Dynamic studies of the linear optical properties of nanostructured media

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The development, growth and future of our national economy will become increasingly dependent on scientific innovations in areas that are beyond the cutting edge of current technological capabilities. Nanotechnology is one such area that is already receiving a great deal of input internationally and in the UK, in terms of both scientific effort and financial investment. Advances in technological capability that include modern fabrication techniques and novel approaches to self-assembly of nanostructures, as well as advances in structural characterisation and theoretical understanding, are now stimulating a clear resurgence of interest in the individual and collective behaviour of near atomic-scale, man-made, structures that exhibit new and exciting physical properties.This particular proposal is concerned with the optical properties of nanostructured media in the form two-dimensional arrays of particles that, may or may not, lie within a more complicated multilayered thin film structure. The research team will fabricate 2D arrays of noble metal nanorods by a process of self-assembly that involve, industrially compatible, thin film processing techniques combined with electrochemical, anodisation and deposition, methods for the creation of structured matter on the nanoscale.The processes will be monitored using a variety of optical techniques including dynamic, real-time ellipsometry and photometry over a wide spectral range. These will be complemented by comprehensive post-fabrication processing and additional optical measurements in an attempt to gather a comprehensive set of observations of their anisotropic behaviour.In order to understand the optical data the team will build upon effective medium theories to explain observed behaviour. This will be done by invoking a discrete dipole approach (DDA) to deal with the response of individual nano-particles and their interactions with each other on the microscopic scale. The DDA approach treats each particle as an assembly of equivalent giant atoms that model the properties of odd-shaped media, subject to the limitations of available computing power.The objectives will be to develop the fabrication techniques, with the aim of generating new media; and observe and understand their collective anisotropic, optical behaviour in theoretical terms by extending or developing new 'atomistic-based' mathematical models.