Christian Pfrang

  • Associate Professor/Senior Lecturer in Atmospheric Science - University of Birmingham

Research interests

Dr Pfrang has > 20-yr experience in laboratory-based atmospheric science with core expertise in chemical kinetics of reactions in the gas-phase, in levitated droplets & self-assembled nanomaterials. He led research at large-scale facilities (> 45 access grants; 2 facility-based PhD studentships) and has experience with kinetic model development as Visiting Scientist at the Max Planck Institute for Chemistry (MPIC) since 2008.  He developed in-situ nitrate radicals generation methods and a mobile Raman acoustic levitator for atmospheric studies that was recently linked to structural investigations by X-ray scattering.

Current Key Research Strands

  • Indoor Air Quality (funded by NERC’s Clean Air Strategic Priorities Fund (SPF))

The general population stays ca. 90% of time indoors with a trend in the UK towards increasing periods spent inside. Vulnerable Groups (VGs) including children and people with pre-existing medical conditions remain indoors for even longer periods. Yet, the air inside children’s rooms, particularly at disadvantaged homes, can be five times more polluted than outside air. VGs are also most susceptible to Air Pollution (AP); this motivated the interdisciplinary NERC network (one of the 6 UK networks funded by the Clean Air Strategic Priorities Fund (SPF)) “Air Pollution Solutions for Vulnerable Groups (CleanAir4V)” Dr Pfrang is leading (global-PI) focussing on the air quality experience of vulnerable groups including project partner Dr Wilke from BAM with key expertise on indoor air quality together with 21 further national and international project partners from academia, industry, local government and other stakeholders (£621k; funded for three years from Sept 2020). Through this network it became clear that low-cost sensors are a key element to establish and enhance the air pollution experience of vulnerable people and Dr Pfrang has recently started to explore routes to test and develop those sensors (e.g. IGI Pump Priming grant with Jason Zhang in Chemical Engineering developing novel QCM-based low cost sensors).

  • Studying Levitated Atmospheric Aerosols (funded by NERC, Royal Society, Diamond Light Source (DLS), MAXIV Laboratory & Rutherford Appleton Laboratory)

The main objective is to improve the understanding of the impact of chemical ageing of atmospheric aerosols on cloud formation, radiative forcing and, ultimately, climate change.  Dr Pfrang applies the technique of acoustic levitation to atmospheric sciences by studying model systems representative of atmospheric processes; their physical & chemical modifications in varying conditions is being monitored to obtain insight into the behaviour of atmospheric particles.  Our droplet levitator and related levitation systems are being interfaced with complementary analytical techniques such as Raman microscopy or Small Angle X-ray Scattering (SAXS).  Recently, we also started to carry out directly related work on thin films to screen a wider range of conditions more rapidly.

Highlight papers: Milsom et al., Faraday Discussions, 2020; Pfrang et al., Nature Communications, 2017; Seddon et al., Journal of Physical Chemistry Letters, 2016; King et al., Faraday Discussions, 2008.

  • Studying the Atmospheric Ageing of One-Molecule Thin Organic Layers at the Air–Water Interface (funded by NERC, Institut Laue Langevin (ILL) & ISIS Neutron Source)

We investigate of the behaviour of organic monolayers floating on an aqueous subphase to understand the kinetic behaviour and stability of organic surfactant films at the interface of aerosol droplets using neutron reflectometry combined with complementary techniques such as infra-red reflection absorption spectroscopy (IRRAS), Brewster-angle microscopy and ellipsometry.

Highlight papers: Woden et al., Atmospheric Chemistry and Physics, 2020; Woden et al., Atmosphere, 2018; Sebastiani et al., Atmospheric Chemistry and Physics, 2018; Skoda et al., RSC Advances, 2017; Pfrang et al., Physical Chemistry Chemical Physics, 2014.

  • Kinetic Modelling of the Behaviour of Atmospheric Aerosols (funded by NERC & Royal Society)

Our experimental work on atmospheric aerosols is complemented by modelling studies in collaboration with the Max Planck Institute for Chemistry (MPIC) to (i) choose most insightful experimental conditions; (ii) develop realistic, yet efficient parameterisation of experimental findings; and (iii) implement –in the medium term– these new parameterisations in powerful atmospheric modelling frameworks.  Modelling approaches co-developed by Dr Pfrang (in particular KM–SUB and KM–GAP) are widely used in the aerosol community and have been employed in 50+ research projects across the world (> 370 citations).

Highlight papers: Pfrang et al., Atmospheric Chemistry and Physics, 2011; Shiraiwa, Pfrang et al., Atmospheric Chemistry and Physics, 2012; Pfrang et al., Atmospheric Chemistry and Physics, 2010; Shiraiwa, Pfrang & Pöschl, Atmospheric Chemistry and Physics, 2010 (also Sebastiani et al., Atmospheric Chemistry and Physics, 2018).

  • Kinetics and Products of Atmospherically Relevant Gas-phase Reactions (funded by NERC)

We have expertise in studying gas-phase reactions of low volatility organic compounds with ozone and nitrate radicals by experimental and computational methods.  This expertise was a key driver to get involved in a current NERC Responsive Mode grant (Degradation of Odour signals by air pollution: chemical Mechanisms, plume dynamics and INsect-Orientation behaviour (DOMINO); see below) applying these methods to understanding the impact of air pollution on insect orientation and ultimately pollination.

Highlight papers: Pfrang et al., Atmospheric Environment, 2008; Stewart et al., Atmospheric Environment, 2013; Pfrang et al., Atmospheric Environment, 2006; Pfrang et al., Physical Chemistry Chemical Physics, 2006

  • Investigating the Impact of Plants on Indoor Air Quality: a Multi-scale Cross-disciplinary Approach (funded by EPSRC & Royal Horticultural Society (RHS))

In Britain, residents tend to spend as much as 90% of their time indoors, where poor indoor air quality can result in the prevalence of Sick Building Syndrome.  Plants offer easy access, low-cost and versatile options to substantially improve indoor air quality.  This cross-disciplinary project jointly funded by EPSRC and the Royal Horticultural Society (RHS) scrutinises the potential of a range of plant species in different growth media to provide key air quality services by removing harmful gases (in particular CO2 and NO2) and particles present indoors.

Highlight papers: Gubb et al., Air Quality, Atmosphere & Health, 2018 & Gubb et al., Air Quality, Atmosphere & Health, 2019; Gubb et al., Building Services Engineering Research & Technology, 2020.

  • Degradation of Odour signals by air pollution: chemical Mechanisms, plume dynamics and INsect-Orientation behaviour (DOMINO) (funded by NERC)

This NERC Discovery Science project investigated the mechanisms by which air pollution can disrupt vital airborne chemical signals that insects use for critical processes, such as mating or finding a flower, and will evaluate the ecological consequences of this phenomenon (lead PI: Dr Girling, University of Reading; further Co-Is: Drs Nemitz and Langford, Centre for Ecology & Hydrology (CEH), Edinburgh; Dr Birkett, Rothamsted Research).  Dr Pfrang co-designed this cross-disciplinary research project with Dr Girling as an exceptionally active Co-I supporting Dr Girling to get his first NERC grant; Dr Pfrang was PI for a 24-month Chemistry PDRA studying the fundamental physical chemistry underpinning this research; this work will contribute to a high-impact manuscript bringing together the laboratory-based, wind-tunnel-based and field-based work to be submitted in 2021.

https://www.ceh.ac.uk/our-science/projects/degradation-odour-signals-air-pollution-chemical-mechanisms-plume-dynamics-and

  • Venusian Electricity, Nephology, and Ionisation (VENI): Unravelling the secrets of Venus’ clouds (funded by Science and Technology Facilities Council (STFC))

Clouds of Venus seem likely to be affected by Galactic Cosmic Rays (GCRs), as is seen to occur elsewhere in the solar system such as at Neptune and Uranus.  GCRs are energetic particles born in supernovae and emitted into space.  They are constantly bombarding Earth, and the other planets in the solar system, where they interact with the planetary atmospheres.  The most energetic GCRs cause further ionisation (the creation of charge) via a cascade of interactions in our atmosphere.  This affects our atmosphere in a variety of ways, including allowing current to flow in a Global Electric Circuit (GEC).  In a series of experiments, we will portray the conditions on Venus.  Charging through ionisation around levitated droplets is created and the effects on the droplets are monitored in an electric field.  The findings of this study will help us to determine how important the effects induced by GCRs are on Venus, in particular in the formation and persistence of the clouds.  The atmospheric electricity of Venus is not currently well understood and the results could inform space mission design and planning to minimise hazards to future probes and landers.  It may also help us to find out whether or not there is a GEC on Venus.  VENI provides a means to answer these, and other, important questions about our closest neighbour (lead PI: Professor Giles Harrison, University of Reading).