This research is focused on the synthesis and characterization (BET, transmission electron microscopy and optical spectroscopy) of aluminum oxide condensates via a static sintering process and dynamic process of pulse laser ablation (PLA) and pulse laser ablation in liquid (PLAL). For a start, the static route of an onset coarsening-coalescence event based on the incubation time of cylindrical mesopore formation and a significant decrease of specific surface area by 50% and 70% relative to the dry pressed samples was determined by N2 adsorption-desorption hysteresis isotherm for two Al2O3 powders having 50 and 10 nm in diameter respectively on an average and with £^-type related structures, i.e. £^- and its distortion derivatives £_- and/or £c-types with {100}/{111} facets and twinning according to transmission electron microscopy. In the temperature range of 1100 to 1400oC, both powders underwent onset coarsening-coalescence before reconstructive transformation to form the stable £\-type. The apparent activation energy for such a rapid coarsening-coalescence event was estimated as 241 ¡Ó 18 and 119 ¡Ó 19 kJ/mol, for 50 and 10 nm-sized particles, respectively indicating easier surface diffusion and particle movement for the latter. The size dependence of surface relaxation and onset coarsening-coalescence of the £^−type related Al2O3 nanoparticles agrees with their recrystallization-repacking upon electron irradiation and accounts for their assembly into nano chain aggregates or a close packed manner under the radiant heating effect in a dynamic laser ablation process. In addition, ultrafine (5 nm) Al2O3 nanoparticles having a predominant £\-type structure and with an internal compressive stress up to ca. 15 GPa were synthesized by pulsed laser ablation on Al target under a very high peak power density (1.8x1011 W/cm2) with oxygen flow in vacuum. The ultrafine £\-Al2O3 was alternatively formed from the minor £^-Al2O3 nanocondensates upon electron irradiation. In such a case, the polymorphs follow a special crystallographic relationship [110]£^//[2110]£\; (111) £^//(0114)£\ with a mixed mismatch strain yet nonparallel close packed planes indicating a reconstructive type transformation. The formation of metastable £\-Al2O3 in the dynamic processes can be rationalized by the kinetic phase change from the amorphous lamellar and/or £^-Al2O3 depending on their free energy versus cell volume curves. The dense and ultrafine sized Al2O3 polymorphs with a rather low minimum band gap of 3.7 eV shed light on their natural occurrence in dynamic settings and abrasive as well as catalytic/optoelectronic applications. Furthmore, pulsed laser ablation in water under a high peak power density of 1.8 ¡Ñ 1011 W/cm2 using Q-switch mode and 1064 nm excitation was used to fabricate (H+,Al2+)-codoped Al2O3 nanocondensates having £^- and its derivative £c-type structure as characterized by electron microscopy and spectroscopy. The as-formed £^- and £c-Al2O3 nanocondensates are mainly 10 to 100 nm in size and have a significant internal compressive stress (> 10 GPa) according to cell parameters and vibrational spectroscopy, due to a significant shock loading effect in water. The £^-Al2O3 nanocondensates are nearly spherical in shape but became cubo-octahedra when grew up to ca. 100 nm to exhibit more facets as a result of martensitic £^¡÷£c transformation following the crystallographic relationship (3 11 )£c //(02 2)£^; (0 2 4 )£c//(3 11)£^. The formation of dense and (H+,Al2+)-codoped £^/£c-Al2O3 rather than aluminum hydrates sheds light on the favored phases of the Al2O3-H2O binary at high temperature and pressure conditions in natural dynamic settings. The nanocondensates thus formed have a much lower minimum band gap (5.2 eV) than bulk £\-Al2O3 for potential optocatalytic applications. Moreover, the Al2O3 nanocondensates of spinel-type related structures, i.e. £^- and £c- type with a significant internal compressive stress via pulsed laser ablation in water were subjected to prolonged dwelling in water to form columnar bayerite plates for further transformation as platy £^-Al2O3. Transmission electron microscopic observations indicated the £^-Al2O3 follows the crystallographic relationship (100)b//(011)£^; [001]b//[111]£^ with relic bayerite (denoted as b). The £^-Al2O3 also shows {111} twin/faults and rock salt-type domains due to dehydroxylation of bayerite which involves {111} shuffling and disordering of the Al ions in the octahedral and tetrahedral sites. The combined evidences of X-ray photoelectron spectroscopy, vibrational spectroscopy and UV-visible absorbance indicated that the H+, Al+ and Al2+ co-doped bayerite and £^-Al2O3 composite plates have a minimum band gap as low as ~ 5 eV for potential catalytic and electro-optical applications in water environment. Finally, pulsed laser ablation in aqueous solution of NaOH up to 1 M was employed to fabricate epitaxial NaAlO2 and £^-Al2O3 nanopartricles for electron microscopic and spectroscopic characterizations. The NaAlO2 phase (denoted as N), presumably derived from NaAlO2 .5/4H2O, was found to form intimate intergrowth with the £^-Al2O3 following a specific crystallographic relationship [211]£^//[110]N; ( 2 22) £^//(002)N and (0 2 2) £^//(110)N for a parallel close packed planes in terms of corner linked AlO4 tetrahedra and a beneficial lower interfacial energy and/or strain energy. The composite phases have significant internal compressive stress up to 7 and 40 GPa according to cell volume and IR shift results and a low minimum band gap of 5.9 eV for potential applications in UV region.

Glyphosate (N-(phosphonomethyl)glycine, PMG, H3L) is a widely used organophosphorous herbicide. It interacts with metal ions and mineral surfaces, which may affect its mobility, degradation and bioavailability in the environment. However, these interactions are far from fully understood. This thesis is a summary of five papers discussing the complexation of PMG with metal ions in aqueous solution and the adsorption of PMG and/or Cd(II) on different mineral surfaces. The complexation of PMG with the metals Cd(II) or Al(III) in aqueous solution was investigated with macroscopic and molecular scale techniques. Potentiometric titration data were combined with EXAFS, ATR-FTIR and NMR spectroscopic data to generate solution equilibrium models. In the PMG-Cd(II) system, only mononuclear complexes were formed, while both mono and binuclear complexes were observed in the PMG-Al(III) system. EXAFS, ATR-FTIR, and XPS measurements showed that PMG adsorbs to the surfaces of goethite (α-FeOOH), aged γ-alumina (γ-Al2O3) and manganite (γ-MnOOH) through one oxygen of its phosphonate group to singly-coordinated surface sites. Surface complexation models consistent with these spectroscopic results were fit to adsorption data using the 1pK reaction formalism. Electrostatic effects were accounted using either the Extended Constant Capacitance Model (ECCM) or the Basic Stern Model (BSM), and the charge of the surface complexes was distributed over the different planes. The formation of the surface complexes was described according to the following reactions: ≡MeOH(0.5-) + H3L <=> ≡MeHL(1.5-) + H2O + H+ ≡MeOH(0.5-) + H3L <=> ≡MeL(2.5-) + H2O + 2H+ The coadsorption of PMG and Cd(II) on the surfaces of goethite and manganite results in the formation of ternary mineral-PMG-Cd(II) surface complexes, as suggested from EXAFS results. Previous EXAFS measurements have also established the coordination geometries for the binary goethite-Cd(II) and manganite-Cd(II) surface complexes. In addition to the surface reactions in the binary mineral-Cd(II) and mineral-PMG systems, a single ternary complex with the stoichiometry ≡MeLCd(OH)(1.5-) was sufficient to explain coadsorption data: ≡MeOH(0.5-) + H3L + Cd2+ <=> ≡MeLCd(OH)(1.5-) + 3H+ It was concluded that the affinity of PMG for the three mineral systems decreases within the series: goethite > aged γ-Al2O3 > manganite. The formation of the ternary surface complex is more significant on goethite surfaces than on manganite surfaces.