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published_or_final_version / abstract / Physics / Master / Master of Philosophy

The importance of the phthalocyanine molecule has generated interest in diverse fields such as thin films, polymer chemistry, liquid crystals, catalysts and numerable electrical, electronic and biological applications together with traditional applications such as dyes and pigments. These laboratories have, to date, concentrated on the synthesis of functionalised phthalocyanine moieties with properties which can be designed for specific applications and, as a result, a battery of materials has been produced at a rate that far exceeded the rate at which the compounds could be fully characterised. The work presented in this thesis is concerned with the study of a range of materials, already available in the group, with a view to providing information on the behavio L'r of Pcs in various molecular assemblies to develop them for specific applications. Chapter 2 is concerned with thin Pc films. The study concentrates on the thermotropic behaviour of some liquid crystalline Pes fonnulated as spin coated, Langmuir-Blodgett, smeared and sublimed films . Chapter 3 contains an account of photochemical stability studies carried out on a series of octaalkyl Pc both in solution and in the solid phase. The role of the central species, substituents and solvent (if applicable) is explored and the results of a series of experiments designed to probe the mechanistic features of the photochemistry are also presented. The development and characterisation of a series of zinc phthalocyanines as potential photosensitisers for use in the photodynamic therapy (PDT) of cancer is covered in chapter 4. The author has carried out photophysical measurements on some octaaJkyl zinc phthalocyanines and comparisons have been made, where appropriate, with other materials currently considered to be promising drug candidates for use in PDT. During the course of this research interesting aggregation and liquid crystal properties were observed for certain zinc and metal-free derivatives. Chapter 5 details how UVVis and IH-NMR. techniques were used to probe these intriguing effects a little further.

published_or_final_version / Physics / Master / Master of Philosophy

No description available.

No description available.

No description available.

No description available.

The properties of surface plasmon polaritons which propagate in optically nonlinear or magnetic media are investigated. Expressions for the electromagnetic fields of a multilayer stack are derived by modification of the Fresnel reflection coefficients. Original research on prism-coupled, nonlinear, long-range surface plasmon polaritons, and on bound and prism-coupled, long-range surface magnetoplasmon polaritons in a transversely-applied magnetic field, is compared to previous research on single-interface plasmon polaritons. The reflectance from prism-coupled, nonlinear surface plasmons is analyzed using the infinite plane-wave approximation and a substrate nonlinearity which depends on the square of the transverse-electric field. Bistable switching requires incident intensities two orders of magnitude smaller for the long-range mode than for the single-interface mode. The regime in which the approximations are valid is shown to extend beyond that of first-order perturbation theory to guided waves that are very near cutoff. The sign and location of the nonlinearity become significant for these waves. For positive nonlinearities, nonlinear wave analysis indicates an additional branch of the reflected intensity curve, due to self-focussing of the guided wave. Positive and negative nonlinearities exhibit different switching intensities. The propagation constant of the long-range surface plasmon of a magnetic metal film is shifted by the application of a transverse magnetic field. The sign and magnitude of the shift are highly dependent on the metal thickness and the refractive indices of the bounding media. The shift is manifested experimentally as a resonant modulation of the reflectance from the prism-coupled surface plasmon due to changes in the angular position and width of the plasmon resonance. Experimental prism-coupling to the long-range surface magnetoplasmon in thin nickel films confirms the theoretical expectations for a wide variety of sample parameters. The phase of the magneto-optic coefficient is determined from the angular profile of the reflectance modulation. Although the shift of the propagation constant may be two orders of magnitude smaller for the long-range mode, the modulation signal is the same order of magnitude for long-range and single-interface magnetoplasmons.