The kinetics and mechanism of the place exchange reaction(PER) of alkylthiols with alkylthiol-protected gold nanoparticles(AuNP) are investigated. Using chemically similar alkylthiols it was possible to study the reaction in the absence of perturbing factors, enabling detailed mechanistic and kinetic studies to be explored. It is found that the reactions are zero order in incoming ligand and overall follow a second order diffusion limited Langmuir rate law. In the case where there is little chemical distinction between the incoming and capping ligands, the reactions proceed to an endpoint consistent with a Keq=1. The rate of the reaction is dependent on the chain length of the capping ligand and the AuNP core size. The related dialkyldisulphide for-alkylthiol AuNP exchange reaction is consistent with the same rate law and also proceeds to a well-defined endpoint. However, the rate constant is 20-fold less than the alkylthiol case. These results lead to a convergent model of PERs where the rate limiting process involves both incoming and outgoing ligands, with diffusion of the incoming ligand to the AuNP surface as the major controlling factor of the reaction rate.

The Barry gold deposit is an example of an Archean greenstone-hosted lode gold deposit located in the Urban-Barry greenstone belt in the Abitibi subprovince of Québec, Canada. Auriferous zones are spatially associated with NE-trending ductile shear zones with moderate south-easterly dip. Gold mineralization occurs within albite-carbonate-quartz veins that are straight N64ºE/64ºSE and folded N20ºE/60ºSE and within the surrounding carbonate-quartz-pyrite and locally biotite-carbonate alteration zones of the host mafic volcanic rocks. The deposit has gold resources indicated at 52,300 oz (385,000 mt at 4.23 g/t Au) and inferred at 126,600 oz (966,000 mt at 4.07 g/t Au). The host mafic volcanic rocks are part of the 2717 Ma Macho Formation that exhibit a geochemical signature transitional between mid-ocean and island arc. They are cut by pre-ore diorite, pre- and post-ore quartz-feldspar porphyry (QFP), and quartz monzonite dikes and plugs interpreted to have formed in a volcanic arc to syn-collisional setting. The auriferous veins comprise 5-15% volume of the mafic volcanic rocks, are 1-5cm wide, and locally pinch and swell or are boudinaged. Although the volcanic units strike N55-60ºE and dip 40ºSE, the ore envelope (>2 g/t Au) is constrained from surface to 30m depth in an antiformal shape. Free gold is found in albite-carbonate-quartz veins, syn-mineralization altered host rocks, and locally within quartz veins cutting early QFP dikes. The timing of gold mineralization at the Barry deposit is well constrained by U-Pb zircon dating of pre-mineralization diorite and post-mineralization QFP dikes. Analyses of single zircon grains by thermal ionization mass spectrometry (TIMS) give concordant and overlapping data with indistinguishable ages, yielding an average age of 2697 ± 0.6 Ma that is interpreted as the age of gold mineralization at the Barry deposit. This date indicates that gold mineralization was coeval with regional deformation and magmatism, and is, to our knowledge, the most precise age yet established for Archean lode gold mineralization. This confirms that the Barry lode gold deposit formed during an earlier, pre-2686, deformational period in the late Archean, similar to what was documented in the Kiena, Norlartic and Siscoe (Main Zone) mines in the Southern Abitibi greenstone belt. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-05-12 17:18:25.925

No description available.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Political Science. / Typescript. Includes bibliographical references (leaves 299-323). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19782

Thesis (M.S.)--University of Michigan, 1968.

Thesis (M.S.)--University of Michigan, 1960.

Thesis (doctoral)--Tübingen, 1935.

Thesis (M.S.)--University of Michigan, 1960.

Thesis (M.S.)--University of Michigan, 1968.

Thesis (M.Communication Pathology)--Universiteit van Pretoria, 2002. / Summary in English and Afrikaans. Includes bibliographical references.