Abstract. We report on applications of the ultraviolet-light-emitting-diode-based incoherent broadband cavity-enhanced absorption spectroscopy
(UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and
CH2O in a simulation chamber. Performance intercomparison of
UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a Fourier transform infrared (FTIR)
spectrometer has been carried out on real-time simultaneous measurement of
HONO, NO2 and CH2O concentrations during the reaction of NO2
with H2O vapour in CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber). The 1σ
(signal-to-noise ratio (SNR) = 1) detection limits of 112 pptv for NO2, 56 pptv for HONO and 41 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement.
On the contrary to many set-ups where cavities are installed outside the
simulation chamber, we describe here an original in situ permanent
installation. The intercomparison results demonstrate that IBBCEAS is a very
well suitable technique for in situ simultaneous measurements of multiple
chemically reactive species with high sensitivity and high precision even if
the absorption bands of these species are overlapped. It offers excellent
capacity for non-invasive optical monitoring of chemical reactions without any
perturbation. For the application to simulation chambers, it has the
advantage to provide a spatially integrated measurement across the reactor
and hence to avoid point-sampling-related artefacts.