A study of the ethene-ozone reaction with photoelectron spectroscopy: measurement of product branching ratios and atmospheric implications

Abstract

The ozone-ethene reaction has been investigated at low pressure in a flow-tube interfaced to a u.v. photoelectron spectrometer. Photoelectron spectra recorded as a function of reaction time have been used to estimate partial pressures of the reagents and products, using photoionization cross-sections for selected photoelectron bands of the reagents and products, which have been measured separately. Product yields compare favourably with results of other studies, and the production of oxygen and acetaldehyde have been measured as a function of time for the first time. A reaction scheme developed for the ozone-ethene reaction has been used to simulate the reagents and products as a function of time. The results obtained are in good agreement with the experimental measurements. For each of the observed products, the simulations allow the main reaction (or reactions) for production of that product to be established. The product yields have been used in a global model to estimate their global annual emissions in the atmosphere. Of particular interest are the calculated global annual emissions of formaldehyde (0.96 ± 0.10 Tg) and formic acid, (0.05 ± 0.01 Tg) which are estimated as 0.04% and 0.7% of the total annual emission respectively.

Mass-Resolved Isomer-Selective Chemical Analysis with Imaging Photoelectron Photoion Coincidence Spectroscopy

“…This difference aids PES in the identification of each neutral molecule in a mixture. 8 However, with a few exceptions, 9,10 PES is rarely used to quantitatively analyze mixtures of neutral molecules because there is no unique way to correlate a given electron with the neutral that produced it if only electrons are detected. In contrast with PES, PEPICO spectroscopy extracts both the photoelectron and the photoion from the ionization region.…”

A study of the alkene–ozone reactions, 2,3-dimethyl 2-butene + O3 and 2-methyl propene + O3, with photoelectron spectroscopy: measurement of product branching ratios and atmospheric implications

“…photoelectron spectroscopy and the product branching ratios were measured for all the main products. 1 This present study extends this work by studying the reaction of O 3 with 2,3-dimethyl-2-butene (DMB) and O 3 with 2-methyl propene (2MP).…”

“…(i) Photoelectron (PE) spectra recorded as a function of time PE spectra were recorded for the reactions of O 3 with DMB and O 3 with 2MP at low pressure (E1-2 torr) at different reaction times using a flow-tube attached to the ionization chamber of a PE spectrometer. The procedure used followed that adopted for the reaction of O 3 with ethene, 1 with the main difference being that because the reactions of O 3 with DMB and O 3 with 2MP are faster than the reaction of O 3 with ethene, the glass flow-tube used was shorter. (Rate coefficients at 298 K for reactions of O 3 with DMB and O 3 with 2MP are 1.13 Â 10 À15 and 1.13 Â 10 À17 cm 3 molecule À1 s À1 respectively 4 ).…”

“…These reactions produce OH radicals and results of modelling calculations indicate that they may be important sources of HO x species in the troposphere. [1][2][3] Their atmospheric importance has led to a significant number of experimental studies of their kinetics and mechanisms. 1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17] Rate coefficients and products have been determined for a number of ozone-alkene reactions.…”

“…[1][2][3] Their atmospheric importance has led to a significant number of experimental studies of their kinetics and mechanisms. 1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17] Rate coefficients and products have been determined for a number of ozone-alkene reactions. However, while in general room temperature rate coefficients are well established, there are uncertainties concerning product branching ratios.…”