Impact of ozone and inlet design on the quantification of isoprene-derived organic nitrates by thermal dissociation cavity ring-down spectroscopy (TD-CRDS)

Abstract. We present measurements of isoprene-derived organic nitrates (ISOP-NITs) generated in the reaction isoprene with nitrate radical (NO3) a 1 m3 Teflon chamber. Detection ISOP-NITs is achieved via their thermal dissociation to nitrogen dioxide (NO2), which monitored by cavity ring-down spectroscopy (TD-CRDS). Using inlets (TDIs) made quartz, temperature-dependent profiles (thermograms) measured presence ozone (O3) are broad (350 700 K), contrasts narrower previously observed for, for example, isopropyl (iPN) or peroxy acetyl (PAN) under same conditions. The shape thermograms varied TDI's surface-to-volume ratio and material inlet walls, providing clear evidence that quartz surfaces catalyse unsaturated leading formation NO2 at temperatures well below 475 K, impeding separate detection alkyl (ANs) (PNs). use TDI consisting non-reactive suppresses conversion ANs 473 thus allowing selective PNs. potential interference thermolysis nitric acid (HNO3), nitrous (HONO) O3 assessed.