Investigating the “Near-Field” Effects on Mie Scattering in Aerosols: Is there really a near-field effect? CASE project with the Laser Science Facility

Investigating the “Near-Field” Effects on Mie Scattering in Aerosols: Is there really a near-field effect? CASE project with the Laser Science Facility

Project Description

Supervisors

Professor Martin King, Royal Holloway, University of London

Dr Rebecca Fisher, Earth Sciences, Royal Holloway, University of London

 

Scientific Background

Atmospheric aerosols are key players in Earth’s climate system, affecting both radiative balance and air quality. They scatter and absorb solar radiation and act as cloud condensation nuclei, influencing weather and climate dynamics. However, due to their heterogeneous chemical makeup and varied physical properties, predicting their optical behavior is challenging.

A major unresolved question in aerosol science is the interaction between particles in close proximity—specifically, the “near-field” effect (at distances of ~2r). Theorized for decades, especially regarding black carbon near water droplets, this effect could alter light absorption and scattering. Yet, no experiment has conclusively observed it under atmospheric conditions. This PhD project aims to fill that gap by experimentally investigating near-field interactions and validating findings through computational models.

 

Key Research Questions

  • Can optical trapping be used to study interactions between two Mie scatterers?
  • Does proximity affect the scattering intensity of a second particle?
  • How do experimental results compare with predictions from ADDA and T-matrix models?

 

Proposed Work

Using advanced optical trapping, this research will manipulate two solid particles (e.g., silica or polystyrene) within a shared focal plane. One trap remains stationary while the other is moved to probe near-field effects. A counter-propagating laser setup will be used to create stable multi-particle traps, with precise control via acousto-optic devices. Scattering spectra will be recorded using a CCD detector and compared with Mie theory predictions via ADDA and T-matrix simulations.

 

Skills and Methodology

The PhD candidate will gain expertise in:

  • Optical trapping and multi-trap manipulation
  • Mie scattering theory and experimental validation
  • High-resolution optical systems (LEDs, CCDs, diffraction gratings)
  • Data analysis, programming, and computational modeling

 

Why Apply?

This is a unique opportunity to address a long-standing question in aerosol science with cutting-edge tools. Based at the Rutherford Appleton Laboratory, you’ll join a world-class research environment alongside other laser science PhDs. The project offers the chance to publish in high-impact journals and build a strong foundation in both experimental and theoretical physics. If you’re passionate about atmospheric research and optical science, apply now to be part of this groundbreaking work.

Acceptable first degree subjects: Physics, Chemistry, Maths, Engineering or similar subjects

 

Project code: KING_RHUL_ARIES26_CASE

All ARIES CASE studentships include a three to 18-month placement with the non-academic CASE partner during their period of study. The placement offers experience designed to enhance professional development.

References

  • Barker, C. R., King, M. D., & Ward, A. D. (2024). Separation-Dependent Near-Field Effects in Mie Scattering Spectra of Two Optically Trapped Aerosol Droplets. Optics Express, 32(12), 21042-21060. https://doi.org/10.1364/OE.520251
  • Shepherd, R., King, M., Ward, A., Stuckey, E., Welbourn, R., Brough, N., Milsom, A., Pfrang, C., & Arnold, T. (2025). The lifetimes and potential change in planetary albedo owing to the oxidation of thin surfactant organic films extracted from atmospheric aerosol by hydroxyl (OH) radicals at the air–water interface of particles. Atmospheric Chemistry and Physics, 25(4), 2569-2588. https://doi.org/10.5194/acp-25-2569-2025
  • Barker, C., Poole, M., Wilkinson, M., Morison, J., Wilson, A., Little, G., Stuckey, E., Welbourn, R., Ward, A., & King, M. (2023). Ultraviolet refractive index values of organic aerosol extracted from deciduous forestry, urban and marine environments. Environmental Science: Atmospheres, 3(6), 1008-1024. Advance online publication. https://doi.org/10.1039/D3EA00005B, https://doi.org/10.1039/d3ea00005b
  • McGrory, M., Shepherd, R., King, M., Davidson, N., Pope, F., Watson, I. M., Grainger, R., Jones, A., & Ward, A. (2022). Mie scattering from optically levitated mixed sulfuric acid-silica core- shell aerosols: confirmation of core-shell morphology for atmospheric science. Physical Chemistry Chemical Physics, 24, 5813-5822. https://doi.org/10.1039/d1cp04068e
  • Jones, S., King, M., Ward, A., Rennie, A. R., Jones, A., & Arnold, T. (2017). Are organic films from atmospheric aerosol and sea water inert to oxidation by ozone at the air-water interface? Atmospheric Environment, 161, 274-287. https://doi.org/10.1016/j.atmosenv.2017.04.025

Key Information

  • This studentship has been shortlisted for funding under the UKRI NERC DLA funding scheme and will commence on 1 October 2026. The closing date for applications is 23:59 on 7 January 2026.
  • Successful candidates who meet UKRI’s eligibility criteria will be awarded a fully-funded studentship, which covers fees, maintenance stipend (£20,780 p.a. for 2025/26) and a research training and support grant (RTSG). A limited number of studentships are available for international applicants, with the difference between 'home' and 'international' fees being waived by the registering university. Please note, however, that ARIES funding does not cover additional costs associated with relocation to, and living in, the UK, such as visa costs or the health surcharge.
  • ARIES postgraduate researchers (PGRs) benefit from bespoke training and ARIES provides £2,500 to every student for access to external training, travel and conferences, on top of all Research Costs associated with the project. Excellent applicants from quantitative disciplines with limited experience in environmental sciences may be considered for an additional 3-month stipend to take advanced-level courses. Excellent applicants from quantitative disciplines with limited experience in environmental sciences may be considered for an additional 3-month stipend to take advanced-level courses.
  • ARIES is committed to equality, diversity, widening participation and inclusion in all areas of its operation. We encourage enquiries and applications from all sections of the community regardless of gender, ethnicity, disability, age, sexual orientation and transgender status. Academic qualifications are considered alongside non-academic experience, and our recruitment process considers potential with the same weighting as past experience.
  • All ARIES studentships may be undertaken on a part-time or full-time basis. International applicants should check whether there are any conditions of visa or immigration permission that preclude part-time study. All advertised project proposals have been developed with consideration of a safe, inclusive and appropriate research and fieldwork environment with respect to protected characteristics. If you have any concerns, please contact us.
  • For further information, please contact the supervisor. To apply for this Studentship, follow the instructions at the bottom of the page or click the 'apply now' link.
  • ARIES is required by our funders to collect Equality and Diversity Information from all of our applicants. The information you provide will be used solely for monitoring and statistical purposes; it will remain confidential and will be stored on the UEA SharePoint server. Data will not be shared with those involved in making decisions on the award of Studentships and will have no influence on the success of your application. It will only be shared outside of this group in an anonymised and aggregated form. You will be asked to complete the form by the University to which you apply.
  • ARIES studentships are subject to UKRI terms and conditions. Postgraduate Researchers are expected to live within reasonable distance of their host organisation for the duration of their studentship. Please see https://www.ukri.org/publications/terms-and-conditions-for-training-funding/ for more information.

Apply Now

Apply now via the  Royal Holloway Application Portal