Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene

Abstract

We use a large laboratory, modeling, and field dataset to investigate the isoprene + O3 reaction, with the goal of better understanding the fates of the C1 and C4 Criegee intermediates in the atmosphere.

Measurements of a potential interference with laser-induced fluorescence measurements of ambient OH from the ozonolysis of biogenic alkenes

“…Given that OH yield from the decomposition of excited CIs in the isoprene mechanism is lower than that for the α-pinene mechanism, the absence of a detectable interference in the isoprene experiments described here may suggest that the decomposition of these intermediates inside the FAGE detection cell may also result in a lower OH yield. These results are also consistent with the recent study by Nguyen et al (2016), who found that the majority of SCIs produced in the ozonolysis of isoprene were the simplest SCI, CH 2 OO. The unimolecular reactivity of CH 2 OO is greatly reduced compared to other SCIs due to the fact that it is non-syn, without any facing hydrocarbon groups (Nguyen et al, 2016), and does not lead to OH formation.…”

“…These results are also consistent with the recent study by Nguyen et al (2016), who found that the majority of SCIs produced in the ozonolysis of isoprene were the simplest SCI, CH 2 OO. The unimolecular reactivity of CH 2 OO is greatly reduced compared to other SCIs due to the fact that it is non-syn, without any facing hydrocarbon groups (Nguyen et al, 2016), and does not lead to OH formation. Consistent with the observation that the observed interference appears to be a constant fraction of the total OH yield in these experiments independent of the ozone concentration and the turnover rate (Figs.…”

Assessing the influence of NO<sub><i>x</i></sub> concentrations and relative humidity on secondary organic aerosol yields from <i>α</i>-pinene photo-oxidation through smog chamber experiments and modelling calculations

“…These processes may be related to the vapours' reactive uptake onto walls (Loza et al, 2010;Nguyen et al, 2016) or to their absorptive uptake (Zhang et al, 2014;Nah et al, 2016). The reactive uptake of organic vapours onto chamber walls is only significant at high RH.…”

Non-radioactive Chemical Ionization Mass Spectrometry Using Acetic Acid–Acetate Cluster as a Reagent Ion for the Real-time Measurement of Acids and Hydroperoxides

“…22 Previous studies have suggested that H 2 O 2 is generated from the decomposition of HMHP. 21,22 Although under dry conditions the ion signal at m/z 183 is assigned to [AcOH¢(HO)CH 2 CH 2 OOCH 2 OOH ¹ H] ¹ , the experiments under humid conditions showed an increase in the intensity at m/z 183; therefore, this signal may be ascribed to a different ion produced from a process involving water vapor. The most likely candidate is an adduct of acetic acidacetate and HMHP, namely, [(AcOH) 2 …”

“…Since the molecular weight is the same for HMHP and SO 2 , the former cannot be detected by SO 2 ¢Cl ¹ CIMS; however, it was measured by CF 3 O ¹ CIMS. 21 In addition, the reaction between CH 2 OO and water vapor reportedly produced formic acid, 21 resulting in the observed increase in the peak intensity…”