Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub>, and RONO<sub>2</sub> in the atmosphere

Abstract. We developed thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS) for the in situ measurement of NO2, total peroxy nitrates (PNs, RO2NO2), and alkyl (ANs, RONO2) atmosphere. PNs ANs were thermally converted to NO2 at corresponding pyrolytic temperatures detected by CEAS 435–455 nm. The instrument sampled sequentially from three channels ambient temperature, 453 653 K, with a cycle 3 min, measure NO2+ PNs, + ANs. absorptions between used derive mixing ratios spectral fitting. detection limit (LOD, 1?) retrieving was 97 parts per trillion volume (pptv) 6 s. uncertainty 9 %, while uncertainties PN AN larger than those due chemical interferences that occurred heated channels, such as reaction NO (or NO2) radicals produced organic nitrates. Based on laboratory experiments numerical simulations, we created lookup table method correct these under various nitrates, NO, NO2. Finally, present first field deployment compare it other instruments during campaign China. advantages limitations this are outlined.