Researchers analyzing the upper clouds of Jupiter and Saturn are unable to theoretically reproduce the data returned by Pioneers 10 and 11 and Voyagers 1 and 2 with an approach based on Mie theory. Ammonia crystals are believed to be an important constituent of Jupiter's upper clouds, but both their shape and scattering properties were unknown at the start of this work. Ammonia crystals and water crystals were grown in a cold chamber at temperatures 20°C below their freezing points (0°C and -77.7°C, respectively). The H₂O crystals formed had shapes in agreement with published growth habit diagrams. The NH₃ crystals formed were usually irregular in shape, but regular four-sided pyramids were commonly observed. This four-sided pyramidal shape is in agreement with ammonia's primitive cubic crystal structure. Ammonia crystals could not be formed at temperatures above -95°C due to nucleation problems. A scattering measuring instrument was constructed with fifteen separate lens-detector combinations aimed at a common point in the center of the cold chamber. A laser beam (6328Å wavelength) traversed the chamber center, illuminating any crystal aerosal clouds present. A computer was used to rapidly sample the outputs of the fifteen detectors and to drive a photoelectric modulator to change the slow speed polarization properties of the laser beam. The measurements resulted in a determination of the single scattering phase function and degree of linear polarization for the crystal species present. Water crystals were found to have scattering properties similar to that reported by previous researchers. The H₂O crystal scattering possesses a smaller backscatter peak and smaller polarization features than is common for water spheres of similar size. A negative polarization of 5% occurred in the forward scattering hemisphere and a positive polarization of 10% in the rear. Ammonia particles were observed to have a backscattering peak four times higher than for water crystals. The NH₃ particle light scattering produced very little polarization of the scattered light. A small (∼ 4%) negative polarization occurred in the forward scattering hemisphere. Work is continuing here to make scattering measurements using blue light illumination nearly simultaneous with the red HeNe laser wavelength illumination.

In this dissertation, I examine the optical linear polarization of quasi-stellar objects (QSOs) and BL Lacertae objects. I present extensive polarimetric observations of a large sample of QSOs, systematically analyze the correlations between polarization and other properties of QSOs, compare t

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Raman spectroscopy is a powerful tool in oncological imaging. Optical biopsies in which an accurate diagnosis of the tumour areas is spectroscopically performed are especially interesting for application to skin cancer treatments. In the first part of this dissertation a study on automated Raman spectral imaging allowed accurate diagnosis and delineation of the borders of a common type of skin cancer, basal cell carcinoma (BCC). Automated detection and imaging of BCC in skin sections excised during surgery was performed by combining Raman micro-spectroscopy with supervised multivariate mathematical algorithms based on linear discriminant analysis (LDA). The model allowed 90±9% sensitivity and 85±9% specificity in BCC detection. Raman spectral images based on the LDA model were created and compared with the gold-standard of the conventional histopathological diagnoses resulting in excellent agreement. Additional studies on the ability of the model in discriminating between BCC and hair follicles produced accurate diagnoses. In this thesis instrumental implementation and design of a Raman spectral imaging prototype aiming to reduce the acquisition time required to build the Raman spectral images was developed. High sensitivity variants of Raman spectroscopy such as surface enhanced Raman spectroscopy (SERS) are known to enable optical detection down to single molecules and can be applied to thin supported lipid research. The combination of SERS with a complementary topographic technique simultaneously synchronised adds to the chemical information the morphology of the sample surface. In the second part of this thesis simultaneous atomic force microscopy (AFM) and SERS characterisation of thin (≈15-20 nm) supported films of arachidic acid and cationic phospholipids on sapphire/silver substrates was successfully achieved. Supports were fabricated with nanosphere lithographic procedures and allowed enhancement of the weak Raman signals from the amphiphilic films by a maximum factor of ×10^8.

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