The Theory of assembly and optical properties of electromagnetic tuneable plasmonic metamaterials

Lead Research Organisation: Imperial College London
Department Name: Dept of Chemistry

Abstract

The ultimate aim of this project is to combine the theory of electro-magneto tunable self-assembly with the theory of plasmonic metamaterials to produce materials with highly tailored optical properties. The project will elaborate and improve on current models of self-assembly of magnetic ellipsoidal particles at fluid interfaces for enhanced prediction of the behaviour of self-assembled systems. This theory will be extended into studying the optical properties of self-assembled plasmonic nanoparticles as metamaterials. The result should yield novel plasmonic nanostructures giving rise to artificial magnetism achieving extraordinary optical properties.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509486/1 01/10/2016 30/09/2021
1829091 Studentship EP/N509486/1 01/10/2016 30/09/2019 Oliver Robotham
 
Description The scope of the project initially was to provide a theoretical grounding for the self-assembly of charged nanoparticles (NPs) at the interface of two immiscible electrolytic solutions (ITIES) and therefore a way to tailor the optical properties of metamaterials (interfacially self-assembled nanoparticle-consisting materials with extraordinary optical properties). We began to explore the properties of the electrolyte-electrolyte interface of 1,2-dichloroethane (DCE) and water, a typical electrolyte system used in optical metamaterial research. Whilst looking into this we started to see that when the type of salt that could be dissolved in DCE such as tetrabutylammonium tetraphenylborate (TBA TPB) was added, it had an affinity for the ITIES unlike the small and polar salts typically dissolved in water such as sodium chloride. This free energy trap for the TBATPB is non-neglible (1-2 kT dependent on the ionic radius) and has a significant impact on the electrochemistry and differential capacitance measured. Additionally, due to the higher concentration of salt at the interface, a charged NP trapped at the interface would experience a greater charge screening and therefore reduced NP-NP repulsion associated with the like-charges on the particles. This work is aimed at providing a heightened awareness of the behaviour of salt at the interface in experiments of these self-assembled systems (which electrolyte concentration corresponds to which salt concentration at the liquid-liquid interface), therefore improving control of salt concentration and NP-NP screening at liquid-liquid interfaces.
Exploitation Route We have helped experimentalists working on these systems acquire a heightened awareness of the non-homogeneous salt concentrations at liquid-liquid interfaces varying with the ionic radii of the ions. We have analysed electrolytes in this work and their specific adsorption at liquid-liquid interfaces measuring the differential capacitance at dilute and high concentrations with supporting theory. However, the ultimate application for the future is for plasmonic nanoparticles (NPs) (nanoparticles reactive to light with optical applications) assembled at liquid-liquid interfaces. The morphology of these particle arrays at liquid-liquid interfaces can change the nature of their interaction with light and therefore, they have highly versatile optical properties. Tailoring the balance of forces of charged NPs (electrostatics, Van der Waals and otherwise) at liquid-liquid interfaces will have impact on their morphology. The scope of this work has been to investigate the electrostatics and therefore the effect of the electrolyte and the interface to the behaviour of charge in systems of immiscible electrolytes. However, further work could see a new theory for the other forces at play for these NP arrays and therefore, extend the work into a general theory for forces associated with charged particles at liquid-liquid interfaces.
Sectors Aerospace, Defence and Marine,Chemicals,Electronics

 
Title GROMACS 
Description GROMACS is a molecular dynamics package that can be used with additional GPU acceleration to calculate physical properties of many different types of system. 
Type Of Technology Software 
Year Produced 2016 
Open Source License? Yes  
Impact All computational findings were performed using the GROMACS package. 
URL https://pubs.rsc.org/en/content/articlehtml/2018/cp/c8cp04924f