The ultimate goal of this project was to improve the sensitivity and detection limits of inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) and then apply it to the speciation analysis of As. To this end, two approaches were taken: the use of organic modifiers and that of a pre-evaporation interface between the spray chamber and the plasma torch. The radial profiles of some background ions and analytes in three different matrices (1% HNO3, 1% HNO3 with 2% v/v methanol, 1% HNO3 with 0.2% m/v sodium dodecylsulfate (SDS)) were investigated in ICP-TOFMS. Although these concentrations of methanol and SDS induced the same increase (37%) in sample introduction efficiency, the change in analyte signal as a function of m/z followed opposite trends in these two matrices. The results show that matrix effects arising from different organic modifiers affected the distribution of ions in the plasma differently as a result of changes induced in the predominant ionisation mechanisms in the plasma. The effect of a pre-evaporation interface on the distribution of ions in ICP-TOFMS was also investigated by spatial profiling, which showed that the optimal axial position of all elements shifted closer to the load coil. Furthermore, the radial profiles became significantly narrower and Gaussian. The decrease of droplet size thus improved the sensitivity and detection limits for multi-elemental analysis. A further investigation of the effect of the pre-evaporation interface revealed that, for cationic analytes, the signal enhancement had an inverse dependency on analyte mass upon heating the interface. In the case of As, a signal enhancement upon heating the interface only resulted when concomitant ionic analytes were present or with a 0.01 M NaOH matrix. All these observations could be rationalised by changes in the number of Coulomb fission events occurring during pre-evaporation, which depend on the size and charge of droplets, as well as the identity and concentration of the matrix. Finally, the baseline separation of four As species by ion exchange liquid chromatography with detection by ICP-TOFMS and application of the pre-evaporation interface tube to As speciation were achieved using a mobile phase of NH4NO3, following an investigation of its matrix effects. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-07-12 13:51:55.115

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The physics of oil and petroleum evaporation are investigated. Literature on oil spill evaporation shows that most workers use boundary-layer equations adapted from water evaporation work. These equations predict a constant evaporation mass-transfer rate, dependent on scale size and wind speed. Evaporation was studied further by measuring evaporation of commercial oil products. An experimental apparatus for the study of evaporation was developed. Evaporation was determined by weight loss measured on a balance and recorded constantly on a computer. Examination of the data shows that most oil and petroleum products evaporate at a logarithmic rate with respect to time. This is attributed to the overall logarithmic appearance of many components evaporating at different linear rates. Petroleum products with fewer chemical components such as diesel fuel, evaporate at a rate which is square root with respect to time. The particular behaviour is shown to be a result of the number of components evaporating. Oils with greater than seven to ten components can be predicted with logarithmic equations, those with three to seven components, with square root equations. Evaporation of oils and petroleum products is not strictly boundary-layer regulated. This is largely a result of the high saturation concentrations of oil components in air, which is associated with a high boundary-layer regulated rate. Typical oil evaporation rates do not exceed that of molecular-diffusion, and thus turbulent diffusion does not increase the evaporation rates. Some volatile oils and petroleum products show some effect of boundary-layer regulation at the start of the evaporation process, but after several minutes, evaporation slows because of the loss of the more volatile components, at which point evaporation ceases to be boundary-layer regulated. Overall, boundary-layer regulation can be ignored in the prediction of oil and petroleum evaporation. A simple equation relating only the logarithm of t

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No description available.

In this project, thin films are being manufactured by different methods in a thin film deposition set-up and subsequently characterized. This is done in order to determine if the set-up is capable of producing films of sufficient quality to be used for research purposes in the ion physics group of the division of applied nuclear physics at Uppsala University. Both copper and silver films are manufactured by magnetron sputtering deposition. Copper films are also manufactured by evaporation deposition. Deposition is made on Si(001) substrates. The films are analyzed with Rutherford Backscattering Spectrometry (RBS) and Time of Flight- Elastic Recoil Detection Analysis (ToF-ERDA). Results show that the deposition rate of the set-up is much faster compared to the one provided by the manufacturer of the set-up. The purity of the films i.e. the concentrations of the contaminants are found to be in an acceptable range for research applications with an average oxygen contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?1.53%20%5Cpm%200.05%20%25" /> and carbon contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.53%20%5Cpm%200.02%20%25" /> for sputtered copper films. Sputtered silver films were found to have an oxygen contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.28%20%5Cpm%200.012%20%25" /> and a carbon contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.41%20%5Cpm%200.023%20%25" />. Evaporated copper films were found to have an oxygen contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.45%20%5Cpm%200.018%20%25" /> and carbon contamination of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.31%20%5Cpm%200.013%20%25" />. Traces of gold (<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cprec%200.5%20%25" />) were found exclusively in the sputtered films. Trace amounts of hydrogen could also be detected in both sputtered and evaporated films. The evaporated films are found to show lower contamination by oxygen than the sputtered films, but the manufacturing process employed in this study of evaporated films is not suitable to use for producing thin films of specific thicknesses as there is insufficient data to find a deposition speed. Overall, the set-up is capable of producing thin films with a sufficient quality for it to be used by the department when producing thin films for research. / I det här projektet produceras tunnfilmer med olika metoder i en uppställning för tunnfilmsdeposition och karaktäriseras sedan för att bedöma om maskinen är kapabel att producera filmer av tillräckligt bra kvalitet för att kunna användas i forskningssyften inom jonfysikgruppen på avdelningen för tillämpad kärnfysik på Uppsala Universitet. Både koppar och silverfilmer produceras med magnetronsputtring. Kopparfilmer produceras också med resistiv förångning. Deposition sker på Si(001)-substrat. Filmerna analyseras med Rutherford Backscattering Spectrometry (RBS) och Time of Flight- Elastic Recoil Detection Analysis (ToF-ERDA). Resultaten visar att depositionshastigheten för maskinen är snabbare än det som angetts av företaget som producerar maskinen. Renheten hos filmerna, dvs. koncentrationen av föroreningar, finnes vara inom en acceptabel nivå för forskningstillämpningar med en genomsnittlig syrekontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?1.53%20%5Cpm%200.05%20%25" /> och kolkontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.53%20%5Cpm%200.02%20%25" /> för sputtrade kopparfilmer. Sputtrade silverfilmer finnes ha en syrekontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.28%20%5Cpm%200.012%20%25" /> och en kolkontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.41%20%5Cpm%200.023%20%25" />. Förångade kopparfilmer finnes att ha en syrekontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.45%20%5Cpm%200.018%20%25" /> och en kolkontamination på <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?0.31%20%5Cpm%200.013%20%25" />. Spår av guld (<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cprec%200.5%20%25" />) hittades enbart i sputtrade filmer. Spår av väte kunde också hittas i både sputtrade och förångade filmer. De förångade filmerna finnes ha lägre syrekontamination än de sputtrade filmerna, men tillverkningsprocessen som används i projektet vid tillverkning av förångade filmer är inte lämplig att använda i produktion av tunnfilmer med specifika tjocklekar då det saknas data för att kunna hitta en depositionshastighet. Totalt sett är uppställningen kapabel att producera filmer av adekvat kvalitet för att de ska kunna användas inom avdelningen för produktion av filmer för forskning.

The stability of evaporating liquids is examined. The geometries investigated are semi-infinite liquid sheets, bounded liquid sheets, sessile droplets, and funnels. Stability parameters are generated to characterize the stability of evaporating semi-infinite liquid sheets, and bounded liquid sheets. The derivation is made possible by introducing evaporation as the specific heat transfer mechanism at the interface, and using the statistical rate theory expression for evaporation flux so there are no fitting parameters. It is demonstrated that a single parameter can be used to predict the onset criterion instead of two parameters. A linear stability analysis is performed for spherical sessile droplets evaporating on substrates constructed of either insulating or conducting materials. A stability parameter is generated to characterize the stability of sessile droplets evaporating on insulating substrates and conducting substrates. The results indicate that spherical sessile droplets evaporating on insulating substrates are predicted to transition to Marangoni convection. Since there are currently no experimental results to compare the theory with, another analysis is performed for liquids evaporating from funnels, which can be compared with existing experimental observations. A linear stability analysis predicts stable evaporation for funnels constructed of insulating materials, in contrast to the sessile droplet case, and generates a new stability parameter for funnels constructed of conducting materials. The stability parameter is free of fitting variables since the statistical rate theory expression for the evaporation flux is used. The theoretical predictions are found to be consistent with experimental observations for water evaporating from a funnel constructed of poly(methyl methacrylate) (PMMA) and for water and heavy water evaporating from a funnel constructed of stainless steel. A parametric analysis is performed on the new stability parameter for liquids evaporating from funnels constructed of conducting materials, indicating that smaller interfacial temperature discontinuities, higher evaporation rates, and smaller radii correspond to less stable systems. It is also illustrated that calculations using statistical rate theory predict an instability, which is consistent with experimental observations, whereas using the Hertz-Knudsen theory does not predict any instability.

The stability of evaporating liquids is examined. The geometries investigated are semi-infinite liquid sheets, bounded liquid sheets, sessile droplets, and funnels. Stability parameters are generated to characterize the stability of evaporating semi-infinite liquid sheets, and bounded liquid sheets. The derivation is made possible by introducing evaporation as the specific heat transfer mechanism at the interface, and using the statistical rate theory expression for evaporation flux so there are no fitting parameters. It is demonstrated that a single parameter can be used to predict the onset criterion instead of two parameters. A linear stability analysis is performed for spherical sessile droplets evaporating on substrates constructed of either insulating or conducting materials. A stability parameter is generated to characterize the stability of sessile droplets evaporating on insulating substrates and conducting substrates. The results indicate that spherical sessile droplets evaporating on insulating substrates are predicted to transition to Marangoni convection. Since there are currently no experimental results to compare the theory with, another analysis is performed for liquids evaporating from funnels, which can be compared with existing experimental observations. A linear stability analysis predicts stable evaporation for funnels constructed of insulating materials, in contrast to the sessile droplet case, and generates a new stability parameter for funnels constructed of conducting materials. The stability parameter is free of fitting variables since the statistical rate theory expression for the evaporation flux is used. The theoretical predictions are found to be consistent with experimental observations for water evaporating from a funnel constructed of poly(methyl methacrylate) (PMMA) and for water and heavy water evaporating from a funnel constructed of stainless steel. A parametric analysis is performed on the new stability parameter for liquids evaporating from funnels constructed of conducting materials, indicating that smaller interfacial temperature discontinuities, higher evaporation rates, and smaller radii correspond to less stable systems. It is also illustrated that calculations using statistical rate theory predict an instability, which is consistent with experimental observations, whereas using the Hertz-Knudsen theory does not predict any instability.

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No description available.