About the project
The structure of a liquid can change as its molecules or particles aggregate, separate into phases, or coalesce into larger domains. This project will use intense terahertz spectroscopy to track this structural evolution across different length scales, simultaneously probing local molecular motions and scattering from emerging mesoscale structures.
Liquids are rarely as uniform as they appear: their components can reorganise into distinct domains. While local molecular motions occur on sub-picosecond timescales, aggregation can produce droplets, clusters and domains hundreds of micrometres across. These very different spatial and dynamical regimes are usually studied with different techniques, making it difficult to connect microscopic dynamics directly with the emergence of mesoscale structure.
Intense terahertz spectroscopy provides a new way to explore this connection. In strongly absorbing aqueous samples, it can resolve small changes in dielectric response, while our recent work on water-based liquid crystals shows that micrometre-scale domains can generate an additional terahertz loss consistent with scattering. This suggests a route to following structural evolution across scales within one measurement framework.
You will first establish the underlying physics using calibrated particles dispersed in water, varying their size, concentration and dielectric contrast to determine when effective-medium behaviour gives way to measurable scattering. These benchmark systems will provide a quantitative foundation before moving to more complex liquids in which the structure evolves dynamically.
Having established the scattering crossover in controlled suspensions, you will then investigate liquids in which structure evolves over time through aggregation, phase separation or self-assembly. Candidate systems include colloidal dispersions, emulsions undergoing droplet growth and coalescence, and liquid crystals that self-assemble into micrometre-scale domains.
This project offers training across ultrafast optics, terahertz spectroscopy, soft matter, and computational modelling. You will develop both experimental and analytical skills while addressing a fundamental question: how do molecular-scale dynamics connect to the evolution of mesoscale morphology in complex liquids? By exploring whether common terahertz signatures persist across different liquids, the project will establish the physical limits and wider applicability of this approach to studying aggregation and phase separation.
The School of Physics and Astronomy is committed to promoting equality, diversity inclusivity as demonstrated by our Athena SWAN award. We welcome all applicants regardless of their gender, ethnicity, disability, sexual orientation or age, and will give full consideration to applicants seeking flexible working patterns and those who have taken a career break. The University has a generous maternity policy, onsite childcare facilities, and offers a range of benefits to help ensure employees’ well-being and work-life balance. The University of Southampton is committed to sustainability and has been awarded the Platinum EcoAward.
