The UV-visible absorption spectrum of carbon vapor trapped in solid argon at low temperature contains many intense features, but only those of C₂ and C₃ have been identified. For this work, graphite vapor was produced under high vacuum conditions and condensed with argon onto a cold (∼10K) substrate. The resulting matrix-isolated carbon molecules were analyzed with both UV-visible and infrared absorption spectroscopy. Slight warming of the sample allowed formation of larger molecules and subsequent spectra traced the growth of their absorption features. The experiment associated infrared features to particular UV-visible features via their growth curves. The most reliable correlations are listed below. Theoretical calculations of equilibrium geometries and IR vibrational frequencies were performed on linear and nearly linear carbon chain molecules from C₃ to C₉ at the HF/SCF level of theory and from C₃ to C₇ at the MP2 level of theory, both using the 6-31G* basis set. Tentative assignment of the UV-visible features to molecules was made based on these considerations and on the following: the experimental IR/UV-visible correlations, previous experimental IR work, and modeling of the growth of the UV-visible features during matrix annealing. (UNFORMATTED TABLE FOLLOWS:) Molecule, UV-visible Feature (Å), IR Feature (cm⁻¹), Correlation Coefficient. C₃ (linear), 4100, 2040, .98. C₈ (linear), 3075, 1998, .97. C₈ (cyclic), 3900, 1804, .90. C₆ (linear), 2465, 1952, .86. C₇, 3480. C₉, 4480.

No description available.

With a large number of carbon-carbon spin-spin coupling constants now determined and the dihedral angle dependence of vicinal coupling constants reported, application of this coupling constants data was attempted to a conformational study.

No description available.

Ph. D.

An (e,2e) electron scattering spectrometer has been constructed and used for the first time to investigate the spectral momentum density of the valence bands of a solid target. This technique provides fundamental information about the electronic structure of both crystalline and amorphous solids. The three fundamental quantities, the band structure, electron density of states, and electron momentum distribution can be simultaneously derived from the measured (e,2e) cross section. A review of single electron and (e,2e) scattering theory is given with an emphasis on scattering from solids. The effects of multiple scattering are discussed and a method of deconvoluting those effects from the measured (e,2e) cross section is developed. There is a detailed description of the spectrometer design and operation with particular attention given to the electron optics and voltage distribution. The algorithms and software for computer aided data acquisition and analysis are also outlined, as is error analysis. The techniques employed in the preparation and characterization of extremely thin film samples of a-C and single crystal graphite are described. An analysis of the data taken for a-C samples is given. The data are compared with the results of complementary experiments and theory for graphite, diamond, and a-C which are given in a review of the literature. The existence of a definite dispersion relation ε(q) in amorphous carbon is demonstrated. The a-C band structure appears to be more similar to that of graphite than to that of diamond, however it differs significantly from both in some respects. The measured spectral momentum density seems compatible with a model of a-C based on small, randomly-oriented islands of quasi-2D graphite-like continuous random network structures. However, no definitive interpretations can be made until higher resolution experiments are performed on both a-C and single crystal graphite. / Ph. D.