Atmospheric, Planetary and Theoretical Chemistry
The Atmospheric, Planetary and Theoretical Chemistry (APTC) group hosts one of the largest kinetics groups in the world, underpinning applications in sustainability, energy storage, alternative fuels, air quality, climate change and astrochemistry, and with extensive activities within the National Centre for Atmospheric Science (NCAS). The group has a unique capability and expertise in atmospheric fieldwork, laboratory and theoretical studies of processes, and numerical modelling from the Earth’s surface to the edge of space and astrochemical environments. We are working in emerging areas of renewable fuels, exoplanet discovery, space debris and space weather, plasmas and high-temperature chemistry and the development of methods which can treat large quantum systems. We have strong collaborations across the University via the Priestley Centre for Climate Futures, the Institute for Climate and Atmospheric Science, and the School of Physics and Astronomy, as well as nationally and internationally to foster interdisciplinary research and innovation in atmospheric and planetary chemistry.
We seek to understand the vital resource that is our atmosphere, which is essential for a sustainable future. Amongst other things, atmospheric chemistry influences air quality, human health, and climate change, and hence the future of our planet. Missions to other planets and moons in our solar system are revealing how extraordinarily diverse atmospheres have developed, which in turn helps to understand the evolution of our own atmosphere. Evermore detailed astronomical observations point to the complexity of chemistry in stellar environments, for example using the ALMA array radio-telescope and space-borne JWST infrared telescope.
More than a thousand exoplanets (around other stars in our galaxy) have now been discovered, and we’re starting to be able to detect their atmospheric properties. Unravelling the complexity of the chemistry of an atmosphere requires a range of complementary approaches from lab studies and field observations, through simulations to models. Our work on Earth’s atmosphere is closely aligned with the Natural Environment Research Council’s (NERC) strategic priority research areas which aim to tackle and provide environmental solutions to major challenges of the 21st Century related to climate, sustainability, air pollution and human health.
We’re also developing a strong research programme into chemistry relevant to other planets in the solar system, to newly discovered exoplanets and the regions between stars. Our links to instrument manufacturers, government departments and a wide range of international collaborators are very strong.
Atmospheric chemistry
We apply laboratory measurements, field studies and computer modelling to the study of the Earth’s atmosphere. Research in this area focuses on:
- Field measurements to measure:
- Key species in the atmosphere – e.g. oxidizing radicals such as the hydroxyl radical, OH, using laser-based techniques in environments ranging from the remote marine boundary layer to polluted megacities.
- Metallic species in the mesosphere from satellites and rockets.
- Laboratory studies to understand:
- Fundamentals of reaction kinetics and what controls the temperature and pressure dependence of rate coefficients and product branching ratios
- The chemical oxidation of volatile organic compounds, for example emerging new biofuels and alternate fuels, and how oxidation processes impact on air quality and climate change;
- Heterogeneous chemistry occurring on the surface of atmospheric aerosols and their role on the composition of the atmosphere
- Combustion chemistry of conventional and non-fossil fuels, and the impact combustion has on the atmosphere
- The chemistry of meteor-ablated metals in the upper atmosphere
- Computer Modelling
- Leeds researchers developed the Master Chemical Mechanism for detailed modelling of the tropopshere, and researchers have contributed to the development of whole atmosphere models such as the Whole Atmosphere Community Climate Model (WACCM); comparisons are made with in field measurements using in situ and remote sensing instruments
- Leeds researchers developed the MESMER rate theory kinetics code, developed at Leeds, that enables calculation of rate coefficients and product branching ratios over a very wide range of temperatures and pressures, both for comparison with experiment and to enable extrapolation to conditions of temperature and pressure which are not achievable in the laboratory
Many of these research interests are coordinated through the National Centre for Atmospheric Science, the Institute for Climate and Atmospheric Science (ICAS), and we are a member of the Panorama NERC Doctoral Training Partnership.
Planetary and interstellar chemistry
The conditions of other planetary and lunar atmospheres in our solar system, as well as interstellar environments, are very different from Earth. Although some of the approaches are the same (a combination of laboratory work, observations and computer modelling) several aspects of the work are different:
- Enhanced focus on chemical kinetics at very low temperatures (down to 23 K) using a pulsed Laval expansion, specialised flow tubes and theoretical models such as the kinetics package MESMER
- Our experience in combustion and high temperature pyrolysis chemistry is relevant for the conditions of ‘super Earth’ and ‘hot Jupiter’ exoplanets
- Laboratory studies of the chemistry of the formation of dust and complex organic molecules in interstellar environments
We have strong links with the School of Physics and Astronomy and collaborations with colleagues in the USA at NASA, JPL and many university departments worldwide.
Theoretical Chemistry
- We use Quantum and Classical Molecular dynamics focused on the development of new computational methods to simulate the motion of atoms and molecules and applying them to the dynamics of peptides and proteins, energy redistribution in large molecules, photochemistry and chemistry of plasma. See https://molecular-dynamics.leeds.ac.uk/ for more details.
- Ab initio electronic structure methods are used to calculate the potential energy surfaces for atmospheric and astrochemical reactions. Stationary point energies and optimised geometries are used as input into rate theory calculations, for example using MESMER.
Facilities
- A range of state-of-the-art field measurement instruments, including those to measure radical species using laser-induced fluorescence spectroscopy, and also atmospheric photolysis frequencies, both forming part of the Atmospheric Measurement and Observation Facility within the National Centre for Atmospheric Science
- New instrumentation is being developed for the FAAM Airborne Laboratory as part of its £49 million Mid-Life Upgrade.
- The Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC) for atmospheric simulations
- An aerosol laboratory equipped with an aerosol flow-tube, Potential Aerosol Mass chamber and reactor to study aerosol photochemistry
- Ten interchangeable laser bays which allow the flexible combination of over 20 lasers to a range of apparatus including flow tubes, flash photolysis apparatus, time-of-flight mass spectrometers, and a Laval supersonic nozzle expansion for kinetics studies at temperatures as low as 23 K
- A range of computing facilities including access to the Leeds supercomputer ARC and N8 supercomputer.
Research Group Members
- Dwayne Heard (Head of Section) – Atmospheric chemistry and astrochemistry; field measurements, aerosols and kinetics.
- Dan Marsh – Planetary Atmospheres and Climate
- John Plane – Kinetics, spectroscopy, planetary atmospheres, interstellar chemistry
- Paul Seakins – Reaction kinetics for atmospheric and combustion chemistry
- Dmitry Shalashilin – Quantum and classical molecular dynamics
- Dan Stone – Atmospheric oxidation chemistry and absorption spectroscopy of trace reactive speacis
- Lisa Whalley – Atmosepheric chemistry; field measurements and modelling
- Mark Blitz – Kinetics and photochemistry. experiments and theoryPublications
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PhD projects
We have opportunities for prospective postgraduate researchers including as part of the Panorama NERC Doctoral Training Partnership. Find out more about these opportunities at our research portal.