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Laser and Fourier transform spectroscopy were used to study a variety of gas phase molecules. A series of calcium and strontium monoalkoxides, CaOR and SrOR [R=H, CH₃, CH₂CH₃, CH(CH₃)₂, CH₂CH₂CH₃, CH₂(CH₂)₂CH₃, CH₂(CH₃)CH₂CH₃ and C(CH₃)₃] was studied by laser induced fluorescence and laser excitation techniques. The A - X and B - X electronic transitions were recorded. Calcium and strontium monocyclopentadienide, CaCp and SrCp, were produced in a Broida oven and the spectra were recorded at low resolution by laser techniques. The geometry of these molecules is like an "open-faced sandwich", with C₅ᵥ symmetry. The A²Π - X²Σ⁺ and B²Σ⁺ - X²Σ⁺ transitions of calcium and strontium monoisocyanate, CaNCO and SrNCO, were recorded for the first time. The spectra are interpreted as arising from a molecule with linear, ionic Sr⁺ - ⁻NCO structure. The 0-0 band of the A - X transition of SrNCO was recorded at high resolution and rotationally analyzed. The use of a 0.64 m monochromator, acting as a narrow bandpass filter, was necessary for recording the spectra and enabled the correct assignment of the rotational lines. By comparing the molecular constants of SrNCO with related molecules, the NCO⁻ ligand was found to be nitrogen bonding to the strontium atom. The Sr-N bond length was estimated to be 2.26 A in the ground state. The rotational analysis of the 0-0 band of the A²E₁/₂ - X²A₁ transition of the SrOCH₃ free radical has been carried out by laser excitation spectroscopy. The SrOCH₃ molecule was found to have C₃ᵥ symmetry with a Sr-O bond length of 2.12 A. There was no evidence of a Jahn-Teller effect in the A²E state. This work is the first high-resolution analysis of a metal alkoxide molecule. The rotationally cool (30 K) spectrum of the 0-0 vibrational band of the A²Δ - X²Π electronic transition for the diatomic free radical CCl was recorded using a Fourier transform spectrometer. The first rotational lines of the six strongest branches were observed, and transitions in three other branches were also detected. The CCl radical was produced in a corona-excited supersonic expansion source.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / by David Hopkins Shoemaker. / M.S.

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Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by Monson H. Hayes. / Vita. Includes bibliographical references (leaves 134-139).

Thesis (M. Phil.)--University of Hong Kong, 1989.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

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The purpose of this research was to develop a more convenient method to distinguish bacteria using Fourier transform infrared (FT-IR) spectroscopy. The specular reflectance infrared spectra of bacterial colonies were obtained in-situ, without removing them from the agar growth media. The spectra of a variety of bacterial species were obtained by the infrared microscope and then were analyzed by factor analysis. Using this statistical method in conjunction with in-situ sampling we evaluated how well Grampositive species were sorted from Gram-negative species. Also, how the type of agar used and how the age of bacterial colonies affects the results of Gram stain predictions were evaluated; our experiments showed that the influence of those various conditions can be decreased. The suitability of various sets of standard spectra for predicting Gram stain, including sets constructed with and without Kramers-Kronig transformation and those constructed using partial regions verses the complete mid-infrared region, was evaluated.The effect that water on the surface of the colonies has been studied in distinguishing bacteria. Furthermore, the original method was improved and the method's suitability to differentiate a larger number of different bacterial species was examined. / Department of Chemistry