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Atmospheric Chemistry: HIRAC Group

The Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC) is a NERC funded atmospheric simulation chamber developed to bridge the divide between the study of elementary reactions in the lab, and large scale field work. Unlike any other atmospheric simulation chambers HIRAC allows researchers the unique ability to control temperature, pressure and photolysis rates during experiments.

Just as the name suggests, HIRAC has a broad range of instrumentation based on different detection techniques so that we can accurately monitor the chemistry occurring inside the chamber. HIRAC has been funded to carry out a number of exciting and novel experiments to answer some of the important questions remaining in atmospheric chemistry. We also plan to use the chamber to test and develop field measurement techniques.

HIRAC is a member of the EUROCHAMP (Integration of European Simulation Chambers for Investigating Atmospheric Processes) network of European chambers.


Gas Kinetics Symposium, July 2016

HIRAC was well represented at the GK symposium held in York with posters on OH reactivity/butanol oxidation (Charlotte), ether oxidation (Diogo and Iusti), isoprene oxidation (Iusti) and CH3O2 detection (Lavinia and Alex).


Reactivity Publication, June 2016

A paper on the development of the OH reactivity instrument has been published in AMT. Charlotte Brumby worked on coupling HIRAC and the reactivity instrument and has more recently been looking at the changes in OH reactivity during butanol oxidation.

CH3O2 Detection, Spring 2016

Using techniques analogous to those for HO2 detection in FAGE, we have measured CH3O2 in HIRAC by conversion of CH3O2 to CH3O and detection of the latter by LIF. We can obtain good kinetics (see figure) and the detection limits may allow for the technique to be deployed in the field. 

CH3O2 recombination decay in HIRAC

CH3C(O)O2 + HO2 publication

Early in 2016 our definitive publication on the OH yields from the above reaction was published in ACP. Carried out in conjunction with Terry Dillon (MPI Mainz and University of York) and Matt Evans (University of York), this study provides the first simulaneous observations of all the product channels from this reaction which can contribute to OH recycling.

New PhD Student

Alex Brennan joins the group to work on CH3O2 detection. Supervised by Dwayne and Paul, and working with Lavinia, Alex will be developing the CH3O2 detection and working with Rob on implementing ROx-LIF detection in HIRAC. 

New dedicated laser

Thanks to investment from the School of Chemistry and the University, we have just received delivery of a new higher powered laser dedicated to HIRAC. This should significantly increase the productivity of HIRAC and the sensitivity of the HIRAC FAGE instrument. The laser provides sufficient power such that the excess can be used for the OH reactivity instrument and to light the department....

International Symposium on Gas Kinetics and Related Phenomena, Szeged, July 2014

Four posters from the HIRAC group were presented and well received at the recent gas kinetics conference in Szeged, Hungary, covering instrument development, mechanistic studies on isoprene oxidation and RO2 chemistry, and on relative rate kinetics studies. Copies of the posters can be found in the poster section.  



HIRAC Group, Prof. Paul Seakins
Address: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT
Telephone:(+44) 0113 343 6543

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