Raman Microscopy of Selected Autunite Minerals

Raman spectroscopy at ambient and liquid nitrogen temperature has been used to determine the molecular structure of selected minerals from the autunite and meta-autunite groups. Six hydroxyl stretching bands for autunite are observed of which three are highly polarised. The hydroxyl stretching vibrations are related to the strength of hydrogen bonding of the water units. Bands in the Raman spectrum of autunite at 998, 842 and 820 cm–1 are highly polarised. Low intensity band at 915 cm–1 is attributed to the 3 antisymmetric stretching vibration of (UO2)2+ units. The band at 820 cm–1 is attributed to the 1 symmetric stretching mode of the (UO2)2+ units. The (UO2)2+ bending modes are found at 295 and 222 cm–1. The presence of phosphate and arsenate anions and their isomorphic substitution are readily determined by Raman spectroscopy. The collection of Raman spectra at 77 K enables excellent band separation

Synthesis and vibrational spectroscopic characterisation of synthetic hydrozincite and smithsonite

Hydrozincite and smithsonite were synthesised by controlling the partial pressure of CO2 . Previous crystallographic studies concluded that the structure of hydrozincite was a simple one. However both Raman and infrared spectroscopy show that this conclusion is questionable. Multiple bands are observed in both the Raman and infrared spectra in the (CO3)2-antisymmetric stretching and bending regions of hydrozincite showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the hydrozincite structure. Multiple OH stretching vibrations centred in both the Raman and infrared spectra show that the OH units in the hydrozincite structure are non-equivalent. The Raman spectrum of synthetic smithsonite is a simple spectrum characteristic of carbonate with Raman bands observed at 1408, 1092 and 730 cm-1. The symmetry of the carbonate anion in hydrozincite is C2v or Cs. This symmetry reduction results in multiple bands in both the symmetric stretching and bending regions. The intense band of hydrozincite at 1062 cm-1 is assigned to the ν1 (CO3)2- symmetric stretching mode. Three Raman bands assigned to the ν3 (CO3)2- antisymmetric stretching modes are observed for hydrozincite at 1545, 1532 and 1380 cm-1. Multiple infrared or Raman bands are observed in 800 to 850 cm-1 and 720 to 750 cm-1 regions and are attributed to ν2 and ν4 bending modes confirming the reduction of the carbonate anion symmetry in the hydrozincite structure. A Raman band for hydrozincite at 980 cm-1 is attributed to the δ OH deformation mode

Observation of Baryon Number Violation via Cold Neutron Sources

Current models describing the fundamental nature of the universe suggest that Baryonnumber need not be conserved and would provide a valid argument as to the levelof matter-antimatter imbalance in the observable universe. The observation of anyneutron/antineutron or neutron/mirror-neutron oscillations would confirm BaryonNumber Violation (BNV), and thus reveal the fundamental nature of the universe.Experiments that would show the existence of such oscillations, or at least put anupper limit on their time constants, are unique. A push to further investigate thesephenomena would either discover a phenomenon that gives rise to the existence of theuniverse as we know it, or narrow the wide field of theories that attempt to explainthese Beyond Standard Model mechanisms. New experiments utilizing sources of coldneutrons such as a nuclear reactor or spallation source provide a means by which tosearch for these higher energy scale phenomena beyond that which can be achievedwith a collider. Contemporary experiment design utilizing these sources in addition tomodern neutron transport techniques can provide an improvement in experimentalsensitivity upwards of three orders of magnitude beyond what as been attemptedpreviously. However, these designs utilize a range of technologies that have notnecessarily been implemented in such a grand manner. This practical implementationis a concern that further complicates the overall design. Demonstrations of noveltransport concepts and simulations incorporating those results into the developmentof an experiment design to observe this type of oscillation are the main focus of thiswork. The developments have also been my main contribution to the collaborativeeffort towards the realization of a new experiment that would meet move thisendeavour forward

Resin transfer moulding: Novel fabrics and tow placement techniques in highly loaded carbon fibre composite aircraft spars

A BAE Systems /UK EPSRC funded project Flaviir, is investigating the design and manufacture of low cost carbon fibre composite airframe structures. Novel binder coated unidirectional fibre tapes and tows were developed to enable the design of optimised primary structures. The RTM technique was applied to mould net shape sections of spar components. Various designs of wing attachment lugs were manufactured with a range of reinforcement materials, including non crimp fabric, novel binder coated tapes and conventional unidirectional prepreg. Alongside these, a novel technique termed optimised tow lay up (OTL) was used to reduce the weight. Binder coated carbon fibre tow is placed around the structure in the principal stress directions to increase both bearing strength and overall component stiffness. The novel materials, manufacturing technique and initial element test results are presented

Thermal Decomposition of Synthetic Argentojarosite - Implications for Silver Production in Medieval Times

The thermal decomposition of argentojarosite has been studied by thermogravimetric, spectroscopic and infrared emission techniques. Dehydroxylation occurs in three stages at 228, 383, 463 degrees Celsius with the loss of 2, 3 and 1 hydroxyl units. Loss of sulphate occurs at 548 degrees Celsius and is associated with a loss of oxygen. At 790 degrees Celsius loss of oxygen only leaves metallic silver and hematite. Changes in the structure of argentojarosite are also followed by the infrared emission spectra. The intensity of hydroxyl stretching vibration approaches zero by 400 degrees Celsius confirming the loss of hydroxyl units by this temperature. At this temperature changes in the infrared spectra of the sulphate units occurs. The intensity of the sulphate stretching vibrations approaches zero by 750 degrees Celsius. Thermal decomposition of argentojarosite is important in understanding silver production in ancient and medieval times. This work shows that temperatures of around 750 degrees Celsius are required to produce metallic silver