<p>The system studied in the thesis is a particle in a two-dimensional box on the surface of a sphere with constant radius. The different systems have different radii while the box dimension is kept the same, so the curvature of the surface of the box is different for the different systems. In a system with a sphere of a large radius the surface of the box is almost flat. What happens if the radius is decreased and the symmetry is broken? Will the system become chaotic if the radius is small enough? There are some properties of the eigenfunctions, that show different things depending on whether the system is chaotic or regular. The  amplitude distribution of the probability density, the amplitude distribution of the eigenfunction and the probability density look different for chaotic and regular systems. The main subject of this thesis is to study these distributions.</p>

<p>Utgångspunkten i detta arbete är vårt intresse för hur elever uppnår förståelse i fysik och om/hur de ser kopplingar till verkligheten/vardagen. Anser gymnasieelever att det är viktigt med denna koppling? I vårt arbete har vi valt att dela in fysikundervisningen i fyra moment, genomgång, problemlösning, demonstration samt laboration, här har vi skrivit momenten i ordningen, från det mest abstrakta till det mest konkreta. Vårt syfte är att redogöra för de fyra momentens betydelse i undervisningen när det gäller att alla elever ska kunna uppnå förståelse. Vi har valt att utforma en elevenkät med ett antal frågor kring fysikundervisning och bl.a. frågat vilket moment som i första hand ger en elev förståelse samt om det är någon speciell ordning som eleverna föredrar. Dessutom har ett antal elever intervjuats kring dessa frågor. Fysikelever från tre gymnasieskolor i Växjö kommun, två kommunala och en friskola har svarat på enkäten. Resultatet från enkäten blev att de fyra momenten värderades lika viktiga för förståelsen.</p>

This thesis presents experimental results from the synchrotron cooler and storage ring CRYRING on charge transfer processes in fast electron transfer collisions using high-resolution cold target recoil-ion momentum spectroscopy. The main focus of these studies was to investigate a key concept of quantum mechanics: the wave-particle duality. One series of experiments has been dedicated to the study of heavy particle de Broglie wave interference due to scattering on a molecular ’double slit’. This is a fundamental manifestation of the wave properties of matter. Quantum interference oscillations were observed in the target orientation dependent cross section of single- and double-electron capture from H2 to 1.3 MeV protons and to 1.2 and 2.0 MeV He2+ ions. Another study, included in this work, is a series of angular differential cross section measurements for single-electron capture to 1.3-12.5 MeV kinetic energy protons from He that enabled us to systematically investigate the classically allowed non-radiative electron capture process in fast collisions predicted by L. H. Thomas in 1927. The cross section for this process is expected to have a nonrelativistic, asymptotic dependence on the projectile velocity, vp, of vp−11. This prediction (from 1927) was verified experimentally for the first time through the present measurements. Using the above mentioned experimental data in addition to measurements of double electron capture by 6.0 MeV He2+ from He, we have also studied the dominating, central part of the angular differential cross section, dσ/dΩ, where the peak shapes and widths surprisingly are very similar regardless of projectile energy and the number of captured electrons. We explain this with a diffraction model for the electron capture and calculate the corresponding diffracting electron capture ‘apertures’ from the shapes and widths of the measured cross sections and the projectile de Broglie wavelengths. We have on one hand established very strong experimental support for the picture suggested by Thomas in 1927 in which electrons and protons are described as classical particles. On the other hand, the diffraction picture describes the shapes of the central peaks in dσ/dΩ quite well, and nicely explains appearances of second and a third maxima in the angular differential cross section. It is hard to see how these seemingly contradicting results can be explained through complementary classical and quantum descriptions of the same underlying physical processes. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

The topic of this thesis is redox reactions in two technologically important contexts: firstly, in Li-ion battery electrodes during cycling, and secondly, in copper corrosion in oxygen-free ground water containing sulfide. In an attempt to expand the understanding of the charge uptake process in battery electrodes and the chemical reactions on copper surfaces upon sulfide exposure, soft X-ray spectroscopy has been used to study the electronic structure of these systems. To ascertain the changes in electron density at different atomic sites in a battery electrode material, both X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) have been applied to different electrode materials. This thesis explains in detail the assembling procedure, cycling, and situ sample preparation of the battery materials. Furthermore, two different designs used in in situ experiments for study of batteries during cycling are also discussed. The main result from the Li-ion battery materials is the justification to abandon the view of valences as integers. This is true for all battery electrodes examined in this thesis. Generally, oxygen plays a more important role in the charge uptake than commonly assumed, but also the transition metals and other species apart from expected behavior. In LiMnPO4, even the notion of Li as strictly Li+ must be questioned. Copper is intended to act as a corrosion barrier in a nuclear waste repository. In the corrosion experiments presented in this thesis, different copper oxides were exposed to the conditions present at the planned repository site, with exception for the concentration of sulfide, which was greatly increased. The conclusion from these experiments is that sulfide effectively reduces Cu(II) oxide to Cu(I) compounds and possibly forms a compound containing both oxygen and sulfur. Also, the thickness and inhomogeneity of the copper oxide surface layers are of great importance for the corrosion mechanisms, including passivation.

Radioactive waste management is one of the key issues in sustainability of nuclear energy production. Geological repositories represent today the most appropriate solution to long-term management of high-level radioactive waste. Strategies such as Partitioning and Transmutation of spent nuclear fuel may offer a positive impact on geological repositories, by reducing the mass of transuranium elements to be disposed and the time scale for their radiotoxicity. In this scenario, Accelerator Driven Systems (ADS) may play a relevant role as dedicated burners towards sustainable nuclear energy. The NEXT project at Uppsala University contributes to a European effort to improve nuclear data knowledge for transmutation, providing the first experimental neutron induced data in the 100 to 200 MeV energy region. This thesis presents measurements of double-differential cross sections for production of light-ions in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi. Results are compared with model calculations obtained with state-of-the-art nuclear reaction codes; TALYS-1.2, a modified version of JQMD, and MCNP6. Special focus in this work is given to pre-equilibrium emission of composite light-ions. A new energy dependence in the mechanisms described by the Kalbach systematics used in TALYS to account for composite particle emission in the pre-equilibrium stage is proposed. Data show also the need to include multiple pre-equilibrium emission of composite particles, a mechanism now included in TALYS only for protons and neutrons. The JQMD code was recently modified to include a surface coalescence model in the quantum molecular dynamics description of the formation of composite particles. Comparisons of the measured data with results from this modified JQMD code confirm the importance of coalescence mechanisms for the description of the emission spectra of composite particles. Finally, the neutron-induced data are compared with MCNP6 calculations, to contribute to the process of validation and verification of the code.

This dissertation presents new work and results in the flow of complex fluids and experimental methodologies for their investigation. Plate-like colloidal particles of kaolinite and nickel hydroxide are studied. A study of lamellar fragments and their mixture with the nickel hydroxide particles is also presented. The lamellar fragments are self-assembled structures of surfactant molecules that approximate disks. Particles are seen to align with their large faces parallel to the flow direction under shear and elongational strains. Order parameters have been calculated to quantify the extent of preferential alignment and direction of orientation. The experimental data are supported by comparisons with finite-element fluid mechanics calculations that provide estimates of the flow patterns and the strain rates. Elongational strain rates in the range of 5 − 20 s−1 are required to induce a high degree of alignment with the various sizes of the particles whereas about two to three order of magnitude higher shear strain rates are required. The combination of both elongational and shear strain is an effective means to provide a uniform alignment. Comparison of the Peclet numbers calculated for both the shear and elongational flow are presented and this explains that alignment occurs when the energy per particle of the strain is larger than the thermal energy. Mixtures have shown complex behavior: significant changes in the structure are observed that are not seen to the same extent in samples at rest. X-ray diffraction and small-angle neutron scattering techniques are used to characterize the samples and determine the structure in flowing systems. Laboratory X-ray diffraction can be used to characterize dispersed samples. The combination of dynamic light scattering and X-ray diffraction was used to estimate the thickness of the stabilizing layers of the polymer on the colloidal particles. Scattering of synchrotron radiation and neutrons are powerful complementary techniques to provide information about flow and the potential to apply them to systems that are beyond the scope of simple simulations has been demonstrated.

Todays conventional electronic devices are based on electron charge transport in semiconductor channels. Spintronics is a rapidly emerging technology, which exploits the spin degree of freedom as well as the charge of the electrons. It is believed that extending conventional electronics to spin-electronics can yield devices with new functionality and result in new large scale applications. Examples of already existing spintronic technology are the magnetic random access memory, magneto-resistive read heads in hard drives and various magnetic field sensors. The fundamental requirement for a working spintronic device is the ability to generate, transport and detect spin currents, which are the subject of this thesis. A current, spin polarized by a ferromagnet and injected into a non-magnetic material remains polarized for the duration of the spin relaxation time. This relaxation time, and consequently the useful distance the injected non-equilibrium spin can be transported in the non-magnetic transport channel, is dependent on the underlying spin relaxation mechanisms in the material. Furthermore, the transport channel can be deviced to exploit the spin-orbit scattering within the channel with the aim to achieve novel spin transport effects, such as the Spin Hall effect. We study such mechanisms and effects in normal and superconducting nanowires. The main results of the work are the following: In thin film devices, the thickness of the electron transport channel can be comparable to the electron's mean free path, which makes the surface scattering the dominant scattering mechanism. To investigate how the additional surface momentum scattering affects spin relaxation, the thickness dependence of the spin relaxation parameters was analyzed. Using spin injection into Al nanowires of various thickness, it was found that the spin flip scattering at the surfaces is substantially weaker compared to that within the bulk of Al. A five terminal device having a pair of spin sensitive detector electrodes placed symmetrically about the injection point was used to directly demonstrate the decoupling of spin and charge currents in a one-dimensional transport channel. The spin accumulation is shown to be strictly symmetric about the injection point and independent of the direction of the charge current. For superconducting nanowires, it is found that the spin accumulation is enhanced by up to 5 orders of magnitude compared to that in the normal state of the wire. In contrast, the spin diffusion length is found to decrease by an order of magnitude on transition in to the superconducting state. This is interpreted as due to magnetic impurity rather than spin-orbit dominated spin-flip scattering in the nanowires studied. We additionally observe a giant spin Hall effect in superconductors, which is more than 5 orders of magnitude stronger than the values reported recently for Al nanowires in the normal state. / QC 20100813

Computer simulation has become an important tool for the study of biomolecular systems. This thesis deals with molecular dynamics simulations of one-component lipid bilayers, which may serve as models for biological membranes. The main scientific contributions are: • It is possible to analyze the electrostatic contribution to the surface tension at a lipid-water interface in terms of dipole-dipole interactions between lipid headgroup shielded by a dielectric medium (water). The interaction can be divided into two parts. The in-plane components of the dipoles give rise to a positive, i.e. contractive contribution to the surface tension, albeit rather short ranged due to them being fluctuating dipoles. The normal components give rise to a negative, i.e. expansive contribution that will dominate the interaction at large distances. • Simulated membrane areas are extremely sensitive to details, especially the treatment of long-range electrostatic interactions. When cut-offs are used for the electrostatics, the exact definition of charge groups play an important role. Furthermore, using Ewald summation for the long-range interactions seems to have an overall stabilizing effect, and the area becomes less sensitive to other factors, such as system size and hydration. • Using atomistic simulations it is possible to study formation and evolution of a hydrophilic trans-membrane pore in detail. Free energy of pore nucleation and expansion can be calculated using potentials of mean constraint force. The resulting free energy profile shows no local maximum between the intact and pre-pore states, contrary to what is suggested by experiments. • The present force field reproduces even the slowest dynamics in the lipid chains, as reflected in NMR relaxation rates. Furthermore, since the simulated system was relatively small, the experimentally observed variation of relaxation rates with Larmor frequency cannot be explained by large scale collective dynamics, or it would not have shown up in the simulation. • Lipid lateral diffusion can be studied in detail on all relevant time scales by molecular dynamics. Using simple assumptions, the different diffusion coefficients measured on short and long times respectively can be connected in an analytic expression that fit calculated mean square displacements on timescales ranging from picoseconds to hundreds of nanoseconds. / QC 20100927

Lic.-avh. Luleå : Luleå tekniska univ., 2005.

Diss. Linköping : Univ., 2003.