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No description available.

The application of Fourier transform infrared spectroscopy (FTIR) to the characterization of materials in art and archaeology is evaluated. The diffuse reflectance accessory was used extensively and an infrared microscope was utilized for microscopic samples. The development and theory of diffuse reflectance FT-IR spectroscopy are given and a brief outline of previous use of infrared spectroscopy in archaeological and art conservation is included. The experimental procedures and sample handling used in the research are explained in detail. Diffuse reflectance spectra of several classes of organic materials available in antiquity are presented. The classes of organic materials include waxes, fats and oils, bituminous materials, resins, amber, shellac, pitch, gums and gum resins and proteins. The spectra of the reference materials are interpreted in the light of the known information on chemical structure. Several examples of archaeological specimens which have been characterized are included. Two large groups of modern materials, a group of plastic sculptures and a collection of early plastic objects were characterized. Areas for future work include an expanded reference collection of modern materials and the use of J-CAMP-DX programming language for interlaboratory exchange of data which is independent of the brand of spectrometer used.

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The main part of this thesis concerns the design and simulation of a polarization analysis backscattering cold neutron spectrometer, OSIRIS, at the ISIS pulsed neutron source. The OSIRIS instrument consists of two parts, a high-resolution powder diffractometer and a micro-eV resolution inelastic spectrometer. The incident cold neutron beam has the option of being polarised by means of a series of interchangeable polarising benders. The inelastic spectrometer consists of an analyser array constructed from pyrolytic graphite crystals situated in nearbackscattering geometry. Monte Carlo simulations have been performed in order to optimise and investigate various components of the spectrometer, including the guide, polarisers and analyser. A microguide testing device, MITED, has been constructed, commissioned and, using it, measurements have been made on neutron guide sections. This instrument has also been used to test the reflectivity of supermirror coated guide sections. Originally, it was the aim of this thesis to carry out all the scientific commissioning experiments required for OSIRIS. This has become unfeasible due to manpower problems within the ISIS facility, which have delayed the construction of the OSIRIS spectrometer and have moved it out of the time range of this thesis. Therefore an extra section of work has been included, on a family of intermetallic metal hydride systems that it will be of interest to investigate using the OSIRIS instrument. A general study of the diffusion of hydrogen in C15 Laves phase intermetallic compounds has been performed. This has employed the techniques of quasielastic neutron scattering, inelastic vibrational spectroscopy, diffraction and muon spectroscopy.

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This thesis describes the characterisation of a range of sol-gel silicas, mainly by the physical techniques of NMR cryoporometry, density and imbibation measurements and Small Angle Neutron Scattering. The developments made to these techniques as part of this work include Construction of the frst full cool/warm cycle automated NMR cryoporometer, with continual pore size distribution graphing. Calibration of melting point constants with respect to gas-adsorption and neutron scattering. Detailed characterisation of the thermal properties of the cryoporometer. Development and measurement of the rst multi-dimensionally resolved pore size maps by NMR cryoporometry. Demonstration that simple density and imbibation measurements can, when combined with models, provide a wealth of information concerning the silicas. Development of novel continuous medium Monte-Carlo integration methods to calculate the solid-solid density correlation function for porous media, showing excellent agreement with experimental SANS results. In particular, with the second point, there has been an attempt to use SANS to provide an absolute calibration scale for pore size, nominally given by gas-adsorption.

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Raman spectroscopy is potentially a useful technique for the analysis of thioethers and thiols because of the characteristic set of bands which appears in the C-S stretching region. A review of previous studies on Raman band intensity measurements is presented in which the experimental difficulties and influencing factors are given. An experimental system has been developed around a Coderg PHO Raman spectrometer for the measurement of absolute Raman band intensities. This includes the novel use of a Pockels cell for the accurate determination of depolarisation ratios. Carbon tetrachloride has been assessed as a suitable internal standard for use with this system. Raman band intensities are given for five thioethers and two thiols. Several bands are identified as being characteristic of sulphur-containing hydrocarbons. Analysis of bands in the C-S stretching region is accomplished by considering the intensity contributions provided by individual groups in the molecule, resulting in a successful prediction of the C-S stretching band intensities for t-butane thiol. In addition, temperature studies have been conducted for ethyl methyl sulphide in order to attempt calculation of the energy barrier between the two conformations. A computer programme has been developed for the theoretical calculation of Raman band frequencies and intensities. Molecular parameters have been derived for dimethyl sulphide, including an ab initio force field. Tests for transferabilityof these data to ethyl methyl sulphide and deuterated dimethyl sulphide have produced encouraging results. A study of infra-red intensities of thioethers has been carried out. This is an extension of some previous work in which the necessity to resolve individual bands is eliminated. For several discrete spectral regions quantification is made of the effects of a sulphur atom on C-H band intensities, thus allowing successful intensity predictions for other molecules studied. Suggestions for further work in this field are given.

The use of immobilized enzymes (and cells) in flow analyses and some determinants of the performance of the resulting analytical systems have been examined; the detector used in most cases was the LKB 2017-30 flow microcalorimeter. The detector time constant and sensitivity, reactor enzyme activity, flow rate and the mode of sample injection were primary determinants of system characteristics such as, sensitivity, minimum detectable concentration, linearity range and speed analysis. These relationships were later applied in the determination of the reaction enthalpy. Glucose, urea, fructose, mannose, glucoseamine, the cofactor ATP, vitamin C and hydrogen peroxide were also determined using the appropriate immobilized enzymes. The kinetics of the reactions catalysed by immobilized urease, glucose oxidase, acetylcholinesterase or ascorbate oxidase was studied via flow microcalorimetry. Apparent intrinsic kinetic parameters, external and internal substrate moduli, as well as the corresponding effectiveness factors were determined. In all cases,the Michaelis constant (Km) was increased and the observed activity severely limited as a consequence of the slow diffusion of substrate. Flow analysis using immobilized cells and microcalorimetric monitoring was also examined. This combination is well suited for broad-spectrum analysis. The effects of selected organic solvents (permeablizing agents) on the linearity range (approximately given by the Km) was also of some interest. The specificity (estimated as (dQ/dt)max/KmaPP) for a range of substrate was proposed as a means of differentiating between closely related strains of cells. Electrochemical monitoring of immobilized enzyme reactions may rival the thermochemical approach in its widespread applicability and simplicity. Both potentiometric and amperometric modes were used; the latter in connection with flow analyses. Two amperometric enzyme reactors and a flow-through enzyme electrode were constructed and successfully used in substrate determinations.