Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra. Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR. Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined. An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values. Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.

This dissertation attempts to extend the classes of halogen-containing systems which may be studied using solid-state nuclear magnetic resonance (SSNMR). As line shape broadening due to the quadrupolar interaction (QI) scales inversely with the applied field, high-field magnet technology is indispensable for this research. Combining advanced radiofrequency pulse sequences with high-field wideline data acquisition allowed for the collection of very broad SSNMR signals of all quadrupolar halogen nuclei (i.e., 35/37Cl, 79/81Br and 127I) within a reasonable amount of experimental time. The initial systems for study were of the MX2 variety (M = Mg, Ca, Sr, Ba; X = Cl, Br, I). In total, 9 anhydrous compounds were tested. The effects of hydrate formation were tested on 7 additional compounds. Systematic trends in the observed δiso values (and to a lesser extent, Ω and CQ) were found to be diagnostic of the extent of hydration in these materials. Resolving power was successfully tested using SrBr2, which possesses 4 magnetically unique sites. The composition of CaBr2•xH2O was convincingly determined using SSNMR data and the hydration trends noted above. The sensitivity of the QI to the local bonding environment (e.g., bond distance changes of less than 0.05 Å) was used to refine (when coupled with gauge-including projector augmented-wave density functional theory (GIPAW DFT) quantum chemical computations) the structure of MgBr2, and was used to correct prior NMR data for CaCl2 (earlier accounts had been performed upon a CaCl2 hydrate). During NMR data analysis of certain iodine-containing materials, it was found that standard fitting software (which uses perturbation theory) could not reproduce the observations. Proper analysis required the use of exact simulation software and allowed for the observation of high-order quadrupole-induced effects (HOQIE). This motivated further studies using rhenium-185/187 nuclei, where it was expected that HOQIE would be more dramatic. The observed rhenium SSNMR spectra possessed additional fine structure that had never been observed before experimentally, nor would be expected from currently-available perturbation theory analysis software. Lastly, preliminary results are shown where 127I SSNMR is used to study important supramolecular systems, and the composition of the popular synthetic reagent ‘GaI’ is elucidated.

This thesis has two major objectives. The first objective is to investigate the seasonal and diurnal variations in occurrence of HF coherent echoes. We assess F-region echo occurrence rates for the PolarDARN HF radars at Inuvik (INV) and Rankin Inlet (RKN) and the auroral zone SuperDARN radars at Saskatoon (SAS) and Prince George (PGR) for the period of 2007-2010. We show that the INV and RKN PolarDARN radars show comparable rates of echo occurrence all the time and they detect 1.5-2.5 times more echoes through ½-hop propagation mode (MLATs=80°-85°) than the SAS and PGR SuperDARN radars through 1½-hope propagation mode (MLATs=75°-80°). For all four radars, the winter occurrence rates are about ~2 times higher than the summer rates. For observations in the dusk, midnight and dawn sectors, equinoctial maxima are evident. The pattern of echo occurrence in terms of MLT/season is about the same for all radars with clear maxima near noon during winters and summers and enhanced (as compared to other time of the day) occurrence rates during equinoctial dusk and dawn hours. Additionally, to investigate the effect of solar cycle on occurrence of F-region echoes, we consider the near noon and near midnight echo occurrence rates for the Saskatoon radar over the period of 1994-2010. We show that there is a strong, by a factor of ~10, increase in SAS night-side echo occurrence towards solar maximum. The effect does not exist for the dayside echoes; moreover, a decrease in number of echoes, by a factor of ~2, was discovered for the declining phase of the solar cycle. The second objective is to evaluate the electron density and the electric field as factors controlling the occurrence of F-region echoes. We use observations of these two ionospheric parameters measured by CADI ionosonde and RKN observations of echo occurrence rates over Resolute Bay (MLAT=83°). We show that there is a correlation in changes of echo occurrence and electron density changes for 3 years of radar-ionosonde joint operation (2008-2010). The comparison of radar-ionosonde data shows that the enhanced echo occurrence at near noon hours during summer months correlate with the enhanced electric field during these periods.

Chlorine solid-state nuclear magnetic resonance (SSNMR) is an ideal site specific probe of chloride-containing solids as SSNMR tensor properties are sensitive to the local chlorine environment. In this thesis, the development and use of chlorine SSNMR as a method to characterize a wide variety of chemical environments was explored. Ultrahigh field, and multi-field studies were essential to overcome the difficulties associated with the collection of chlorine SSNMR spectra. Benchmark chemical shift (CS) and electric field gradient (EFG) tensor data were collected for organic chloride systems, including several amino acid hydrochlorides. These experiments demonstrated the sensitivity of chlorine SSNMR to slight changes in chemical environment. Quantum chemical calculations were used to complement experimental data, with the gauge-including projector augmented wave DFT (GIPAW-DFT) method shown to yield better agreement than B3LYP or RHF methods. The GIPAW-DFT method was found to slightly, but systematically, overestimate the chlorine quadrupolar coupling constant and the CS tensor span. Other organic chlorides examined by chlorine SSMR included a known ion receptor, meso-octamethylcalix[4]pyrrole. This compound was found to have a very small quadrupole interaction (QI), but significant chemical shift anisotropy (CSA). GIPAW-DFT calculations were also utilized and, in combination with the experimental results, used to identify the solvate structure of the material analyzed by NMR. Chlorine SSNMR was further used to study different solvate structures and polymorphism. The technique was an effective means to distinguish different room temperature polymorphs of benzidine hydrochloride, despite the similarities of the chloride environments. In the case of magnesium chloride, chlorine SSNMR was sensitive to the level of hydration and through the use of GIPAW-DFT calculations, the identity of an unknown hydrate was determined. An analysis of several group thirteen chlorides demonstrated that chlorine SSNMR was also capable of characterizing the chlorine environment in cases where the QI is large, despite the resulting broad line widths. In these systems GIPAW-DFT calculations also yielded excellent agreement with experimental values. Throughout this research, chlorine SSNMR has been shown to be a useful and effective means to study both organic and inorganic chlorides, with computational methods proving to be an important complement to experimental data.

This dissertation attempts to extend the classes of halogen-containing systems which may be studied using solid-state nuclear magnetic resonance (SSNMR). As line shape broadening due to the quadrupolar interaction (QI) scales inversely with the applied field, high-field magnet technology is indispensable for this research. Combining advanced radiofrequency pulse sequences with high-field wideline data acquisition allowed for the collection of very broad SSNMR signals of all quadrupolar halogen nuclei (i.e., 35/37Cl, 79/81Br and 127I) within a reasonable amount of experimental time. The initial systems for study were of the MX2 variety (M = Mg, Ca, Sr, Ba; X = Cl, Br, I). In total, 9 anhydrous compounds were tested. The effects of hydrate formation were tested on 7 additional compounds. Systematic trends in the observed δiso values (and to a lesser extent, Ω and CQ) were found to be diagnostic of the extent of hydration in these materials. Resolving power was successfully tested using SrBr2, which possesses 4 magnetically unique sites. The composition of CaBr2•xH2O was convincingly determined using SSNMR data and the hydration trends noted above. The sensitivity of the QI to the local bonding environment (e.g., bond distance changes of less than 0.05 Å) was used to refine (when coupled with gauge-including projector augmented-wave density functional theory (GIPAW DFT) quantum chemical computations) the structure of MgBr2, and was used to correct prior NMR data for CaCl2 (earlier accounts had been performed upon a CaCl2 hydrate). During NMR data analysis of certain iodine-containing materials, it was found that standard fitting software (which uses perturbation theory) could not reproduce the observations. Proper analysis required the use of exact simulation software and allowed for the observation of high-order quadrupole-induced effects (HOQIE). This motivated further studies using rhenium-185/187 nuclei, where it was expected that HOQIE would be more dramatic. The observed rhenium SSNMR spectra possessed additional fine structure that had never been observed before experimentally, nor would be expected from currently-available perturbation theory analysis software. Lastly, preliminary results are shown where 127I SSNMR is used to study important supramolecular systems, and the composition of the popular synthetic reagent ‘GaI’ is elucidated.

The efficiency of an organic photovoltaic cell depends mainly on its morphology where an exciton has to migrate to a p-n junction to create a photocurrent. Therefore the distance from the bulk of the cell to a junction interface should not exceed the diffusion length of the exciton. In this thesis, two novel lithographical methods, to produce specific polymer morphologies, were developed and evaluated. In the first method, called embedded annealing, self-assembled polystyrene colloids were embedded in a polydimethylsiloxane (PDMS) film and annealed under an electric field to produce a bi-polymer structure consisting of polymer columns in a thin film of PDMS. Polymer colloids were successfully assembled into two dimensional hexagonally close packed arrays. However, the annealing process was unsuccessful. The second method, imprint annealing, aimed to increase the aspect ratio (height/width) of thermally imprinted micrometer sized polystyrene features by annealing them in uniform electric fields. The results showed that the aspect ratio of imprinted features can be significantly increased, 21-fold, while maintaining the periodicity of the original imprint. This is in contrast to previous results where smooth polymer films annealed in uniform fields where the periodicity of the resulting structures cannot be independently controlled, and are highly sensitive to the electrode spacing. Feature sizes down to 1 µm and aspect ratios up to 4.5 were achieved using imprint annealing. / Verkningsgraden hos en hos en solcell beror, för givna material, framförallt på dess uppbyggnad. För att bidra till fotoströmmen måste en genererad exciton vandra till en pn-övergång. På grund av detta bör det längsta avståndet till närmaste pn-övergång i solcellen inte vara längre än excitonens diffusionslängd. I detta examensarbete testas två olika litografiska metoder för att åstadkomma en specifik filmgeometri lämpad för organiska solceller. Den första metoden, kallad embedded annealing, går ut på att bädda in spontant ordnade sfäriska polystyrenkolloider i en polydimetylsiloxan (PDMS) -film för att sedan vid förhöjd temperatur applicera ett elektiskt fält över filmen. Förhoppningen var att på detta sätt töja ut kolloiderna till pelare genom PDMS-filmen. I det första steget ordnades kolloiderna sponant i tätpackade hexagonala tvådimensionella gitter på kiselsubstrat. Experimenten lyckades inte med hjälp av elektriska fält töja ut kolloiderna. Den andra metoden, imprint annealing, syftar till att öka höjd/bredd -förhållandet och minska diametern hos präglade polystyrenstrukturer. Dessa ursprungliga topografiska stukturer skapas med hjälp av en tryckpressmetod kallad nanoimprinting. Dessa strukturer värmdes upp, och ett uniformt elekrisk fält applicerades över dem. Mina resultat visar att man med elektriska fält avsevärt kan öka höjd-breddförhållandet hos polymerstrukturer och samtidigt bevara periodiciteten hos de ursprungliga strukturerna. Detta står i kontrast mot tidigare resultat på släta filmer, där periodiciteten inte kan kontrolleras oberonde av andra parametrar. Med imprint annealing ökades höjd-breddförhållandet hos enskilda strukturer upp till 21 gånger. Diametrar ner till 1 µm och höjd/breddförhållanden upp till 4,5 uppnåddes.

ABSTRACT EFFECTIVENESS OF CONCEPTUAL CHANGE INSTRUCTION ON OVERCOMING STUDENTS&#039 / MISCONCEPTIONS OF ELECTRIC FIELD, ELECTRIC POTENTIAL AND ELECTRIC POTENTIAL ENERGY AT TENTH GRADE LEVEL VATANSEVER, Orhan MS, Department of Secondary Science and Mathematics Education Supervisor: Dr. Mehmet Sancar December 2006, 107 pages The purpose of this study was to investigate the effectiveness of the conceptual change text based instruction over traditionally designed physics instruction to overcome tenth grade students&amp / #8217 / misconceptions on electric field, electric potential and electric potential energy concepts. To provide conceptual change, conceptual change texts (CCT) were developed by the researcher. An Electric Potential and Electric Potential Energy Concept Test (EPEPECT) which consists of 10-items was developed and used to examine students&amp / #8217 / probable misconceptions. Physics Attitude Scale (PATS) was administered to the students to obtain valid information concerning how conceptual change text based instruction effect students&amp / #8217 / attitudes toward physics. The subjects of this study included two tenth grade level classes from TED Ankara College Private High School in Ankara, Turkey, and a total of 37 students&amp / #8217 / scores were used for the statistical analysis. Students from one of the classes that were randomly assigned participated in traditional instruction and referred as the control group. Students from the other class participated in CCT based instruction and referred as the experimental group. EPEPECT and PATS had been administrated to both groups on two different occasions as pretest and posttest. According to the results of the study, statistically significant differences were found between conceptual change instruction and traditional method. Students taught with CCI showed a better scientific conception related to electric field, electric potential and electric potential energy and elimination of misconceptions than the students taught with traditionally designed physics instruction (TDPI). However, CCI did not increase the students&amp / #8217 / attitudes toward physics as school subject more than TDPI did. That is, conceptual change instruction was not effective in improving positive attitudes toward physics.

The terms &lsquo / ground-probing radar&rsquo / , &lsquo / ground penetrating radar (GPR)&rsquo / , &lsquo / sub-surface radar&rsquo / or &lsquo / surface-penetrating radar (SPR)&rsquo / refer to various techniques for detecting and imaging of subsurface objects. Among those terms GPR is preferred and used more often. In this thesis, the depth and the position of the buried circular cylinder are determined by a GPR system which comprises of an optical fiber sensor (OFS). The system is a combination of OFS, GPR and optical communication link. In order to determine the depth and the position, first of all the electric field distribution at the OFS is obtained by integrating the Green&rsquo / s function over the induced current distribution. Those distributions are observed for different frequency and depth values. The voltages inside the distribution are measured by OFS. By changing the depth of the cylinder and the frequency of the system, various plots showing x axis displacement versus measured voltages are obtained. Those plots are related to interference fringe patterns. The position and the depth of the cylinder are obtained using interference fringe patterns. All of the studies mentioned are performed in MATLAB R2007b program. The noises of the system due to OFS are extracted using OPTIWAVE OPTISYSTEM 7.0 program. By adding those noises to the measured voltage values, the operating frequency of the system is observed.

We have presented a thorough experimental investigation of electroabsorption spectroscopy on quasi-one-dimensional organic molecular crystals such as PTCDA and MePTCDI vapor deposited thin films to clarify the involvement of the charge-transfer exciton in the lowest excited state. By a self-built experimental setup, two kinds of electroabsorption measurements, called "perpendicular" and "parallel" measurements, were conducted at room temperature in ambient air. The crystalline texture of PTCDA and MePTCDI thin film samples are characterized by X-ray diffraction measurements. Current-voltage, capacitance-frequency and capacitance-voltage measurements are performed to clarify the electric field distribution inside organic layers. The results from electrical measurements show that only under certain conditions (electroabsorption measurements with proDC bias), the perpendicular and parallel electroabsorption meaurements can be directly compared. The electroabsorption spectra of MePTCDI and PTCDA thin films can be interpreted by neither pure Frenkel exciton nor pure charge-transfer exciton model. Essential features of electroabsorption spectra of MePTCDI and PTCDA thin films can be understood by the the mixture of Frenkel and charge-transfer exciton model. However, there is still a discrepancy in the directional properties of electroabsorption signals between experimental results and modle calculations. This small discrepancy suggests that a full interpretation of electroabsorption spectra of quasi-one-dimensional organic molecular crystals needs further experimental and theoretical investigations.

No description available.