Since its inception, nuclear magnetic resonance has proved to be a fruitful area of research, and one of the most recent advances is in its application to the imaging of structure within objects. The original technique used, known as projection-reconstruction, is rather sensitive to errors in the magnetic fields and on its own is not practicable for full 3-d imaging, so interest has turned to a number of alternative methods. The technique investigated here, selective excitation, achieves imaging by the use of excitation sequences which can restrict the signal response to chosen regions of a spin sample. In order to make use of the Fellgett advantage, the ideal situation in this case would seem to be to confine excitation to a column of spins from which various properties can then be 'read out' by application of a lengthwise gradient.

The main objective of this work was the development of the existing shock tube system so that it could be used for kinetic investigations. As a result of the many modifications and alterations to the shock tube, and thorough and successful characterisation experiments, the shock tube is now considered to be suitable for the study of high temperature gas phase reactions. One of the important features of the characterisation experiments was the dependency of several shock parameters (P2(expt), P5(expt), and Mr) on the initial test gas pressure in the shock tube. Shock parameters have been determined which take into account non-ideal behaviour such as side wall boundary layer formation. The atomic resonance absorption spectroscopy (ARAS) detection technique was only installed during the latter stages of this work, and due to time restrictions is not yet fully operational. When this is achieved the shock tube at Aberdeen will be the only shock tube in the U.K. where time resolved, gas phase reactions, can be kinetically investigated. Results from Brookhaven National Laboratory, New York, are presented where a similar shock tube - ARAS system was calibrated for atomic oxygen. Nitrous oxide (N2O) was used as a clean source of O atoms, and the bimolecular rate expression for the reaction: N2O + M N2 + O + M. over the temperature range 1266 T(K) 2311 was determined to be: k (cm3molecule-1s-1) = (1.220.19)x10-9 exp (-57861600 cal/RT). This rate expression is in good agreement with literature values.

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Calculations have been performed to obtain accurate cross-sections and thermally averaged rate coefficients for the rotational excitation of methanol by helium, using the Coupled States quantum-mechanical approach. Transitions within the ground and first torsionally excited states of A and E- type methanol were considered. The 'propensity rules' governing the collisional transitions were examined and compared with the results of microwave double resonance experiments. Predictions are made of line intensity ratios which are sensitive to the density of the He perturber and which lend themselves to the determination of the perturber densities in astrophysically interesting regions of molecular clouds.

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Raman Spectroscopy for the identification and classification of malignancy in the oesophagus has been demonstrated in this thesis. The potential of Raman spectroscopy in this field is twofold; as a adjunct for the pathologist and as a biopsy targeting tool at endoscopy. This study has demonstrated the feasibility of these potential applications in vitro. Spectral diagnostic models have been developed by correlating spectral information with histopathology. This is the current 'gold standard' diagnostic method for the identification of dysplasia, the established risk factor for the development of oesophageal cancer. Histopathology is a subjective assessment and widely acknowledged to have limitations. A more rigorous gold standard was therefore developed, as part of this study, using the consensus opinion of three independent expert pathologists to train the diagnostic models. Raman spectra have been measured from oesophageal tissue covering the full spectrum of malignant disease in the oesophagus, using a near infrared Raman spectrometer customised for tissue spectral measurements. Two spectral datasets were measured with different volumes of tissue probed using twenty and eighty times magnification ultra long working distance objectives. Multivariate statistical analysis has been used to extract the required spectral information with the greatest discriminative power. Principal component fed linear discriminant spectral models have been tested with leave one out cross validation procedures. Three pathology group models have correctly classified up to 91% of spectra, and eight group models have correctly classified up to 82% of spectra. Optimisation of the spectral models by selection of significant principal components, filtering the data and using staggered models was investigated. Effort has been made to understand the findings in their clinical context, with review of patient history and clinical progress, long term follow up is required. Preliminary work projecting independent data on to the models has been encouraging with 76% of the spectra in the three group model correctly classified, approaching classification levels of the training dataset. Formalin fixed tissue models were demonstrated to perform well, with 80% of the spectra were correctly classified in the seven group model. This further demonstrates the potential of Raman spectroscopy as a pathology tool. If Raman spectroscopy is to be implemented in a clinical setting it must be transferable between different measurement systems. This has been evaluated with oesophageal tissue spectra measured on two systems using three objectives. Simple calibration has demonstrated the use of multiple systems and measurement parameters in the development and application of spectral classification models. Testing of a new design of fibre probe has provided encouraging preliminary results. There is potential for the application of Raman spectroscopy in vivo, however the technology remains immature. Spectral maps of samples taken from across the spectrum of disease have shown clear delineation of the morphological features seen on the H&E images. Furthermore the biochemical information elicited has been analysed. Initial measurements of oesophageal tissue using multiphoton imaging have demonstrated the potential of collagen autofuorescence in the diagnosis of malignant change.