the usefulness of this approach for in situ monitoring of these important species in laboratory studies or field campaigns.