Quantitative multielemental analysis using Particle Induced X-ray Emission (PIXE) using 1 and 2 MeV proton bombardment on thin targets has been achieved. The method is based on the calculation of atomic ratios from experimentally determined relative x-ray efficiency curves. Sample preparation techniques involving digestion and homogenous deposition of samples and standards with a minimum of contamination have been investigated. The accuracy of the method has been evaluated using five standard reference materials obtained from the National Bureau of Standards. The elimination of bremsstrahlung associated with the charging effect of non-conducting samples in PIXE analysis has been accomplished using thin carbon foils in the beam path. Applications of the PIXE technique to studies on deep-sea ferromanganese nodules were performed. The utility of PIXE in the analysis of noduoles and in the following of the distribution of a large number of elements through the various stages of a processing scheme were demonstrated.

Graduation date: 1987

Photocopy of typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1978. / Bibliography: leaves 219-235. / Microfiche. / xiii, 311 leaves ill., maps

Anhydrous monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂ (Form I, Form II and Form 1(B)) and cadmium(II), Cd[H(C₆H₅)PO₂]₂ (Form I and Form II) were synthesized and characterized by solubility tests, Differential Scanning Calorimetry (DSC), Infrared Spectroscopy, X-ray Powder Diffractometry, Electron Spin Resonance (ESR) spectroscopy, magnetic susceptibility measurements and Electron Spectroscopy for Chemical Analysis (ESCA). These materials are considered to be polymeric with metal ions connected in chains by double bridging phosphinate groups with cross-linkage forming sheets and octahedral metal centers. Magnetic susceptibility studies showed that Mn[H(C₆H₅)PO₂]₂ (Form I) exhibits relatively strong antiferromagnetic exchange interactions (J is about -4.50 cm⁻¹) and the effects on this magnetic exchange of doping diamagnetic cadmium ions into the material have been investigated. A series of mixed metal phosphinates of the form Mn₁₋x Cdx [H(C₆H₅)PO₂]₂ (Form I) where x=0 to 1.00 were prepared and investigated. The effect of doping with cadmium is to break the infinite manganese(II) monophenylphosphinate chain into finite segments and to generate monomer impurities in odd numbered segments. As the extent of doping is increased the average chain length decreases and the fraction of monomer increases. In addition, the exchange coupling constant, J, was found to decrease (from -4.50 to -2.70 cm⁻¹) as the average chain length decreases. Mn[H(C₆H₅)PO₂]₂ (Form 1(B)), which is precipitated from concentrated solutions, contains much shorter chain fragments than the pure Form I material. Mn[H(C₆H₅)PO₂]₂ (Form II) has a distinct infrared spectrum and X-ray powder diffraction pattern and shows much weaker antiferromagnetic behavior (J is about -2.40 cm⁻¹) than the Form I compound. Magnetic studies suggest that in this compound the average chain length is significantly smaller than in Mn[H(C₆H₅)PO₂]₂ (Form I). The hydrated monophenylphosphinates of manganese(II), Mn[H(C₆H₅)PO₂]₂•H₂0 and Mn[H(C₆H₅)PO₂]₂•2H₂0, were synthesized and characterized in this work. The structures of these compounds are considered to be similar to those of the anhydrous materials except in the hydrated compounds one or two of the metal coordination sites are occupied by water molecules. The dihydrate shows only very weak antiferromagnetic properties (J is about -0.50 cm⁻¹). The diphenylphosphinates of manganese(II) and cadmium(II) were also prepared and characterized. The infrared spectra and X-ray powder diffraction patterns for these materials are distinct from each other,which indicates the compounds are not isomorphous. Only rather weak magnetic exchange was observed in the manganese compound. Zn[H(C₆H₅)PO₂]₂ has also been synthesized and partially characterized in this work. The infrared spectrum and X-ray powder diffraction pattern obtained for this compound are unique among all the metal phosphinates studied in this work. / Science, Faculty of / Chemistry, Department of / Graduate

Including porosity introduces absorption into the previously developed scattering analysis for elastic spheres. Acoustic propagation in porous media has two distinct compressional modes, one in which the fluid and the structure move in phase with each other and the other in which they move in opposite phase. Expressions for the complex wavenumbers of both waves are derived, using the parameters for manganese nodules. A modal analysis with a pressure boundary condition indicates that the first kind of compressional wave is lightly attenuated and carries most of the energy of the coupled system. The second compressional wave is highly attenuated and effectively loses all of its energy in the first centimeter of the nodule. This second wave is very important for consideration of nodule-scale dimensions since it represents the dominant loss mechanism. A method was developed to form a single effective compressional wave attenuation for both compressional waves by employing a pressure and velocity boundary condition at the surface of the nodule and using a spatially integrated intensity match. An effective wave attenuation is generated for the compressional wave in the non-porous elastic model which accounts for porous attenuation and which is based on a parameter defined as travel distance L. If L is assumed to be proportional to nodule radius, the attenuation is approximated as constant for the frequency range of interest and is independent of nodule radius. An effective attenuation is predicted. The shear attenuation is found to exhibit a frequency squared form dependence for manganese nodules. However, shear attenuation is very small for ideal nodules and is negligible compared to the compressional loss. The elastic model of the nodule was numerically altered to accommodate complex wavenumbers in shear and compression. Four distinct regions of attenuation are observed in individual reflectivity, R_θ, versus ka plots and discussed. The importance of including attenuation is readily apparent from observing the transformation of the elastic non-porous results. Scattering experiments were performed on manganese nodules and experimental individual reflectivity versus ka plots were generated. Good agreement is found for the spherical Atlantic nodules using values in the third region of attenuation. From these experiments, an estimation of attenuation is made and compared with the theoretical prediction. The influence of attenuation on individual scattering and multiple scattering is investigated. Attenuation tends to shift the major bottom reflectivity, C_R, peak toward lower ka values. This affects the prediction of the acoustic response of manganese nodule deposits. / Master of Science

Thesis (Ph. D.)--University of Bombay, 1969. / Includes bibliographical references (leaves 91-100).

A study of the mineralogy and major element geochemistry of ferromanganese crusts and nodules from the northeastern equatorial Pacific Ocean involved three inter-related projects: ft) the major element geochemistry of crusts and nodules from two study areas, (2) the development of a selective sequential extraction scheme (SSES) and a differential X-ray diffraction technique (DXRD) for the study of the mineralogy of the deposits, and (3) the application of the SSES and DXRD to a small population of crusts and nodules from the two study areas. The objectives of the first project were to relate the composition of the crust and nodule samples to the environment of formation as well as to the mineralogy which could be identified from a bulk powdered sample. The SSES was developed to determine the partitioning of Cu, Ni, and Co concentrations between the Mn and Fe oxides present in crusts and nodules. In developing a SSES, two goals had to be attained: (1) since crust and nodule samples are finite in size and numerous different analyses are to be preformed on a single sample, a SSES should be developed which uses as small amount of sample as feasible, and (2) develop a SSES which is as time efficient as possible. The development of the DXRD in conjuction with the SSES identified which Mn and Fe oxide mineral phase was responsible for hosting Cu, Ni, and Co. In developing the DXRD procedure two other goals had to be attained: (1) use of small leached samples, and (2) recovery of the sample aafter XRD analysis. The purpose of the third project was to test the two analytical procedures on a group of crust and nodule samples which have a wide range in compositions and oxide phase mineralogies. One group of hydrothermal nodules, from Survey Region B, was found to be enriched in Mn and depleted in Fe and Si. The Mn-rich mineral phases were identified as todorokite and birnessite. The second group of hydrothermal nodules, from Survey Region B, was found to be enriched in Fe and Si and depleted in Mn. The Fe-Si rich mineral phase was identified as iron-rich nontronite. Both groups of hydrothermal nodules were depleted in Co, Cu, and Ni. Dymond et al. (1984) and Chen & Owen (1989) identified one group of hydrothermal nodules located close to the East Pacific Rise (EPR) as being enriched in Fe but depleted in Mn, Cu, Ni, and Co. This composition agrees with the Fe-Si rich hydrothermal nodules identified in Survey Region B. Both Dymond et al. (1984) and Chen & Owen (1989), however, interpreted a second group of nodules, close to the EPR, which were enriched in Mn but depleted in Cu, Ni, and Co as suboxic diagenetic deposits. This group of nodules is the Mn-rich end-member composition of hydrothermal nodules identifed in this study. The composition of nodules from Survey Region B indicates there is a correlation between Co abundance and the proximity of the nodules to the hydrothermal discharge from the JEPR. Nodules that are Co-enriched are found farthest away from hydrothermal activity. In contrast, cobalt-depleted nodules coincide with known areas of hydrothermal activity. The SSES and DXRD was applied to a small population of crusts and nodules from the two Survey Regions. The DXRD patterns from the second stage of leaching on the crusts and nodules showed that the iron phase mineralogy in marine crusts and nodules is either akaganeite or ferrihydrite. The DXRD patterns from the second stage of leaching on the Mn-rich hydrothermal crusts and nodules, from Survey Region B, identified the Mn-bearing mineral hausmannite. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The theory of the scattering of plane waves in a fluid medium by an isotropic elastic sphere representing a manganese nodule is developed. Scattering cross sections were computed using the theory and the results are presented graphically. The scattering cross section and the reflectivity factor govern the characteristic acoustic signature of the Pacific where manganese nodules are present. Preliminary experimental data for the compressional and shear wave speeds in nodule material is given. This data was used in the scattering computations. Limiting cases of Rayleigh scattering and scattering from fixed rigid and fluid spheres are also shown for comparison. It is shown that the rigidity of the nodules dominates the high frequency response. The problem of the multiple scattering of acoustic waves by randomly distributed nodules on the flat ocean bottom is investigated analytically. The statistical description of nodule deposits is given. The concept of the configurational average is introduced in order to obtain the average scattered response. The size averaging is found to be able to smooth the acoustic response in the high frequency region. The plane wave analysis for the multiple scattering problem is justified by the narrow beam investigation. It shows that the beam effect on the average backscattered field can be neglected in the remote sensing. For a planar distribution of nodules, the average scattered field excited by a normally incident plane wave is verified to be plane waves characterized by coherent reflection and transmission coefficients. The multiple scattering effect is found to be a higher order correction to the average scattered field. For a sparse distribution of nodules, the average scattered field can be well evaluated using the single scattering theory in which the scattering process is also shown to be energy conserved. For a dense distribution of nodules, the radial distribution function is used in the Foldy-Lax hierarchy. The result shows that the pair correlation affects the phase of the second order correction term in the expression for the average scattered field when the higher order statistics are truncated using the quasi crystalline approximation. / Ph. D.