Laboratory studies of Criegee radical reactions
Lead Research Organisation:
University of Southampton
Department Name: Sch of Chemistry
Abstract
Chemicals entering the atmosphere come from a number of sources, but in broad terms are either from human activity or from the biosphere (natural systems). What happens to these chemicals once in the atmosphere is very important of course. If they are toxic they can impact on the health of humans, animals and natural ecosystems. Therefore, it is vital that we understand how pollutants are removed by the atmosphere. One very important removal process involves the so called hydroxyl radical. This is an extremely reactive species that acts like a chemical detergent, destroying pollutants and cleaning up the atmosphere. It has emerged in recent investigations that an important source of the hydroxyl radical must be coming from Criegee radicals. However, these Criegee radicals have been impossible to measure until recently. Work carried out by us, using a facility in the USA, has allowed us to observe a Criegee radical for the first time. In this project we will develop a state-of-the-art experimental system that will allow us to investigate the chemistry of Criegee radicals and therefore to help us to understand how they affect the amount of hydroxyl radical is present in the atmosphere. Such work will not only improve our understanding of the urban environment but will also have implications for climate studies as well. Reactions of Criegee intermediates, over a wide range of pressure and temperature, are of importance in atmospheric chemistry. The proposed UV-PE apparatus will be the first of its kind and will enable us to carry out a range of experiments to study reactions of these radicals that, as far as we are aware, no one else in the world can do. To demonstrate how versatile the apparatus is we propose a carefully designed set of experiments to look at the source and fate of Criegee radicals in the troposphere. Quantum chemistry calculations of the reactions studied will provide detailed understanding of their mechanisms and the kinetic data will be incorporated into models describing the troposphere and compared with available measurements.
Organisations
People |
ORCID iD |
John Dyke (Principal Investigator) |
Publications
Beccaceci S
(2012)
A study of the atmospherically important reactions of dimethylsulfide (DMS) with I2 and ICl using infrared matrix isolation spectroscopy and electronic structure calculations.
in Physical chemistry chemical physics : PCCP
Chhantyal-Pun R
(2017)
Direct Measurements of Unimolecular and Bimolecular Reaction Kinetics of the Criegee Intermediate (CH3)2COO.
in The journal of physical chemistry. A
Chow R
(2016)
A theoretical study of the atmospherically important radical-radical reaction BrO + HO2; the product channel O2(a1?g) + HOBr is formed with the highest rate.
in Physical chemistry chemical physics : PCCP
Chow R
(2014)
Rate coefficients of the Cl + CH3C(O)OCH3 ? HCl + CH3C(O)OCH2 reaction at different temperatures calculated by transition-state theory with ab initio and density functional theory reaction paths.
in The journal of physical chemistry. A
Copeland G
(2011)
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
in Physical Chemistry Chemical Physics
Copeland G
(2014)
Determination of the photolysis rate coefficient of monochlorodimethyl sulfide (MClDMS) in the atmosphere and its implications for the enhancement of SO2 production from the DMS + Cl2 reaction.
in Environmental science & technology
Dyke J
(2012)
Chemistry for Sustainable Development
Innocenti F
(2013)
Threshold photoelectron spectroscopy of vibrationally excited nitrogen
in Journal of Physics B: Atomic, Molecular and Optical Physics
Khan M
(2016)
A modelling study of the atmospheric chemistry of DMS using the global model, STOCHEM-CRI
in Atmospheric Environment
Lee EP
(2012)
Spectroscopy of the simplest Criegee intermediate CH2OO: simulation of the first bands in its electronic and photoelectron spectra.
in Chemistry (Weinheim an der Bergstrasse, Germany)
Description | Understanding the role of Criegee intermediates in the oxidation chemistry of the atmosphere has been improved |
Exploitation Route | The results can be used by atmospheric modellers to improve predictions of atmospheric chemistry and climate. |
Sectors | Environment |
Description | The results obtained have been used to contribute to an understanding of the oxidising capacity of the atmosphere and climate change. Prof Dyke has spent 5 x 2-week (and 3x2 day) visits to Prof Percival's laboratory in Manchester to develop a Photoelectron Spectrometer to study Criegee intermediates and their reactions. This spectrometer is now nearing completion and the postdoctoral fellow (Dr Bacak) will be taking first data in the next 3 months. |
First Year Of Impact | 2003 |
Sector | Environment |
Impact Types | Policy & public services |
Description | Atmospheric Chemistry, Climate Change and Criegee intermediates |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | A general talk to the Sixth Form at Barton Peveril School Eastleigh, Hampshire under the auspices of the Royal Society of Chemistry(RSC). A lecture of atmospheric chemistry to a sixth form school audience. |
Year(s) Of Engagement Activity | 2013 |