Graduation date: 2000

Thesis (Ph. D.)--University of Florida, 1981. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 76-79).

Thesis (Ph. D.)--University of Wisconsin, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

Typescript (Photocopy) Bibliography: leaves vii-xiv. (second sequence)

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Not available / text

Les temps de declin de la luminescence de KCl:Ga('+), KBr:In('+), KI:Sn('2+), KI:Tl('+) ont ete mesures dans la region de temperature 3.3-300K; l'analyse des resultats permet d'obtenir des renseignements detailles sur la surface d'energie potentielle adiabatique de l'etat excite relaxe. / Une etude des temps de declin sous champ magnetique est presentee; les resultats sont interpretes a l'aide de la theorie des perturbations en premier ordre a l'interieur d'un modele ou le couplage electron-reseau (effet Jahn-Teller) domine le couplage spin-orbite. A basse temperature, la probabilite de transition radiative varie lineairement avec le carre du champ magnetique; la presence de composantes independantes du champ dans le signal de declin de luminescence permet la determination de la symetrie de l'etat excite relaxe. La valeur du parametre g (facteur de Lande) de l'etat excite est obtenue de l'analyse des donnees. / On a pu ainsi attribuer une nouvelle bande d'emission de KI:Sn('2+) a un dimere d'ions Sn('2+) accompagne de lacunes cationiques stabilisatrices. De meme, l'origine de la bande A(,x) de KI:Tl('+) a ete attribuee a un minimum de symetrie trigonale sur la surface d'energie potentielle adiabatique de l'etat excite relaxe.

Thesis (Ph. D.)--University of Adelaide, 1989. / Typescript (Photocopy). Includes bibliographical references (leaves vii-xiv. (second sequence)).

Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, August 1998. / Includes bibliographical references. Also available on the Internet.

Three classes of new photoreactions were discovered and their reaction mechanisms investigated. These reactions are related in that the same critical o-quinonemethide intermediate is involved in the mechanism of each reaction. The first reaction is the photocyclization of 2-(2’-hydroxyphenyl)benzyl alcohol (1) and derivatives to 6H-dibenzo[b,d]pyrans (e.g., 7 from 1), with excellent chemical (>95%) and quantum yields (Φp = 0.50 for 7 from 1 in basic solution). Results from investigations of structure-reactivity, pH-effects and fluorescence data suggest that, in neutral solution, the primary photochemical step involves ionization of the phenol moiety to phenolate ion in S1, which is probably concerted with twisting of the phenyl rings, to give a more planar species in S,. The subsequent dehydroxylation step of the benzyl alcohol moiety, to give o-quinonemethide 20, is initiated by a charge transfer from phenolate to the adjacent phenyl ring. The thermal ring closure of 20 competes with nucleophilic solvent (e.g., H20 or MeOH) capture, to give observed pyran 7 and alcohol 1 (by H20) and 5 (by MeOH), respectively. In moderately strong acidic media, acid-catalyzed photosolvolysis occurs, to give carbocation 21 which can also cyclize to afford pyran 7. The second photoreaction is the photocyclization reaction of 2- phenoxybenzyl alcohols 22 and 23 to give dibenzo[b,d]pyrans 7 and 29, respectively, in aqueous solution. The primary photochemical step is believed to involve initial aryl-O bond homolysis followed by rearrangement to give alcohol 1, which cyclizes to observed pyran 7 upon secondary photolysis. The meta-substituted isomer 24 did not produce cyclized photoproducts, but instead gave isomeric hydroxybiphenyls which are also derived from initial aryl-O bond homolysis followed by simple radical recombination. The photocyclization appears to be general for the ortho-phenoxybenzyl alcohol system, in which an appropriate assembly of phenoxy and hydroxymethyl (CH2OH) functional groups is a necessary requirement. In acidic solution, a competing proton-assisted photosolvolysis reaction, via heterolysis of the benzylic C-OH bond, takes place for all these compounds, to give carbocation intermediates which were subsequently trapped by the solvent. The last reaction is the photoisomerization of xanthene (26) to pyran 7 (~70% yield and Φp ~ 0.0035 in aqueous solution). In addition to 7, 2- benzylphenol (40) (Φ = 0.001), 9,9’-bixanthyl (41) (Φ < 0.001) and alcohol 1 (Φ < 0.001) were also observed as minor products in the reaction. The photoisomerization is again initiated by aryl-O bond homolysis in S1, to give a singlet phenyl/phenoxy biradical 48 which undergoes a radical ipso-attack on the adjacent phenyl ring, followed by rearrangement to afford o-quinonemethide 20, which cyclizes to form pyran 7 in competition with nucleophilic solvent capture to give 5 (by MeOH). Xanthene derivative 42 also photoisomerizes to the corresponding pyran derivative 29, which was obtained in much lower yield due to secondary photochemistry of 29. / Graduate