Nanoparticle-based products are finding an increasing range of applications including anti-cancer therapeutics, medical diagnostics, catalysis and quantum technologies. Accurate characterisation of their properties, dimensional and chemical among others, is required for their development, quality control in manufacture, regulatory compliance and end-of-life management.Available methods for characterising these particles include standard optical techniques to determine one or more of these key properties. Difficulties arise when a given measured optical parameter shows dependence on multiple properties of the particle, for example shape, size and material characteristics. Thus, a priori particle information must often be assumed to increase the accuracy of, for example, particle sizing measurements. The intention of this project is to develop an optical characterisation technique, simultaneously determining multiple geometric and compositional properties of nanoparticles, without the need for a priori measurement or assumptions, Polarimetric methods pose a promising complementary technique to traditional particle sizing methods, presented by way of comparison with traditional reflection ellipsometry. Explorations into this domain exist in literature, however possess a notable absence in application to the full characterisation of homogeneous colloidal suspensions of nanoparticles representative of the above detailed applications. Initial simulations reveal a theoretical upper bound on the provision of unique determination of size characteristics of nanoparticles, which can be understood by deconvolving the Mie scattering formalism into its multipolar contributions. Planned experiments and existing theoretical and experimental results are detailed, with a combined polarimetric and light scattering metrological method justified as excluding the need for a priori particle parameterisation within a theoretical limit.

Matthew Jacobs is a PhD student with the University of Bristol and the National Physical Laboratory. His academic background is in Astrophysics and possesses industrial experience across material development, applied statistics and optical instrument design. Over his career he has been awarded the Keele University, Excellence scholarship, the Institute of Physics Excellence scholarship, a Department for Education award, and other accolades across his speaking and writing. His special interests lie in nanoparticle characterisation and the development of robust metrological techniques spanning a range of complex particle parameters.