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Silicon photonics has become a key solution to tackle the demands on current communication systems and information processing because the use of this platform can reduce power consumption, eliminate electrical to optical conversion and leverage mature CMOS fabrication techniques. As silicon photonic devices are introduced into system-level applications, new challenges need to be addressed. This thesis will present some solutions to these challenges. These challenges range from device design and functionality to the post-processing and testing of silicon photonic devices. First, the system-level testing of a silicon photonic switch with crosstalk using real Ethernet datastreams is presented. Next, a rapid characterization technique for processing of silicon photoinc switches is shown. Finally, the functionality of barrel shifting is demonstrated in silicon photonics. The challenges and the solutions presented in this thesis are key steps to realizing the promise of system-level applications of silicon photonic devices.

Highlights • Predictable trace element enrichments and depletions in the Reykjanes system. • Boiling exerts a major influence on the enrichment of metals. • High concentrations of Au and Ag and Pb indicate accumulation in reservoir fluids. • Three quarters of the metal budget is deposited at depth or in the upflow zone. Abstract Mineral precipitation in the seawater-dominated Reykjanes geothermal system on the Mid-Atlantic Ridge, Iceland is caused by abrupt, artificially induced, pressure and temperature changes as deep high-temperature liquids are drawn from reservoir rocks up through the geothermal wells. Sulfide scales within these wells represent a complete profile of mineral precipitation through a seafloor hydrothermal system, from the deep reservoir to the low-temperature silica-rich surface discharge. Mineral scales have formed under a range of conditions from high pressures and temperatures at depth (>2 km) to boiling conditions in the upflow zone and at the surface. Consistent trace element enrichments, similar to those in black smoker chimneys, are documented: Cu, Zn, Cd, Co, Te, V, Ni, Mo, W, Sn, Fe and S are enriched at higher pressures and temperatures in the deepest scales, Zn and Cu, Bi, Pb, Ag, As, Sb, Ga, Hg, Tl, U, and Th are enriched at lower temperatures and pressures nearer to the surface. A number of elements (e.g., Co, Se, Cd, Zn, Cu, and Au) are deposited in both high- and low-pressure scales, but are hosted by distinctly different minerals. Other trace elements, such as Pb, Ag, and Ga, are strongly partitioned into low-temperature minerals, such as galena (Pb, Ag) and clays (Ga). Boiling and destabilization of metal-bearing aqueous complexes are the dominant control on the deposition of most metals (particularly Au). Other metals (e.g., Cu and Se) may also have been transported in the vapor phase. Very large enrichments of Au, Ag and Pb in the scales (e.g., 948 ppm Au, 23,200 ppm Ag, and 18.8 wt.% Pb) versus average concentrations in black smoker chimneys likely reflect that some elements are preferentially deposited in boiling systems. A mass accumulation of 5.7 t/yr of massive sulfide was calculated for one high-temperature production well, equating to metal fluxes of 1.7 t/yr Zn, 0.3 t/yr Cu, 23 kg/yr Pb, 4.1 kg/yr Ag, and 0.5 kg/yr Au. At least three quarters of the major and trace element load is precipitated within the well before reaching the surface. We suggest that a similar proportion of metals may be deposited below the seafloor in submarine hydrothermal systems where significant boiling has occurred. Mass accumulation estimations over the lifetime of the Reykjanes system may indicate significant enrichment of Zn, Pb, Au, and Ag relative to both modern and ancient mafic-dominated seafloor massive sulfide deposits, and highlights the potential for metal enrichment and accumulation in the deep parts of geothermal systems.

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Actively-forming modern seafloor massive sulfide (SMS) deposits are analogous to ancient volcanogenic-hosted massive sulfide (VMS) deposits which are major sources of Zn, Cu, Pb, Ag, and Au, and significant sources for Co, Sn, Se, Mn, Cd, In, Bi, Te, and Sb. Growing interest in the mining potential of major, trace, and critical metals in SMS deposits has not taken into account sub-seafloor mineralogical characterization which is crucial to the metal budgets. The majority of SMS samples are from the surface or very shallow-subsurface and trace element concentrations are not representative of the entire sub-seafloor deposit. A three-part approach in this thesis investigated the distribution and mineralogical residence of trace elements in sub-seafloor submarine hydrothermal systems, in order to understand metal budgets and determine whether the behaviour and residence of trace elements can be systematically predicted.

Actively-forming modern seafloor massive sulfide (SMS) deposits are analogous to ancient volcanogenic-hosted massive sulfide (VMS) deposits which are major sources of Zn, Cu, Pb, Ag, and Au, and significant sources for Co, Sn, Se, Mn, Cd, In, Bi, Te, and Sb. Growing interest in the mining potential of major, trace, and critical metals in SMS deposits has not taken into account sub-seafloor mineralogical characterization which is crucial to the metal budgets. The majority of SMS samples are from the surface or very shallow-subsurface and trace element concentrations are not representative of the entire sub-seafloor deposit. A three-part approach in this thesis investigated the distribution and mineralogical residence of trace elements in sub-seafloor submarine hydrothermal systems, in order to understand metal budgets and determine whether the behaviour and residence of trace elements can be systematically predicted. Aktive Massivsulfidvorkommen vom Meeresboden (SMS) gelten als moderne Analoga zu den sogenannten Vulkanit-gebundenen Massivsulfidvorkommen der Erdgeschichte, die wichtige Quellen für die Metalle Zn, Cu, Pb, Ag und Au sind sowie signifikante Mengen an Co, Sn, Se, Mn, Cd, In, Bi, Te und Sb enthalten. Das wachsende Interesse an dem Rohstoffpotential der rezenten Vorkommen in Bezug auf Haupt-, Spuren- und kritischen Metallen hat die mineralogischen Eigenschaften der unterhalb des Meeresbodens liegenden Zonen nicht berücksichtigt. Dabei sind diese Bereiche für die Abschätzung des Rohstoffpotentials wesentlich. Der bei Weitem größte Teil der modernen Massivsulfidproben stammt von der Meeresbodenoberfläche oder den Bereichen knapp darunter und ihre Metallgehalte sind für die tieferen Bereiche nicht repräsentativ. Durch einen dreiteiligen Ansatz soll in dieser Doktorarbeit die Verteilung und die mineralogische Kontrolle der Spurenelementzusammensetzung in den tieferen Bereichen rezenter Hydrothermalsysteme untersucht werden, um die Metallbudgets zu verstehen und um das Verhalten und das Vorkommen der Spurenmetalle in diesen Vorkommen systematisch vorherzusagen.

The distribution of trace ore elements in different paragenetic stages of pyrite has been documented for the first time in the sub-seafloor of the actively-forming TAG massive sulfide deposit. Trace element distributions have been determined by in-situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) of pyrite formed at different stages of mineralization, and at different temperatures constrained by previously published fluid inclusion analyses. The data reveal a strong dependence on paragenetic stage, with distinct low- and high-temperature enrichments. Porous pyrite (and marcasite) formed at low temperatures (350 °C) at the base of the hydrothermal mound and in the stockwork zone is enriched in Co, Se, Bi, Cu, Ni, and Sn. A number of different sub-types of pyrite also have characteristic trace element signatures; e.g., the earliest pyrite formed at the highest temperatures is always enriched in Co and Se compared to later stages. Ablation profiles for Co, Se, and Ni are smooth and indicate that these elements are present mainly in lattice substitutions rather than as inclusions of other sulfides. Profiles for As, Sb, Tl, and Cu can be either irregular or smooth, indicating both lattice substitutions and inclusions. Lead and Ag have mostly smooth profiles, but because Pb cannot substitute directly into the pyrite lattice, it is interpreted to be present as homogeneously distributed micro- or nano-scale particles. The behavior of the different trace elements mainly reflects their aqueous speciation in the hydrothermal fluids at different temperatures, and for some elements like Co and Se, strong partitioning into the pyrite lattice at elevated temperatures. Adsorption onto pyrite surfaces controls the distribution of a number of redox-sensitive elements (i.e., Mo, V, Ni, U), particularly in the upper part of the mound which is infiltrated by cold seawater. Where micro- or nano-scale inclusions of chalcopyrite, sphalerite, galena, or sulfosalts are present, there is still a strong temperature dependence on the inclusion population (e.g., more abundant chalcopyrite in the highest-temperature pyrite), suggesting that the inclusions were co-precipitated with pyrite rather than overgrown. However, at the deposit scale, the trace element distributions are also strongly controlled by remobilization and chemical zone refining, as previously documented in bulk geochemical profiles. The results show that pyrite chemistry is a remarkably good model of the chemistry of the entire hydrothermal system. For many trace elements, the concentrations in pyrite are highly predictive in terms of the conditions of mineral formation over a wide range of temperatures, from the stockwork zone to the cooler outer margins of the deposit. Calculated minimum concentrations of the trace elements in the fluids needed to account for the observed concentrations in pyrite show good agreement with measured vent fluid concentrations, particularly Pb, As, Mo, Ag, and Tl. However, significantly higher concentrations are indicated for Co (and Se) than have been measured in sampled fluids, confirming the strong partitioning of these elements into high-temperature pyrite.

Over the past three decades, a large number of seafloor hydrothermal vent sites and associated sulfide deposits have been discovered in the worlds' oceans. Geochemical analysis of samples collected from vent sites worldwide suggests that seafloor sulfide deposits may contain significant base and precious metal concentrations. The present study provides the first estimate of the global rare metal endowment of these deposits. It is shown that seafloor sulfide accumulations can contain elevated concentrations of the rare elements Bi, Cd, Ga, Ge, Hg, In, Mo, Sb, Se, Te, and Tl. Although these polymetallic deposits may represent a significant repository for some of these elements, the total endowment is regarded to be limited when compared to land-based ore deposits. Potential future deep-sea mining will not likely be a significant source of these metals.

The title complex, [Tb(C11H12N2O)6]I3, has essentially the same structure at 160 K as at room temperature, and is clearly centrosymmetric without any disorder, contrary to some proposals regarding the possible mechanism of tribolumin­escence. Terbium has an octahedral coordination and lies in a position of \overline 3 symmetry, with all six antipyrine ligands crystallographically equivalent. One iodide anion lies in a special position of site symmetry \overline 3, and another is on a threefold rotation axis, to give three iodide anions per terbium-centred complex cation.