Simulation chamber investigation of the reactions of ozone with short‐chained alkenes

Abstract

[1] Reaction rate coefficients and product yields in the gas phase reaction of O 3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined by Simulation of Atmospheric Photochemistry in a Large Reaction Chamber (SAPHIR). In a first set of experiments, reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration time profiles of ozone and the alkenes with side reactions being suppressed by adding a radical scavenger. The rate coefficients obtained agree well with literature data; for all but one alkene, the deviation was less than 10%. In a second set of experiments, OH yields were derived from the additional alkene turnover in the absence of a radical scavenger. In contrast to other studies, the OH yields determined in the dry chamber (propene, 0.10 ± 0.07; 1-butene, 0.00 ± 0.08, isobutene, 0.30 ± 0.14; (Z)-butene, 0.18 ± 0.09; and (E)-butene, 0.70 ± 0.12) differed from the yields obtained under humid conditions (propene, 0.30 ± 0.08; 1-butene, 0.30 ± 0.09; isobutene, 0.80 ± 0.10; (Z)-butene, 0.40 ± 0.05; and (E)-butene, 0.60 ± 0.12). The only exception was ethene ozonolysis, where no OH production was observed. HO 2 yields (propene, 1.50 ± 0.75; 1-butene, 1.60 ± 0.80; and isobutene, 2.00 ± 1.00) estimated from the additional ozone turnover compared to the experiments where radicals were not scavenged are reported here for the first time. Furthermore, the yields of the stable ozonolysis products CO, acetaldehyde, and formaldehyde were acquired by monitoring the concentration time profile of the respective compound.

Technical Note: Formal blind intercomparison of HO<sub>2</sub> measurements in the atmosphere simulation chamber SAPHIR during the HOxComp campaign

“…The chamber is in operation since 2001 and has been described in more detail elsewhere (e.g. Bohn et al, 2005;Rohrer et al, 2005;Wegener et al, 2007). The chamber was successfully used in a number of intercomparison experiments.…”

Investigation of the formaldehyde differential absorption cross section at high and low spectral resolution in the simulation chamber SAPHIR

“…Rohrer et al, 2005;Bossmeyer et al, 2006;Wegener et al, 2007). The chamber consists of double-walled FEP foil (DuPont).…”

“…O 3 is measured by an instrument based on absolute UV absorption at 254 nm (Ansyco). Hydrocarbons are detected by a gas chromatograph (Chrompack) which is described in detail by Wegener et al (2007). The system is equipped with a flame ionisation detector (FID).…”

Intercomparison of peroxy radical measurements obtained at atmospheric conditions by laser-induced fluorescence and electron spin resonance spectroscopy

“…Detailed descriptions, focussing on particular experiments in SAPHIR, were given in the papers by Bohn and Zilken (2005), Rohrer et al (2005), and Wegener et al (2007). Therefore, only a short description is given here.…”

“…The ozonolysis involves a complex system of chemical reactions, which yield various products (Grosjean et al, 1996;Grosjean and Grosjean, 1997;Olzman et al, 1997;Hasson et al, 2001;Wegener et al, 2007). In the first step, ozone is cycloadded to the alkene and forms an ozonide, which rapidly decomposes to either formaldehyde or propanal and a corresponding excited Criegee intermediate, C 2 H 5 CHOO * or HCHOO * , respectively.…”