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The ability to measure and understand protein fluorescence depends on the development of light sources which can excite the intrinsic aromatic amino acids, tryptophan, tyrosine, and phenylalanine. In recent years the time-resolved study of protein fluorescence has been limited to the excitation of tryptophan and tyrosine. The availability of the shorter wavelength, 265nm light source, allows for the excitation of phenylalanine which until recently has been limited. In this thesis the direct excitation of phenylalanine is demonstrated, using pulsed light emitting diodes, and the bi-exponential nature of its fluorescence decay is investigated, and the effect of pH on the fluorescence lifetimes. One of the major difficulties with the study of proteins is the lack of immobilisation techniques for the study of proteins at the single-molecule level, which provide little perturbation of the protein. To try to achieve this, the fabrication of novel molecular nanoenvironments, based on sol-gel techniques, which allow control and enhancement of protein fluorescence has been developed. In this thesis the application of sol-gel techniques is demonstrated for the environment sensitive trimeric form of allophycocyanin (APC) at both the ensemble and single-molecule level. The optimisation of the sol-gel technique as a generic approach to entrapment of proteins was developed using the environment sensitive probe 6-propionyl-2-(N,N-dimethylamino)naphthalene (PRODAN), which enabled monitoring of the hydrolysis and methanol removal stage of the process. For earlier diagnosis, ultra sensitive monitoring and breakthroughs in understanding the causes of many diseases, we urgently need to develop clinical single molecule sensing. Downstream, this might be accomplished by means of the fluorescence nanosecond/nanometre microscopy of single biomacromolecules.

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This thesis is primarily concerned with the design and construction of apparatus to investigate the behaviour of non-metallic magnetic materials in their transition from a disordered to an ordered state as the temperature is reduced. The work has been directed towards making equipment - (a) to perform both Spin Echo and Fast Fourier Transform Nuclear Magnetic Resonance (FFT NMR) and (b) to establish and control the temperature of any particular sample within fine limits through the liquid helium range. The operation of the NMR spectrometer has been verified by tests using copper sulphate solution, and proton FFT NMR line-width experiments have been performed with the aim of discovering the behaviour of cobalt formate Co (H000)2.2H20, in its transition to antiferromagnetic order at 5.12 K. In fact, another material, manganese phyrophosphate, was the initial choice for investigation because of its interesting magnetic structure; however, after numerous unsuccessful attempts to grow a single crystal on the part of the author and the Radar Research Establishment, Malvern, the alternative of cobalt formate was taken up. Proton NMR line-width work on cobalt formate near its critical point is considered most useful for the purpose of classifying the material more fully and testing the predictions of recent critical phenomena theory. The results obtained in these investigations indicate a dramatic broadening of NMR lines at 5.12 K. This estimate of its Neel temperature is in agreement with the results of other researchers using non-NMR line-width methods. The theoretical background of NMR line broadening at the critical point is reviewed and the temperature dependence of NMR line-widths is derived for a model approximating the behaviour of cobalt, formate, viz, the two dimensional Ising antiferromagnet. Comparison is also made between the reported proton NMR line-width temperature variation of manganese formate and recent theory on the two dimensional Heisenberg antiferromagnet.

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