Thesis (doctoral)--Westfälischen Wilhelms-Universituat Münster, 1933.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvii, 163 p.; also includes graphics (some col.) Includes bibliographical references (p. 149-163). Available online via OhioLINK's ETD Center

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Proefschrift Universiteit Maastricht. / Met lit. opg., bibliogr. - Met samenvatting in het Nederlands.

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In the experiments detailed in this thesis, a series of scattering experiments were conducted in a versatile scattering chamber. In order to conduct these experiments, various electronic equipment was designed and built, including new computer controlled electron analyser power supplies. This new equipment was tested, adopted in this work, and is described in this thesis. The superelastic scattering technique was used on magnesium atoms to obtain a set of atomic collision parameters (ACPs), which describe the interaction. This was achieved by exciting a beam of magnesium atoms to the 3(1)P(1) excited state using resonant laser radiation around 285 nm, and using an electron beam with well defined momentum to de-excite the atoms. The momentum of the outgoing electrons was measured as the polarisation and scattering angle were varied, to obtain the ACPs. These measurements were carried out over an angular range of 30 degrees to 120 degrees and with incident energies equivalent to 35 eV, 40 eV, 45 eV, and 55 eV. A set of theoretical data was compared to the experimental results and found to be reasonably accurate at describing the interaction. Laser-aligned and ground-state (e,2e) ionisation measurements were taken from the 4(1)S(0) and 4(1)P(1) states of calcium. The measurements were taken with the energy of the scattered and ejected electrons set at 30 eV, and with one outgoing electron angle set to 45 degrees. The differential cross section was determined for a range of angles of the second electron, ranging from 30 degrees to 65 degrees. The incident and outgoing electron momenta were all defined in the same plane with the laser polarisation being in a plane perpendicular to the incident electron. The laser aligned (e,2e) measurements were compared to two theoretical models, one of which (a 3DW model) predicted an identically zero cross section when the laser polarisation was perpendicular to the scattering plane. The other model (a TDCC model) predicted a non-zero cross section, in agreement with the experiment. Simultaneous time-resolved two-colour photoionisation from the 5(2)P(3/2) and 6(2)P(3/2) states of rubidium was also conducted. These experiments investigated two pathways to creating 0.36 eV photoelectrons from rubidium. Photoelectrons were produced by either using laser radiation at ~780 nm to resonantly excite atoms to the 5(2)P(3/2) state followed by laser radiation at ~420 nm to ionise the atoms, or laser radiation at ~420 nm was used to resonantly excite atoms to the 6(2)P(3/2) state followed by radiation at ~780 nm which then ionised the atoms. Ionisation differential cross sections were measured over a full 360 degrees by rotating the laser polarisation vectors. By selectively detuning the laser beam so as to select individual ionisation pathways, and then by tuning both lasers to resonance, quantum interferences between the pathways that lead to ionisation were observed.

Agricultural soil properties exhibit variation over field plot scales that can ultimately effect the yield. This study performs multiple spatial pattern analyses in order to design spatially dependent regression models to better understand the interaction between these soil properties. The Cation Exchange Capacity (CEC) and Calcium-Magnesium Ratio (CaMgR) are analyzed with respect to Calcium, Magnesium, and soil moisture values. The CEC and CaMgR are then used to determine impact on the yield values present for the field. Results of this study show a significant measure of model parsimony (0.979) for the Geographically Weighted Regression (GWR) model of the CEC with free Ca, Mg, and soil moisture as explanatory variables. The model for CaMgR using the same explanatory variables has a much lower measure of model fit. The yield model using the CEC and CaMgR as explanatory variables is also low, which is representative of the underlying processes also impacting yield.

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A comprehensive study was conducted on the effects of de-icer and anti-icer chemicals on cement-based materials. Portland cement mortars and concretes were exposed to over 16 chloride-based and non-chloride-based generic and commercial products and changes in cement-based material properties were measured. Deleterious chemical actions of several types of these products on cement-based materials were observed, departing from the well-known position that attributes the concrete damage from such salts mainly to physical actions under freezing and thawing exposure. Independent of freezing and thawing exposure, mortars and concretes exposed to concentrated calcium chloride and magnesium chloride solutions were found to undergo severe deterioration whereas those exposed to sodium chloride did not. The mechanisms of deterioration are complex with factors such as concentration, temperature, and availability of calcium hydroxide playing important roles. It was found that the formation of calcium oxychloride of the form 3Ca(OH)2.CaCl2.12H2O, and the 3- and 5-form magnesium oxychloride, 3Mg(OH)2.MgCl2.8H2O and 5Mg(OH)2.MgCl2.8H2O, were the main causes for the severe deterioration, and to a lesser extent brucite, gypsum, and magnesium silicate hydrate (M-S-H). The instability of these oxychloride compounds when subjected to conditions normally encountered in sample preparation is suggested as the reason why field investigations have failed to relate distressed concrete to chemical attack by such de-icer and anti-icer chemicals. Concentrated solutions of calcium magnesium acetate were also found to be harmful to cement-based materials by dissolution of calcium hydroxide and formation of calcium acetate hydrate, whereas low concentrated solutions tended to cause slow deterioration by magnesium attack forming brucite, gypsum, and M-S-H. Potassium acetate chemicals did not cause significant deterioration in mortars when these products were diluted (25% by mass), but undiluted products (50% by mass) caused considerable distress in concrete specimens. The combined effect of chemical attack impairing concrete mechanical properties and subsequent salt scaling damage was proposed as the most likely mechanisms of field deterioration.

Optimum detergent dosage during a washing process depends on water quality, degree of pollution and quantity of laundry. Particularly, water quality is an important factor. Other parameters like carbonate- or non-carbonate hardness and calcium / magnesium (Ca / Mg) ratio in addition to total hardness of water have an impact on the amount of detergent. This work discusses the possibilities realizing a detergent sensor that measures important parameters for the washing process and assess the ideal necessary amount of detergent during the washing process. The approach is to combine impedance spectroscopy with cyclic voltammetry in order to determine both water quality and concentration of detergent in the suds which build up the basis for an optimum detergent dosage. The results of cyclic voltammetry show that it is possible to identify the Ca / Mg ratio and the carbonate hardness separately, which is necessary for the optimization of the washing process. Impedance measurements identify total hardness and detergent concentrations.