Дисертації з теми "Electret studies"
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1
Graupner, Karola. "Dissociative electron attachment studies." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491947.
Повний текст джерелаАнотація:
The interaction of low energy electrons with stable and unstable molecules has been investigated with particular emphasis on negative ions formed in dissociative electron attachment. The experiment includes a trochoidal electron monochromator and a time-of-flight mass spectrometer. Measurements of dissociative electron attachment to HCCCN have been made inspired by the presence of this molecule in many extraterrestrial environments and by recent theoretical calculations of electron attachment to HCCCN. Two regions of electron attachment were observed with formation of CCCN- at 1.56 eV and CCCN-, CN-, HCC- and CC at - 5.30 eV where 2 II shape resonances were predicted to be located. Quantum chemical calculations performed in this work confirm these dissociation processes follow electron attachment into empty rr* orbitals. Negative ions were also observed at higher energies due to core excited resonances. Metastable dissociation of SF6-* has been observed in competition with autodetachment after attachment of close to 0 eV electrons to SF6. The lifetime of SF6-* has been estimated from the present measurements as a function of electron energy and hence, the internal energy of the anion. Metastable dissociation of a number of substituted benzene rings, such as dinitrobenzene, has also been investigated. This appears to be the first experimental study of the metastable decay of molecular anions with known internal energies. Measurements of dissociative electron attachment to the unstable CS and molecules have been performed to obtain total cross sections for dissociative electron attachment and characteristic negative ion mass spectra 'fingerprints'. CS forms S- at 5.43 eV, Cat - 6.40 eV and S- at - 6.70 eV. Dissociative electron attachment to CF2 was not observed, and an upper limit of the absolute cross section for the formation of F+CF has been deduced. A potential application of dissociative electron attachment measurements to plasma diagnostics is considered.
2
Love, Natalie Anne. "Studies of electron ionization." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1444953/.
Повний текст джерелаАнотація:
This thesis presents the results of experimental investigations to determine the electron ionization cross-sections of gases used in plasma etching processes. The small molecules studied include boron trichloride (BCI3), nitrous oxide (N20), sulphur hexafluoride (SF6) and acetylene (C2H2). The knowledge of accurate electron ionization cross-sections is essential for the modelling and optimization of plasmas used in industry and for the purposes of atmospheric modelling. It is therefore surprising that despite the widespread industrial use of these small molecules there have been few investigations of their ionization. It is the lack of available electron ionization cross-section data that provides the motivation for the investigations detailed in this thesis. The formation and dissociation of singly charged (monocations), doubly charged (dications) and triply charged molecular ions (trications) are studied using pulsed electron ionization (30-200 eV) coupled with time-of-flight (TOF) mass spectrometry and a two-dimensional (2D) ion coincidence technique. The experimental technique and data analysis procedures adopted allow the contribution to the total ion yield from single and multiple ionization to be distinguished and quantified. Such information yields relative partial ionization cross-sections (PICSs) and also allows relative precursor specific PICSs to be determined, which quantify the contribution from single, double and triple ionization to the relative yields of the fragment ions formed following electron-molecule collisions. Relative precursor specific PICSs therefore provide a more 'in-depth' chemical picture of each PICS. The relative precursor specific PICSs determined, following electron interaction with N20, provide clear evidence of energetic ion loss in previous cross-section determinations detailed in the literature. In addition, the 2D ion coincidence technique provides information on the energetics involved in the dissociation of any multiply charged ions formed. In the case of BCI3, further insight on the possible dissociation dynamics of BC132+ is reported. Following the investigations of N2O, BCI3 and SF6, the apparatus was commissioned to produce absolute partial ionization cross-sections and absolute precursor specific partial ionization cross-sections from 30-200 eV. Experimentally, the commissioning involved the addition of a Spinning Rotor Gauge (SRG) and a new gas inlet line to the source region. These investigations have extended the data determined for the electron ionization of N20 and have also enabled the absolute cross-section data for the electron ionization of C2H2 to be determined.
3
O'Neill, Raymond W. "Electron-ion excitation studies." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333828.
Повний текст джерела
4
Lea-Wilson, M. A. "Electron spin resonance studies of electron irradiated diamond." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381911.
Повний текст джерела
5
Thakur, Rashmi. "Studies on corona-charged polypropylene fibrous electrets." Thesis, IIT Delhi, 2015. http://eprint.iitd.ac.in:80//handle/2074/8198.
Повний текст джерела
6
Koch, Katrin. "Crystal structure, electron density and chemical bonding in inorganic compounds studied by the Electric Field Gradient." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-24233.
Повний текст джерелаАнотація:
The goal of solid state physics and chemistry is to gain deeper understanding of the basic principles of condensed matter. This ongoing process is achieved by the combination of experimental methods and theoretical models. One theoretical approach are the so-called first-principles calculations, which are based on the concept of density functional theory (DFT). In order to test the reliability of a band structure calculation, its results have to be compared with experiments. Since the electron density, the main constituent of DFT codes, cannot be directly determined experimentally with sufficient accuracy (e.g., by X-ray diffraction), other experimentally available properties are needed for the comparison with the calculation.
A quantity that can be measured with high accuracy and that provides
indirect information about the electron density is the electric field
gradient (EFG). The EFG reflects local structural symmetry properties of the charge distribution surrounding a nucleus: the EFG is nonzero if the
density deviates from cubic symmetry and therefore generates an
inhomogeneous electric field at the nucleus. Since the EFG is highly
sensitive to structural parameters and to disorder, it is a
valuable tool to extract structural information. Furthermore, the
evaluation of the EFG can provide valuable insight into the chemical
bonding.
Whereas the experimental determination of the quadrupole frequency
and the closely related EFG has been possible for more than 70 years,
reliable values for calculated EFGs could not be obtained before 1985,
when an EFG module was implemented in the full-potential,
linearised-augmented-plane-wave code WIEN. Since the full-potential local-orbital minimum-basis scheme FPLO is numerically very efficient and its local-orbital scheme allows an easy analysis of the different contributions to the EFG, one goal of this work was the implementation of an EFG module within the FPLO code.
The newly implemented EFG module was applied to different systems:
starting from simple metals, then approaching more complex systems and finally tackling strongly correlated oxides. Simultaneously, the EFGs
for the studied compounds were determined experimentally by NMR
spectroscopists. This close collaboration enables the comparison of
the calculated EFGs with the experimental observations, which makes it
possible to extract more physical and chemical information from the
measured values regarding structural relaxation, distortion, the
chemical bond or the relevance of electron correlation.
In the last part of this work, the importance of corrections that go
beyond the EFG are discussed. Such corrections arise for any multipole order of the hyperfine interactions, and are due to electron penetration into the nucleus. A correction similar to the isomer shift, coined here the "quadrupole shift" is examined in detail.
7
Atkins, Danielle S., and N/A. "Electron Coincidence Studies of Molecules." Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070920.112918.
Повний текст джерелаАнотація:
The electron-electron coincidence (e,2e) technique yields complete kinematical information about the electron impact ionization process. The (e,2e) technique has been widely used to study dynamical effects in ionizing collisions with atomic targets, however studies of molecular ionization using this technique have been very limited. Recently further experimental studies of small molecules have been proposed, as the cross sections of small molecules are now computable using sophisticated theoretical approaches [77, 24]. This thesis presents dynamical investigations for the electron impact ionization of the molecular targets H2O and H2, employing the (e,2e) technique to experimentally measure the triple differential cross section (TDCS). The TDCS is defined as the probability that a bound electron will be ejected from the target atom or molecule (into a particular direction with a defined energy) and the initial electron will be scattered into a particular direction with a particular energy. All TDCSs presented within this thesis were performed using an electron coincidence spectrometer in the coplanar asymmetric geometry at intermediate incident electron energies. This thesis presents the electron impact ionization TDCSs of H2O. A series of measurements were performed using H2O in the vapour form. Measurements of the TDCS are presented for the 2a1 atomic-like orbital and the 1b2, 3a1 and 1b1 molecular orbitals at a common incident electron energy of 250eV, ejected electron energy of 10eV and scattering angle of -15o. The experimental TDCSs are compared with theoretical cross sections that were calculated by Champion et al [25, 26] using a distorted wave Born approach (DWBA). TDCS measurements for the single ionization of the hydrogen molecule, H2 were performed as in recent years there has been evidence that indicates the ejected electron angular distribution is perturbed due to Young-type interference effects. The oscillatory structure which is predicted in the cross section is due to the two-centred nature of the molecule [27, 29]. This thesis presents experimental TDCSs for the ionization of H2 which are compared to TDCSs of helium. A series of measurements for the TDCSs of H2 and He are presented at a common incident electron energy of 250eV and scattering angle of -15o, for a range of ejected electron energies between 10eV and 100eV. The experimental TDCSs are compared with two types of theoretical calculations.
8
Atkins, Danielle S. "Electron Coincidence Studies of Molecules." Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367729.
Повний текст джерелаАнотація:
The electron-electron coincidence (e,2e) technique yields complete kinematical information about the electron impact ionization process. The (e,2e) technique has been widely used to study dynamical effects in ionizing collisions with atomic targets, however studies of molecular ionization using this technique have been very limited. Recently further experimental studies of small molecules have been proposed, as the cross sections of small molecules are now computable using sophisticated theoretical approaches [77, 24]. This thesis presents dynamical investigations for the electron impact ionization of the molecular targets H2O and H2, employing the (e,2e) technique to experimentally measure the triple differential cross section (TDCS). The TDCS is defined as the probability that a bound electron will be ejected from the target atom or molecule (into a particular direction with a defined energy) and the initial electron will be scattered into a particular direction with a particular energy. All TDCSs presented within this thesis were performed using an electron coincidence spectrometer in the coplanar asymmetric geometry at intermediate incident electron energies. This thesis presents the electron impact ionization TDCSs of H2O. A series of measurements were performed using H2O in the vapour form. Measurements of the TDCS are presented for the 2a1 atomic-like orbital and the 1b2, 3a1 and 1b1 molecular orbitals at a common incident electron energy of 250eV, ejected electron energy of 10eV and scattering angle of -15o. The experimental TDCSs are compared with theoretical cross sections that were calculated by Champion et al [25, 26] using a distorted wave Born approach (DWBA). TDCS measurements for the single ionization of the hydrogen molecule, H2 were performed as in recent years there has been evidence that indicates the ejected electron angular distribution is perturbed due to Young-type interference effects. The oscillatory structure which is predicted in the cross section is due to the two-centred nature of the molecule [27, 29]. This thesis presents experimental TDCSs for the ionization of H2 which are compared to TDCSs of helium. A series of measurements for the TDCSs of H2 and He are presented at a common incident electron energy of 250eV and scattering angle of -15o, for a range of ejected electron energies between 10eV and 100eV. The experimental TDCSs are compared with two types of theoretical calculations.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Faculty of Science, Environment, Engineering and Technology
Full Text
9
Shaw, Laura Angela. "NMR Studies of DNA Models for Electron Transfer Studies." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521528.
Повний текст джерела
10
Kumar, Santhosh Tekke Athayil, and santhosh kumar@anu edu au. "Experimental Studies of Magnetic Islands, Configurations and Plasma Confinement in the H-1NF Heliac." The Australian National University. Research School of Physical Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20080611.171513.
Повний текст джерелаАнотація:
Rational magnetic flux surfaces in fusion (toroidal plasma confinement) devices can break the magnetic field lines and reconnect
them in the form of magnetic islands. Formation of these magnetic islands can have a serious impact on the plasma confinement properties of the device. Islands can in general degrade the confinement by
mixing up different regions of the plasma. However there has been experimental evidence of confinement improvement by island induced transport barriers, under certain conditions. Even though there are a
large number of theoretical and experimental works on magnetic islands to date, there is clearly a paucity of convincing experimental
understanding on the nature of behaviour of islands in plasma. This thesis reports detailed experimental studies conducted on the H-1NF heliac stellarator, to gain an in-depth understanding of magnetic islands and their influence in plasma confinement.¶
Work reported in this thesis can be mainly divided into three parts: (a) high resolution imaging of vacuum magnetic islands and flux surfaces of H-1NF, (b) accurate computer modeling of H-1NF magnetic
geometry and (c) detailed experiments on magnetic islands in plasma configurations.¶
Electron-beam wire-tomography in the H-1NF has been used for the high resolution mapping of vacuum magnetic flux surfaces and islands. Point-to-point comparison of the mapping results with
computer tracing, in conjunction with an image warping technique, has enabled systematic exploration of magnetic islands and surfaces of interest. A fast mapping technique has been developed, which
significantly reduced the mapping time and made this technique suitable for mapping at higher magnetic fields.¶
Flux surface mapping has been carried out at various magnetic configurations and field strengths. The extreme accuracy of this technique has been exploited to understand the nature of error fields,
by point-by-point matching with computer tracing results. This has helped in developing a best-fit computer model for H-1NF magnetic configurations, which can predict rotational transform correct to
three decimal places. Results from plasma experiments on magnetic configuration studies are best explained by the new model.¶
Experiments with low order magnetic islands in plasma configurations yielded some new results. It has been observed that the low order magnetic islands (m = 2) near the core of the plasma serve as pockets of improved confinement region under favourable conditions. This results in significant profile modifications including enhancement of the radial electric field near the core to a large positive value. The characteristics of islands are found to be
dependent on the plasma collisionality and the island width.¶
Experiments with a magnetic configuration which exhibits no vacuum islands, but the core rotational transform very close to
low order rational value, show a spontaneous transition of the radial electric field near the core to a large positive value (nearly 5
kV/m), with a strong electric field shear (nearly 700 kV/m2) and localised improvement in confinement, during the discharge. Evidence indicates that the transition is driven by the excitation of low order magnetic islands near the axis during the plasma discharge, due to the modification of rotational transform profile by toroidal plasma currents. The situation is similar to the Core Electron-Root Confinement (CERC) observed during high temperature ECH
plasma discharges on other helical devices. This result provides an experimental evidence for the hypothesis that the threshold conditions for observing CERC can be reduced by exciting magnetic islands near
the core of the plasma.
11
van, Emde Boas Evert H. "Linguistic studies in Euripides' Electra." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:dbecc2f8-f980-4a33-9fdc-20d8c1329dc5.
Повний текст джерелаАнотація:
Euripides’ Electra has long been one of the playwright’s most controversial works. This book offers a reading of the play concentrating on its language, which is analysed by applying a variety of modern linguistic approaches: conversation analysis, pragmatic theories of speech acts and inference, politeness theory, the study of the interplay of gender and language, paroemiology, and the study of discourse cohesion. The first three chapters argue for the Peasant, Electra and Orestes, respectively, that their linguistic behaviour constitutes a vital part of their characterisation. The Peasant’s (ch. 1) sturdy morality is established by the way his language becomes more forceful when he touches on ethical questions; it is then tested in his conversations with Electra, where his language is suggestive of a conflict between his morals and his desire to please his royal wife. Electra herself (ch. 2) is characterised initially by the inability to communicate successfully with those around her — a disconnect which is suggestive of the fundamental incongruity of her circumstances. This adds a dimension to her motivations, which, as a force driving Electra’s linguistic behaviour, remain highly stable throughout the play up until the matricide. Another consistent feature of Electra’s language is the way it is patterned by her gender. Orestes’ characterisation in the early part of the play is ingeniously kept to a minimum through his sustained disguise. Various aspects of his language, but particularly his use of gnomai, contribute to that disguise, which involves a suppression of emotion, an avoidance of self-reference, and the exertion of control over the flow and topic of his conversation with Electra. We can only interpret a dramatic text if we know what it says, and if we know who says what. In chapter 4, I argue that the linguistic approaches I adopt can also help us in making a determination about textual-critical problems, particularly concerning the issue of speaker-line attribution (two notorious cases are discussed: 671-84 and 959-87). The final two chapters deal with longer speeches. In the messenger scene (ch. 5), Euripides uses linguistic devices to create an ebb and flow of suspense, and to manipulate audience expectation. In the agon (ch. 6), differences in the way Clytemnestra and Electra structure their speeches, particularly their narrationes, reveal much about their different (and fundamentally irreconcilable) viewpoints and approaches.
12
Chaudhry, M. A. "Electron and X-ray spectroscopy of electron-atom collisions." Thesis, University of Stirling, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379507.
Повний текст джерела
13
Ma, Lianxi. "Electron tunneling studies of Mn12-Acetate." Diss., Texas A&M University, 2008. http://hdl.handle.net/1969.1/85957.
Повний текст джерелаАнотація:
We used self-assembling tunnel junctions (SATJs) to study the electron transport
through films of the molecular magnets, Mn12-Acetate. Pulse laser deposition
(PLD) was used to deposit two monolayers of Mn12-Acetate on thin Pt wires (diameter
0.001 in). The electron tunneling current was measured with typical bias voltages
from -1 to 1 V at liquid helium temperature, 4.2 K. I, dI/dV , and d2I/dV 2 signals
were directly acquired with the aid of a current amplifier and two lock-in-amplifiers.
Results show that the differential conductance is approximately 10â 6 S for bias voltages
0.04 V < or =| V |< or = V and exhibits a strong voltage dependence. In the region
| V |< or = 0.04 V, we find a zero-bias feature (ZBF) in which the differential conductance
is suppressed. In some samples, we observe I -V staircases which we attribute to
electrons "hopping" between the electrodes and the molecules. The observed hysteresis
was attributed to the slow relaxation of molecules re-orienting within the junction.
Abrupt conductance jumps at a bias voltage of -0.12 V were also observed and may
indicate state transitions in the Mn12-Acetate molecules. Furthermore, we observed
that the zero bias feature (ZBF) can switch from an enhancement to a suppression
of the differential conductance.
A dip and dry (DAD) method was also used to form films of Mn12-Acetate on
Al and Pt wires. Although the conductances were similar to those obtained using the PLD method, there were some subtle differences. In particular, we did not observe
the I -V staircases and the state jumps were more ambiguous. The differential
conductance for the Mn12-Acetate films on Al wires were typically 10- 7 S, which we
attributed to the oxide layer on Al surfaces.
We have also found substantial changes in the I - V characteristics when the
Pt wires coated with the Mn12-Acetate films were stored in 10-2 Torr for 6 months.
In particular, we observed many new features such as peaks in the conductance as a
function as the bias voltage. We believe that these effects may be caused by the slow
oxidation of the Mn12-Acetate molecules.
14
Guo, Liang-Hong. "Electrochemical studies of biological electron transfer." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258256.
Повний текст джерела
15
Hyslop, Michael. "Electron diffraction studies of unsupported clusters." Thesis, University of Canterbury. Physics and Astronomy, 2002. http://hdl.handle.net/10092/5563.
Повний текст джерелаАнотація:
The motivation to study the structure of clusters is the possible observation of unusual structures for small cluster sizes. The presence of such structural size effects is generally associated with the optimization of surface energy in clusters. For metals that have face centred cubic (FCC) structure in the bulk, optimization of the surface energy typically results in icosahedral or decahedral structures being preferred for nanometre sized clusters.
The inert gas aggregation (IGA) technique has been used to produce a beam of clusters (diameter ≤10 nm) for structural studies using electron diffraction. Studying the clusters while in a molecular beam, as opposed to on a substrate, means that the clusters are unsupported and thus free of any perturbing effects due to a substrate. The use of a beam also means each cluster is subjected to only a brief exposure to the electron beam, minimizing effects due to the electron beam. Attempts to obtain diffraction patterns from Zn clusters were unsuccessful, however using Pb it was possible to obtain diffraction patterns from clusters using a wide range of parameters in the IGA source.
The experimental diffraction patterns result from the range of different sized and structured clusters produced by the source. The analysis reflects the distribution of cluster sizes and structures by combining diffraction patterns from model clusters with a range of sizes and structures to produce a best fit to the experimental pattern. In general, two sets of model clusters are used: the first set contains models with up to ~6500 atoms, created using bulk and symmetry properties for clusters with FCC, decahedral and icosahedral structure. The second set contains the same sizes and structures as the first, however each model has been relaxed using molecular dynamics (MD) simulations. In the analysis of several experimental diffraction patterns, models with twinned FCC, liquid, anti-Mackay icosahedral and shaved icosahedral structures are also considered. Domain size estimates are obtained using the fit results; cluster size estimates are made from samples collected from the beam and observed in a TEM. Size estimates are also made using the Scherrer formula and the Fourier inversion method .
Analysis of diffraction patterns from Pb clusters shows that changing the type of inert gas produces the greatest variation in the size and structure of the clusters. The small clusters produced using He are found to be based on icosahedral structures. The clusters produced using Ar are larger than those produced using He and the diffraction patterns are difficult to interpret. The patterns bear a strong resemblance to those from decahedra, but diffraction patterns from decahedra are similar to those from twinned FCC structures, and from a combination of shaved icosahedra and FCC structures. FCC structure is not observed, which is both interesting and surprising.
16
Duckett, Gordon Richard. "Electron microscope studies of organic pigments." Thesis, University of Glasgow, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305588.
Повний текст джерела
17
Ward, N. P. "Electron-optical studies of biological macromolecules." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383898.
Повний текст джерела
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Grosche, Freidrich Malte. "Pressure studies on correlated electron systems." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387721.
Повний текст джерела
19
Loh, Yen Lee. "Studies of strongly correlated electron systems." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615109.
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20
Scherliess, Ludger. "Empirical Studies of Ionospheric Electric Fields." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/6823.
Повний текст джерелаАнотація:
The first comprehensive study of equatorial- to mid-latitude ionospheric electric fields (plasma drifts) is presented, using extensive incoherent scatter radar measurements from Jicamarca, Arecibo, and Millstone Hill, and F-region ion drift meter data from the polar orbiting DE-2 satellite. Seasonal and solar cycle dependent empirical quiet-time electric field models from equatorial to mid latitudes are developed, which improve and extend existing climatological models. The signatures of electric field perturbations during geomagnetically disturbed periods, associated with changes in the high-latitude currents and the characteristics of storm-time dynamo electric fields driven by enhanced energy deposition into the high-latitude ionosphere, are studied. Analytical empirical models that describe these perturbation drifts are presented.
The study provided conclusive evidence for the two basic components of ionospheric disturbance electric fields. It is shown that magnetospheric dynamo electric fields can penetrate with significant amplitudes into the equatorial- to mid-latitude ionosphere, but only for periods up to 1 hour, consistent with results from the Rice Convection Model. The storm-time wind-driven electric fields are proportional to the high-latitude energy input, vary with local time and latitude, and have largest magnitudes during nighttime. These perturbations affect differently the zonal and meridional electric field components. It is shown that equatorial zonal electric fields (vertical drifts) can be disturbed up to 30 hours after large enhancements in the high-latitude currents. These perturbation electric fields are associated with enhanced high-latitude energy deposition taking place predominantly between about 1-12 hours earlier and found to be in good agreement with the Blanc-Richmond disturbance dynamo model. A second class of perturbations occurs around midnight and in the dawn-noon sector with delays of about 18-30 hours between the equatorial- and the high-latitude disturbances , and maximizes during locally quiet geomagnetic times.
The latitudinal variation of the meridional disturbance electric fields (zonal drifts) is also presented. It is shown that these perturbation electric fields are predominantly downward/equatorward at all latitudes and due to both prompt penetration and disturbance dynamo electric fields. These results are also generally consistent with predictions from global convection and disturbance dynamo models.
21
Mäkinen, A. (Ari ). "Experimental spectroscopic studies of metals with electron, ion, and optical techniques." Doctoral thesis, University of Oulu, 2014. http://urn.fi/urn:isbn:9789526203149.
Повний текст джерелаАнотація:
Abstract
In this thesis, different spectroscopic methods are used for studying metals. Electron spectroscopy is applied for the study of binding energy shifts between atomic vapor and solid metals. Photoionization and Auger decay of high temperature aluminum vapors are investigated. Ionization of atomic chromium metal vapor by light absorption is studied with synchrotron radiation and time-of-flight ion mass spectroscopy. Optical spectroscopy is used for studying light emission from electric arc furnace plasma in experimental apparatuses developed during this work. Experimental techniques and sample preparation methods are presented.
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Mäkinen, A. (Ari). "Experimental spectroscopic studies of metals with electron, ion, and optical techniques." Doctoral thesis, University of Oulu, 2014. http://urn.fi/urn:isbn:9789526203140.
Повний текст джерелаАнотація:
Abstract In this thesis, different spectroscopic methods are used for studying metals. Electron spectroscopy is applied for the study of binding energy shifts between atomic vapor and solid metals. Photoionization and Auger decay of high temperature aluminum vapors are investigated. Ionization of atomic chromium metal vapor by light absorption is studied with synchrotron radiation and time-of-flight ion mass spectroscopy. Optical spectroscopy is used for studying light emission from electric arc furnace plasma in experimental apparatuses developed during this work. Experimental techniques and sample preparation methods are presentedOriginal papers The original publications are not included in the electronic version of the dissertation. Huttula, M., Jänkälä, K., Mäkinen, A., Aksela, H., & Aksela, S. (2008). Core shell electron spectroscopy on high temperature vapors: 2s photoionization and Auger decay of atomic aluminium. New Journal of Physics, 10(1), 13009. https://doi.org/10.1088/1367-2630/10/1/013009 Huttula, M., Partanen, L., Mäkinen, A., Kantia, T., Aksela, H., & Aksela, S. (2009). KLL Auger decay in free aluminum atoms. Physical Review A, 79(2). https://doi.org/10.1103/physreva.79.023412 Aksela, S., Kantia, T., Patanen, M., Mäkinen, A., Urpelainen, S., & Aksela, H. (2012). Accurate free atom–solid binding energy shifts for Au and Ag. Journal of Electron Spectroscopy and Related Phenomena, 185(8–9), 273–277. https://doi.org/10.1016/j.elspec.2012.05.007 Mäkinen, A., Patanen, M., Aksela, S., & Aksela, H. (2012). Atom-solid 3p level binding energy shift of transition metals Cr, Mn, Fe, Co, and Ni. Journal of Electron Spectroscopy and Related Phenomena, 185(12), 573–577. https://doi.org/10.1016/j.elspec.2012.12.006 Mäkinen, A., Niskanen, J., & Aksela, H. (2012). Relative photoionization cross section of Cr atoms in the valence region. Physical Review A, 85(5). https://doi.org/10.1103/physreva.85.053411 Mäkinen, A., Niskanen, J., Tikkala, H., & Aksela, H. (2013). Optical emission from a small scale model electric arc furnace in 250–600 nm region. Review of Scientific Instruments, 84(4), 43111. https://doi.org/10.1063/1.4802833
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Bruin, Jan Adrianus Nathan. "Transport studies of the itinerant metamagnet Sr₃Ru₂O₇ near its quantum critical point." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3656.
Повний текст джерелаАнотація:
Strongly correlated metals are known to give rise to a variety of exotic states. In particular, if a system is tuned towards a quantum critical point, new ordered phases may arise. Sr₃Ru₂O₇ is a quasi-two dimensional metal in which field-tuned quantum criticality has been observed. In very pure single crystals of this material, a phase with unusual transport properties forms in the vicinity of its quantum critical point. Upon the application of a small in-plane field, electrical resistivity becomes anisotropic, a phenomenon which has led to the naming of this phase as an `electron nematic'. The subject of this thesis is a study of the electrical transport in high purity crystals of Sr₃Ru₂O₇. We modified an adiabatic demagnetisation refrigerator to create the conditions by which the entire temperature-field phase diagram can be explored. In particular, this allowed us to access the crossover between the low-temperature Fermi liquid and the quantum critical region. We also installed a triple axis `vector magnet' with which the applied magnetic field vector can be continuously rotated within the anisotropic phase. We conclude that the low- and high-field Fermi liquid properties have a complex dependence on magnetic field and temperature, but that a simple multiple band model can account for some of these effects, and reconcile the measured specific heat, dHvA quasiparticle masses and transport co-efficients. At high temperatures, we observe similarities between the apparent resistive scattering rate at critical tuning and those observed in other quantum critical systems and in elemental metals. Finally, the anisotropic phase measurements confirm previous reports and demonstrate behaviour consistent with an Ising-nematic, with the anisotropy aligned along either of the principal crystal axes. Our observations are consistent with the presence of a large number of domains within the anisotropic phase, and conclude that scattering from domain walls is likely to contribute strongly to the large measured anisotropy.
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Gee, Philip James. "Studies of electron-electron interactions in a system of reduced dimensionality." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360300.
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He, Qizhi Chan Sunney I. Chan Sunney I. "Cytochrome c oxidase : studies of electron input and intramolecular electron transfer /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-10052007-085601.
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Halls, Daniel Charles. "Remote Electron Beam Induced Current (REBIC) and cathodoluminescence studies of some zinc oxide and varistor ceramics." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8008.
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Pach, Elzbieta. "Electron microscopy studies on functional carbon nanotubes." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/456581.
Повний текст джерелаАнотація:
La presente tesis doctoral se centra en el estudio exhaustivo de nanotubos de carbono funcionales por medio de técnicas de microscopía electrónica. Los nanotubos de carbono (CNTs) funcionales están atrayendo una creciente atención debido a su potencial uso para aplicaciones biomédicas, incluyendo para la adquisición de imágenes in vivo, acumulación selectiva en tumores y sistemas de administración de fármacos. Una ventaja intrínseca de los nanotubos de carbono es que su cavidad interna puede llenarse con una carga útil de interés mientras que la superficie externa puede modificarse para mejorar su dispersabilidad y biocompatibilidad.
Debido a su potencial aplicación en el campo biomédico, es esencial una caracterización detallada de las muestras en todas las etapas de su proceso de preparación (purificación, acortamiento, llenado y funcionalidad externa). Para lograr este objetivo, en esta tesis doctoral hemos empleado tanto los análisis ya establecidos que incluye microscopía electrónica de transmisión de alta resolución para estudiar la estructura del material de relleno o espectroscopia de dispersión de energía de rayos X para evaluar su composición, pero también hemos explorado el uso de otras técnicas para ampliar las posibilidades de caracterización de las muestras.
En este sentido, hemos optimizado las condiciones para el estudio de las longitudes de CNTs monocapa purificados por microscopía electrónica de barrido de alta resolución (HRSEM) con sensibilidad superficial. Además, la microscopía electrónica de transmisión y barrido (STEM) a bajos voltajes se ha demostrado como una técnica eficiente y rápida para evaluar el rendimiento del rellenado y la pureza del material. De hecho, la combinación de alta resolución espacial y el trabajo a bajos voltajes de esta técnica la ha hecho particularmente adecuada para el estudio de la interacción de nanotubos de carbono funcionales con muestras biológicas, como por ejemplo células.
Algunos de los compuestos con interés para aplicaciones biomédicas empleados en este trabajo tienen una estructura laminar. Se sabe que los materiales laminares forman monocapas que pueden tener propiedades mejoradas o nuevas debido a efectos de confinamiento. Los CNT pueden actuar como plantillas para guiar los materiales laminares a formar nanotubos monocapa. Este es el caso de los haluros de lutecio y el yoduro de plomo. En esta tesis de doctorado hemos conseguido la formación de nanotubos de haluros de lutecio de tamaño subnanométrico, y su naturaleza tubular se ha demostrado mediante STEM con corrector de aberraciones y simulaciones de imagen. Además, se ha logrado el crecimiento con alto rendimiento de nanotubos de PbI2 en el exterior de CNTs. La estructura de los híbridos se ha revelado mediante STEM con aberración corregida y tomografía electrónica. Cabe destacar que las propiedades ópticas de los híbridos difieren de las del PbI2 en masa. El desplazamiento azul observado por fotoluminiscencia se ha confirmado mediante análisis en híbridos PbI2-CNT individuales por catodoluminiscencia-STEM.
En conclusión, durante este proyecto de doctorado la gama de técnicas de microscopía electrónica utilizadas para el estudio de CNT funcionales se ha ampliado para obtener una caracterización exhaustiva de las muestras.The present PhD thesis focuses on the thorough study of functional carbon nanotubes by means of electron microscopy techniques. Functional carbon nanotubes (CNTs) are attracting an increased attention due to their potential use for biomedical applications, including in vivo imaging, tumour targeting and drug delivery systems. An intrinsic advantage of carbon nanotubes is that their inner cavity can be filled with a chosen payload whilst the outer surface can be modified to improve their dispersability and biocompatibility. Being the envisaged application in the biomedical field, a detailed characterization of the samples in all the steps of the preparation process (namely purification, shortening, filling and external functionalization) is mandatory. To achieve this goal, in this PhD thesis we have employed already established analysis including high resolution transmission electron microscopy to study the structure of the filling material, or energy dispersive X-ray spectroscopy to assess their composition, but also we have explored the use of other techniques to expand the possibilities of characterization of the samples. In this sense, we have optimized the conditions for the study of the lengths of as-purified single-walled CNTs by surface sensitive high resolution scanning electron microscopy (HRSEM). Besides, low voltage scanning transmission electron microscopy (STEM) has been demonstrated as a time-efficient technique for assessment of filling yield and purity. Indeed, the combination of high spatial resolution and low voltage operation of this technique has made it particularly suitable for the study of the interaction of functional carbon nanotubes with biological samples such as cells. Some of the employed compounds with interest for biomedical applications have a layered structure in their bulk form. Layered materials are known to form monolayers which may exert enhanced or novel properties due to the confinement effects. CNTs may act as templates to guide those layered materials to form single-layered nanotubes. This is the case of lutetium halides and lead iodide. In this PhD thesis we have succeeded in the formation of lutetium halide subnanometer-sized nanotubes, and proved their tubular nature by aberration corrected STEM and image simulations. Additionally, the high yield growth of PbI2 nanotubes on the exterior of CNTs has been achieved. Thanks to aberration corrected HAADF STEM and electron tomography, the structure of the hybrids has been revealed. Remarkably, the optical properties of the hybrids differ from those of the bulk PbI2. The blue shift observed by photoluminescence has been further confirmed by cathodoluminescence STEM analysis detected on individual PbI2-CNT hybrids. In conclusion, during this PhD project the range of electron microscopy techniques used for the study of functional CNTs has been expanded to get a thorough characterisation of the samples.
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Helme, Lucy. "Neutron Scattering Studies of Correlated Electron Systems." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491531.
Повний текст джерелаАнотація:
This thesis presents neutron scattering studies of three correlated electron systems, each of which exhibit different competing interactions. These include charge order, magnetic order and lattice degrees of freedom. The main focus is on magnetic excitations within the systems. In all cases the experimental data have been analysed through comparison with theoretical models. Chapter 3 presents an investigation into the Jahn-Teller effect in the rare earth oxide Pr02, through inelastic neutron scattering studies of the crystal field transitions above and below a static structural distortion temperature. The data are compared with a point-charge model of the crystal field levels. \Ve conclude that the observed temperature evolution of the crystal field levels originates from the structural distortion due to the Jahn-Teller effect. Chapter 4 describes studies of magnetic excitations in the layered charge-ordered transition-metal oxide La1.5Sro.5Co04 through inelastic neutron scattering studies, and subsequent comparison with spin-wave dispersion models. It was found that the spin-wave excitations were decoupled from the charge order. Inclusion of the strong crystal anisotropy was necessary in order to successfully describe the data. Chapters 5 and 6 present studies of the magnetically ordered phase of Nax Co02 with x rv 0.75, a metallic layered transition-metal oxide. Chapter 5 describes investigations into the magnetic excitations in the compound, which were successfully modelled by linear spin-wave theory, including terms for the anisotropy. The excitations were found to be highly three dimensional despite the layered nature of the crystal structure. Chapter 6 presents a diffraction study of a spin-flop transition in an applied magnetic field, which confirmed the magnetic order. The transition field was found to be in excellent agreement with the exchange and anisotropy parameters extracted in chapter 5.
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Greenley, Katherine R. "Electron spin resonance studies of food systems." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/843041/.
Повний текст джерелаАнотація:
ESR has been used to study multi-phase food systems, including ice cream and chocolate, using both spin probes and spin labels. Chemical and physical methodologies were developed and applied to study the behaviour of 1,1,3,3-tetramethylisoindolin-2-yloxyl (TMIO), the 5-pentyl derivative (PTMIO) and the water-soluble 5-sulphonate (NaTMIOS) spin probes in hydrophilic and hydrophobic phases over a range of temperatures. Linewidths and hyperfine coupling constants (aN) were derived using fitting and simulating computer software, from which rotational correlation times (tauc) and enthalpies of activation of molecular rotation were calculated. These give an indication of the local environment of the probe. In the hydrophilic phase of ice cream there was a sharp reduction in probe mobility at -18°C, which did not occur in the hydrophobic phase. In chocolate, an essentially hydrophobic system, no sudden changes in mobility were detected although at around 60°C there was a change in the enthalpy of activation. Spectral deconvolution techniques enabled the simultaneous study of NaTMIOS and TMIO in the hydrophilic and hydrophobic phases of ice cream and enabled the study of TMIO spectra in the presence of the underlying spectrum of the radical present in chocolate. Guar gum and xanthan gum are used as stabilisers in ice cream and were spin-labelled using 5-carboxy-TMIO (CTMIO) and 5-amino-TEMPO respectively. The ESR spectra showed that the mobilities of the nitroxide moieties were comparable with the free spin probes. The addition of the gums to a sucrose solution, a model hydrophilic system, had no appreciable effect on the mobility of the NaTMIOS spin probe.
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Kaufmann, Martin. "Electron Diffraction Studies of Unsupported Antimony Clusters." Thesis, University of Canterbury. Physics and Astronomy, 2006. http://hdl.handle.net/10092/1269.
Повний текст джерелаАнотація:
This thesis contains two main parts: the first part focusses on an electron diffraction study on unsupported antimony (Sb) clusters, while in the second part the design and development of a time-of-flight mass spectrometer (TOFMS) is discussed. Electron diffraction is an ideal tool to study the structure of clusters entrained in a beam. The main advantage of this technique is the ability to study the clusters in situ and in an interaction-free environment. It is therefore not necessary to remove the particles from the vacuum system which would lead to oxidation. Since the particles do not have to be deposited on a sample for further investigation, there is also no substrate which could influence the cluster structure. An additional advantage is the short exposure to the electron beam, thereby minimising the likelihood of damaging the particles. Sb clusters were produced using an inert-gas aggregation source. To control the cluster properties the source temperature, pressure and type of cooling gas can be adjusted. In the range of source parameters tested, Sb clusters with three different structures were observed: a crystalline structure corresponding to the rhombohedral structure of bulk Sb, an amorphous structure equivalent to the structure of amorphous Sb thin films, and a structure with the same diffraction signature as Sb4 (Sb evaporates mainly as Sb4). This last structure was found to belong to large particles consisting of randomly oriented Sb4 units. In order to study the size distributions and morphologies of the Sb clusters, the clusters were deposited onto substrates and studied under an electron microscope. The crystalline particles showed a wide variety of strongly faceted shapes. Depending on source conditions, the average cluster diameters ranged from 15 to 130 nm. There was a considerable disagreement between these values and the size estimates from the diffraction results with the latter being smaller by an order of magnitude. This might be due to the existence of domains inside the clusters. The amorphous particles were all found to be spherical with mean sizes between 27 and 45 nm. The Sb4 particles showed a liquid-like morphology and tended to coalesce easily. Their sizes ranged from 18 to 35 nm. To obtain an independent method for determining the cluster size, a TOFMS was designed and developed in collaboration with Dr Bernhard Kaiser. However, the TOFMS failed to detect a cluster signal in the original set-up which is most likely due to a defective ioniser and underestimated cluster energies. Further tests were performed in a new vacuum system and mass spectra for palladium clusters were successfully recorded.
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Zhang, Bo. "Ferritin : mechanistic studies and electron transfer properties /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1533.pdf.
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Koda, Nobuko. "Transmission electron microscopy studies of fega alloys." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/167.
Повний текст джерелаАнотація:
Thesis (M.S.) -- University of Maryland, College Park, 2003.Thesis research directed by: Dept. of Material, Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Erol, Mustafa. "Phonon studies in two dimensional electron gases." Thesis, Lancaster University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317611.
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Grant, A. I. "Electron spin resonance studies of transient species." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354833.
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Lyster, Martin. "Electron microscope studies of cadmium mercury telluride." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238271.
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Yu, Chak Chung Andrew. "Electron microscopy studies of magnetic tunnel junctions." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302402.
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Christensen, K. N. "Electron microscope studies of oxygen implanted silicon." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292615.
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Wurl, Andreas. "Electron diffraction studies of unsupported bismuth clusters." Thesis, University of Canterbury. Physics and Astronomy, 2003. http://hdl.handle.net/10092/5581.
Повний текст джерелаАнотація:
This study uses electron diffraction to investigate the structure of clusters, which are small particles containing between 3 and 105 atoms. Because of their size clusters represent the link between molecules and bulk material. Of particular interest is the appearance of structures that are forbidden in the bulk as the particle size decreases. One of the main reasons why structural changes occur is the increased proportion of surface atoms in small clusters which may lead to a rearrangement of the atoms in a cluster due to the need to minimise surface as well as bulk energies.
Electron diffraction applied to cluster beams allows the study of the structure of small particles, free of contamination and without interaction with a substrate. The exposure time of the clusters in the beam is very short limiting the possibility of altering the clusters by the electron beam. The high intensity cluster beam necessary for this diffraction experiment is generated by an inert-gas aggregation source.
The two main parts of this thesis work are the development of a new detector system to record electron diffraction patterns and the study of the structure of unsupported Bi clusters. Furthermore, two new analysis tools based on existing techniques have been developed and implemented.
The new detector system uses a pair of linear diode arrays to measure the radial intensity profile of the Debye-Scherrer ring diffraction pattern. The scattered electrons are detected through secondary charge created on impact in the semiconductor material of the sensor pixels. The detector operates differently compared to its predecessor enhancing the quality of the diffraction patterns.
The diffraction patterns from Bi particles can be categorised into patterns from crystalline clusters and patterns with liquid/amorphous features. In the case of the crystalline particles, the diffraction patterns indicate a rhombohedral structure. It has been found that the size estimates determined from the diffraction patterns are smaller than the estimates calculated from TEM images of deposited clusters. This suggests that the particles consist of domains that are separated by lattice defects. The mean sizes of the crystalline particles range from 109 to 231 Å. In the case of liquid/amorphous particles, the patterns have been compared to patterns of liquid drops calculated from structure data of liquid Bi. Although the features in the patterns are similar, the peak positions and relative intensities are different suggesting a new, probably amorphous structure.
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Struthers, H. "Theoretical studies of electron molecule collision processes." Thesis, University of Canterbury. Chemistry, 1998. http://hdl.handle.net/10092/7816.
Повний текст джерелаАнотація:
Theoretical studies of electron-atom and electron-molecule scattering are reported. Second Born scattering amplitudes for the scattering of electrons from helium have been calculated, with the matrix elements of the two particle Green's function being estimated using the closure approximation. Electron-molecular hydrogen amplitudes have also been calculated using a numerical quadrature scheme.
A multichannel method of applying Schwinger's variational theory, which utilises the closure approximation to estimate the second Born like terms required, is introduced and a discussion of possible future work in this area is given.
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Pilling, Robert James. "Synthetic studies towards novel electron transport inhibitors." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262956.
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Saubi, Benjamin Haubiih. "Studies in ferromagnetism using electron polarization analysis." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249391.
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Williams, Tara N. "Reactivity studies of electron poor titanium amides." Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/6909/.
Повний текст джерелаАнотація:
Chapter One presents an overview of olefin polymerisation, which provides the context for the majority of the work described in later chapters. Both Ziegler-Natta and late transition metal systems are described. Chapter Two describes the synthesis and reactivity of trisamido titanium complexes with the diarylamido fragments derived from diphenylamine and di-p-tolylamine. These complexes have been thoroughly studied using NMR spectroscopy. This chapter also presents the syntheses of two rare examples of trisamido methyl complexes. In addition, an improved synthetic route to the cocatalyst, KB(C6F5)4 and the structures of [B(C6F5)3·C4H8O] and [Mg(C6F5)2(Et2O)(dioxane)] are described. Chapter Three describes the polymerisation activity of the catalysts derived from (R2N)3TiCl, (R2N)3TiMe, and [(R2N)3Ti]+ with the cocatalysts MAO, B(C6F5)3, and KB(C6F5)4. Data was recorded for each of the catalysts, and the consumption of propene over time was plotted. Rate constants were found for each of the polymerisation reactions. The mechanism for the polymerisation of each of these was also examined. Chapter Four presents the synthesis and reactivities of new trisamido complexes using 10,11-dihydro-dibenz(b,f )azepinyl, hereafter abbrievated as dda, as the amide fragment. Specifically, syntheses of (dda)3TiCl, (dda)3TiMe and (dda)3TiBH4 are described and their characterisation by NMR spectroscopy and X-ray crystallography is presented. The use of these complexes in synthetic approaches to (dda)3TiH are described. Initial steps in the characterisation of hydride transfer to CO2 from (dda)3TiH are also presented. Chapter Five presents details for the experimental work and Appendices are included, containing selected experimental data.
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Penman, Charles. "Theoretical studies of the free-electron laser." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47218.
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Pugh, Emma. "Pressure studies on strongly interacting electron systems." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621542.
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Cumberlidge, Anne-Marie. "Hydrostatic pressure studies of correlated electron systems." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613379.
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Zhai, Dawei. "Studies on Electron Dynamics in Deformed Graphene." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1540985604827894.
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Snelgrove, Darren William. "Kinetic and mechanistic studies on some one-electron and two-electron reactions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0017/NQ57626.pdf.
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Snelgrove, Darren William Carleton University Dissertation Chemistry. "Kinetic and mechanistic studies on some one-electron and two-electron reactions." Ottawa, 2000.
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49
Barker, Paul D. "Some bioelectrochemical studies." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236246.
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Bailey, Phillip. "Magnetic resonance studies of electro-rheological fluids." Thesis, Royal Holloway, University of London, 1989. http://repository.royalholloway.ac.uk/items/8a94b0c6-b9ba-45c5-a207-98d8a7552bee/1/.
Повний текст джерелаАнотація:
Electro-rheological (ER) fluids, which are dispersions of solid particles in a non-conducting oil, have been studied for the first time at a molecular level using magnetic resonance spectroscopic techniques. The group of fluids on which measurements were first made was the already widely used lithium polymethacrylate dispersed in 20 cs silicone oil. The problems associated with this fluid such as high conductivity, relatively low viscosity changes, and settling out of the solid particles, led to fluids containing zeolites also to be investigated. Mechanical tests were performed on all these fluidsincluding static yield stresses measured at zero shear rate,and then a new electroviscometer was designed and built totest fluid performances in the shear rate range from 1.5 to 43.8 s and temperatures from +5 to +60 C.NMR relaxation measurements were used to study themobilities of the water and the ions in all these solids toinvestigate the relationship between these properties, and the performance of a solid as a constituent in an ER fluid. This is the first time that many of these systems have been studied in this way. ESR was used to study the motion of spin probe radicals in partially hydrated zeolites for the first time. The effect of an electric field on the motion of the spin probe inside a zeolite particle was measured and decreased motion was observed as the strength of the electric field wasincreased in those zeolites which showed a significant EReffect, while no effect on the probe motion was seen for those zeolites which constituted a weak ER fluid. The first saturation transfer ESR experiments have been performed on spin probes inside partially hydrated zeolites that previously had been out of the motional range of conventional CWESR, and the anisotropy of the probe motion has been highlighted.