Dr. Stephanie Jones completed her PhD whilst based at the CLF while co-supervised by Andy Ward (CLF) and Martin King. Now, she has recently had her work on atmospheric aerosols accepted for publication in The Journal of Physical Chemistry (J. Phys Chem. A.).
The research, conducted at both the ISIS Neutron and Muon source at RAL and the Institut Laue Langevin, investigated how molecules decay on a water surface. The team consisted of Stephanie, Martin King, Adrien Rennie, Andy Ward, Richard Campbell, and Arwel Hughes.
The degradation of a thin film of molecules on a water surface can be monitored over time by neutron reflectometry. This is where a highly collimated beam of neutrons is fired at a flat surface and the intensity of the beam reflected can be recorded alongside the angle it is fired at or the neutron wavelength. This lets scientists like Stephanie determine variables such as the density and thickness of the surface molecules they are investigating. Firing neutron beams over a set period will show how the thin film changes and decays with time, which can be used to determine how differing molecules and surfaces react with one another to speed up or slow this decay. This could have applications in atmospheric and environmental research – for example, Stephanie and the team’s investigation considered a thin film on an aerosol in the atmosphere. It would require several radical reactions to break down this film, which would therefore take longer than typically expected. This may help us to understand the role of such aerosols in our atmosphere and how they affect the usual breakdown of substances.
Diagram of the degradation of a thin film of molecules on a water surface.
Stephanie completed her PhD with the Central Laser Facility in multiple disciplines - one of her projects included setting up the laser trapping kit at Diamond Light Source. This equipment uses a highly focused laser to move microscopic objects (such as particles or droplets) and place them where desired, as if we were holding them with tweezers. Using a similar concept, she also published research that explored the refractive properties of solid polystyrene aerosols via Mie scattering. This is a type of electromagnetic wave scattering that occurs in the lower part of the atmosphere due to an abundance of approximately spherical particles such as aerosols. The experiment established that optical trapping and Mie scattering could be used to determine the size of the particles and their refractive index, and found there was a large amount of variation between particles which should considered in future investigations.
Since her PhD at the CLF, Stephanie pursued a post-doctoral position at the University of Victoria in Canada, where she researched the nanoplasmonic trapping of proteins. This is a different type of trapping mechanism that uses optical frequencies to hold an object in position. She then moved back to the UK to work as a Product Manager for Laser Quantum before returning to her academic study at the University of Toronto. Here she looked at both photochemically induced processes occurring on indoor surfaces and processes in levitated droplets for atmospheric research. She now works at the Institute of Meteorology and Climate Research in their Atmospheric Aerosol Research Department at the Karlsruhe Institute of Technology in Germany.
Currently, Stephanie is researching microphysical and optical properties of brown carbon aerosol through a method known as electrodynamic levitation. This is where particles are charged and held in place via electric fields, which means they do not need to be touched. Her work also uses cloud chambers to simulate atmospheric conditions, where she investigates aerosol formation and aerosol processing while measuring their properties. This helps Stephanie and other scientists to understand some of the phenomena we observe in the skies around us, inclduing cloud formation. This year she also obtained beamtime at ISIS and completed her first neutron reflection experiment as a Principal Investigator, exploring the oxidation of organosulfate monolayers at the air-water interface.
Octopus facility researcher Andy Ward, who collaborated with Stephanie on this project as well as co-supervising her PhD at CLF, said “It’s great to see Steph is still interested in Climate Research and her time at RAL shows how powerful the use of photons and neutrons can be to understand a challenging problem”.