The use of picosecond time-resolved spectroscopic techniques to probe reaction dynamics provides valuable information about the initial steps of photochemical reactions. For accurate interpretation of data collected by means of these methods, it is imperative that the inherent limitations of the picosecond absorption and emission spectrometers are considered. Results obtained via picosecond spectroscopic methods are presented which increase our understanding of the photochemistry and photophysics of three classes of molecular systems. / From our investigations of a series of halosubstituted fluorenes in cyclohexane, it is shown that bond homolysis and intersystem crossing to the triplet manifold occur on a rapid ($<$20-40 ps) and competitive time scale in 9-halofluorenes. It is demonstrated through a discussion of possible dissociation modes which are consistent with the experimental data that photodissociation is best described as occurring exclusively from the excited singlet state, and that no dissociation pathways originating from the lowest excited triplet state are operative. / The results of transient absorption measurements on a series of substituted diphenylhexatrienes support assignments of the observed bands which are contradictory to previous reports. A critical discussion of the earlier interpretations based on instrumental artifacts and limitations is provided. The results of the effect of changing solvent polarizability, solvent polarity, substituents, and temperature are described and support the present assignments. The observed trends in the decay kinetics of the absorption bands with changing solvent and substituents are consistent with theoretical expectations. / The synthesis and spectroscopic characterization of a series of proton-transfer fluorophores derived from 3-hydroxyflavone are described. This investigation has led to the conclusion that these types of structural changes permit the tuning of the spectroscopic behavior of these dyes only within a narrow window, and that the classical tradeoffs expected between quantum efficiency, fluorescence lifetime, and extinction coefficient are observed. Assessment of the usefulness of the twenty-two compounds studied as secondary fluors in scintillating plastics leads to the identification four promising candidates. Positive factors in the assessment are a high extinction coefficient, high quantum yield for proton-transfer emission, and short proton-transfer fluorescence lifetime as compared to 3-hydroxyflavone. / Source: Dissertation Abstracts International, Volume: 56-11, Section: B, page: 6081. / Major Professor: Edwin F. Hilinski. / Thesis (Ph.D.)--The Florida State University, 1995.

Solid state $\sp{13}$C NMR, Inverse Gas Chromatography and elemental analysis have been used to study the early diagenesis of organic matter of peat deposits from the Florida Everglades and to develop correlations between the structure of the organic matter and its affinity for non-polar organic compounds. / The structure of the sedimentary organic matter and its fraction was studied by solid state $\sp{13}$C NMR cross polarization and dipolar dephasing NMR experiments. The changes in the different polar, aliphatic and aromatic groups are used to discern the different chemical pathways that operate during early diagenesis. In addition, the degree of substitution of the aromatic structures of the sediments, and the effect of acid dissolution of minerals on the structure of sedimentary organic matter were studied. NMR methodology to provide reliable information about the functional group distributions of sedimentary organic matter as well as the various factors that affect the reliability of the NMR measurements are also discussed. / $\sp{13}$C NMR and elemental analysis of the sediments indicate that the carbohydrate is selectively degraded while aromatic structures were preserved. The structure of the organic matter becomes more reduced and crosslinked with age. / IGC was used to evaluate relative affinity of these peats and their fractions for a number of selected non-ionic organic compounds. The different fractions of the organic matter were used as stationary phases and non-ionic organic compounds are used as chromatographic probes. Their elution patterns and retention volumes were used to calculate activity coefficients. The relative affinity of the sedimentary organic matter and its fractions as a function of their chemical composition and origin was then investigated as well as the role of the different fractions of the organic matter in the total sorption process. Experimental results indicate that the lipid fraction plays a dominant role in the sorption process and that the affinity of intact sediments, humin and humic acid fractions is dominated by their relative distribution of polar, aliphatic and aromatic groups. Sorption-structure response surfaces were used to express the relationships between polarity and affinity in these organic sediments. / Source: Dissertation Abstracts International, Volume: 51-01, Section: B, page: 0110. / Major Professor: William Theophilus Cooper, III. / Thesis (Ph.D.)--The Florida State University, 1989.

The chemical reactivity of C$\sb{60}$ makes it an ideal candidate for the addition of derivatives and sidechains. Early derivatives involved the addition of metals such as osmium, ruthenium, and platinum. C$\sb{60}$ was soon found to hydrogenate via Birch reduction, halogenate, react with free radicals, and undergo cycloaddition with diazomethanes. This last addition process is of particular importance, because all other reactions add to the cage by breaking double bonds, thereby disturbing the total conjugation of the system. The bridging mechanism of the cycloaddition system preserves this conjugation which may be valuable for studies involving electron transfer. / Thiols, disulfides, and dialkyl sulfides have all been demonstrated to chemsorb to clean surfaces of gold, silver, copper, and platinum. Functionalized molecules containing these groups, may be studied at surfaces as true monolayers, as an alternative to films formed by the Langmuir-Blodgett technique. / The diazo cycloaddition of a sulfur derivative to C$\sb{60}$ may provide the first true monolayer of an undisturbed fullerene, and a more thorough insight into the electronic behavior of this interesting molecule. / This work discusses the purification processes of the fullerene and the synthetic route to the preparation of these derivatives. / Source: Dissertation Abstracts International, Volume: 56-08, Section: B, page: 4288. / Major Professor: Joseph B. Schlenoff. / Thesis (Ph.D.)--The Florida State University, 1995.

<p> Human biomonitoring is an analytical challenge to find environmental organic chemicals of varying polarity, persistency, and potential toxicity in a suitable, ideally non-invasive matrix at ppb levels that are significantly above method blanks. Compared with more traditional matrices of adipose tissue, serum, and urine, toenail clippings samples are non-invasive, compact, can be shipped without refrigeration, stored indefinitely at room temperature, and processed without concerns for biohazards. With both hydrophilic and hydrophobic layers, toenails contain 1-2% lipid, which is several times higher than serum. Toenails grow slowly and are trimmed every 2-3 months, which offers the potential to integrate both chronic and pulsed episodic exposures. Using toenail samples (65 to 340 mg) donated from four individuals and an indoor house cat, the hypothesis that toenails are a suitable biomonitoring matrix was tested by analyzing for persistent pesticides, over 50 PCB congeners, moderately persistent PBDEs, and transient compounds of triclosan and bisphenol A by using GC/High Resolution MS (GC/HRMS) analysis and for unsuspected compounds using GC/full scan MS. Although not fully digested and dissolved, toenails averaged 1.22% lipid (sd 0.20%, n=10). Lipid was separated and determined using a new small single-use 2-g S-X3 gel permeation chromatography flash column with high purity nitrogen. Multiple toenail samples from one individual were collected for over a year for replicate analysis, p,p&rsquo;- DDE averaged 0.82 ng/g-nail, sd 0.28, n=5 and 65.2 ng/g-lipid, sd 15.3, n=5 on lipid-adjusted basis. <i>Trans</i>-nonachlor averaged 3.08 ng/g-nail, sd 1.03, n=5; mean 254 ng/g-lipid, sd 97, n=5. PBDE 28 averaged 0.29 ng/g-nail, sd 0.10, n=5; mean 24.8 ng/g-lipid, sd 13.3, n=5. PBDE 85 averaged 0.25 ng/g-nail, sd 0.06, n=5; mean 20.8 ng/g-lipid, sd 6.2, n=5. PBDE 153 averaged 1.82 ng/g-nail, sd 0.51, n=6; mean 150 ng/g-lipid, sd 49.3, n=6. Most effectively biomonitored in toenails were normally transient triclosan (mean 58.3 ng/g-nail, sd 6.6, n=2), chlordanes, DDT, PBDEs, and PCBs including congeners with 2,5- or 2,3,6-chlorine substitution (PCBs 52, 49, 44, 70, 95, 101, 87, and 110), which are suspect neurotoxins, but are rarely found in extant serum biomonitoring data. Toenail soap wash samples indicated little (&lt; 4%) or no exogenous contamination, except for the musks galaxolide and tonalide in most samples, which ranged up to 30%, likely from topical application. The one cat toenail sample had elevated concentrations of PBDEs and especially chlordanes. Unsuspected tentatively identified compounds included a UV Filter compound, octocrylene, a hydroxyl-methyl benzothiazole, and several compounds used in flavors or fragrances.</p><p>

<p> Mass spectrometry (MS) is an efficient analytical tool due to a number of advantages for providing high sensitivity, high-throughput analysis and less sample consumption. Since 1897, MS has continued to evolve and significant developments have occurred in the area of ionization techniques. Since 2010, inlet ionization techniques have shown the potential to compete in the areas of sensitivity and sample conservation with electrospray ionization (ESI) and matrix assisted laser desorption/ionization (MALDI). Matrix assisted inlet ionization (MAI) produces multiply charged ions within a mass spectrometer inlet without the need of high voltage, a laser or nebulizing gas. For MAI, sample preparation can be critical affecting the sensitivity, reproducibility and carry over. This dissertation presents new sample preparation techniques which have shown substantial improvement in sensitivity and reproducibility. The limit of detection can be achieved to less than 50 amol with the new sample preparation technique. Furthermore, this new sample introduction process enhance matrix assisted ionization (MAI) and solvent assisted ionization (SAI)&rsquo;s ability to couple with Thin-layer chromatography.</p><p>

Source: Dissertation Abstracts International, Volume: 38-09, Section: B, page: 4189. / Thesis (Ph.D.)--The Florida State University, 1977.

In emission spectral measurement with a dispersive spectrometer, if the entrance slit is widely opened, more light from a relatively large sample area can be collected, thus both energy throughput and spatial averaging advantages can be achieved in the measurement. With the entrance slit widely opened, the spectral bandpass becomes large. Radiations of different wavelengths likely fall on the same area of the detector. This can lead to a multiplex advantage and also extend the accessible wavelength range for a given spectral window. / The problem for opening the entrance slit is the decrease of spectral resolution. This project aimed to overcome this problem so that all the advantages associated with opening entrance slit are retained without loss of spectral resolution. The research we have done to solve this problem is to apply Hadamard transform and deconvolution in spectral measurements. The way we implement Hadamard transform in emission spectroscopy is to take spectra with a Hadamard mask in place of the conventional entrance slit, then inversely transform the measured data to recover the well-resolved spectra with improved signal-to-noise ratio. A spectrum can also be taken simply with the entrance slit widely opened. By deconvolving the slit function with such a wide-slit spectrum a best resolved spectrum can be recovered. Major difficulties involving in deconvolution have been discussed in Chapter 5 of this dissertation, and a novel algorithm is proposed there as well. Another important aspect involved in this project is the incorporation of fiber optics with Hadamard transform and deconvolution in spectral measurements. This greatly improved the flexibility and collection efficiency in our measurement system. / Source: Dissertation Abstracts International, Volume: 52-10, Section: B, page: 5236. / Major Professor: Charles K. Mann. / Thesis (Ph.D.)--The Florida State University, 1991.

No description available.

No description available.

No description available.