This thesis concerns paper and ink interactions related to inkjet printing. The main purpose of this work was to gain a deeper understanding in which parameters control the flow of ink into papers and how the ink interacts with the paper surface. The overall objective was to find key parameters to optimize the print quality in inkjet printing. Characterization of paper-surfaces in terms of porosity, surface roughness and surface energy was made. Objective and subjective measurements were used for print quality evaluation. Light microscopy imaging and SEM was used to see how ink interacts with the paper surface in a printed image. A high speed camera was used to study the absorption of picolitre sized inkjet droplets into fine papers. An initial study on the effect of paper properties on print quality was made. Result indicated that there were small differences in print quality for pilot papers with different composition (in a specific parameter window) and the commercial paper COLORLOK® reproduced a noticeable high colour gamut compared to the other samples.Research was made to see how surface fixation can affect the print quality for printouts made with pigmented ink. Surface fixation promotes retention of the pigmented colorant in the outermost surface layer of the paper and has been denoted “colorant fixation” in this thesis. It was shown that applying colorant fixation onto a paper surface before printing can increase the detail reproduction in a printed image. Different concentrations of calcium chloride were applied onto the paper surface on fullscale produced non-commercial papers. Test printing was made with a SoHo (Small office/Home office) printer using pigmented ink and results showed that using calcium chloride as surface treatment can lead to aggregation of pigments at the surface resulting in a higher detail reproduction. Fast absorption of the carrier liquid into the paper and fast fixation of colourants on the surface is important in inkjet printing to avoid colour to colour bleeding. These demands will be more pronounced when the printing speed increases. It is important to understand which parameters affect the absorption process to be able to control the mechanisms and to optimize the print quality. A study of absorption of picolitre size inkjet droplets into fine paper was made in this work. Theoretical equations describing fluid absorption into capillaries were tested and compared with experimental results. The result showed that the time dependence in the Lucas-Washburn (L-W) equation fits fairly well to data whereas the L-W equation overestimates the penetration depth. The results are directly applicable to paper and printing industry and can be used as a base for future studies of absorption of picolitre sized droplets into porous materials and for studies of aggregation of colloidal particles on surfaces. / Presentationen hölls den 2011-02-25 / Next generation substrates for inkjet printing

In this thesis, we present results from detailed gas phase studies of intrinsic properties of fullerenes (C60) and clusters of fullerenes as probed by slow multiply charged (atomic or cluster) ions in combination with coincidence time-of-flight mass spectrometry. We have investigated the structures, stabilities, and the electron mobilities of multiply charged clusters of fullerenes, (C60)nr+ (r=2-5). We found that the (C60)nr+ cluster ions are weakly bound by van der Waals forces and the electric conductivity is high in strong contrast to the typical characteristics of other van der Waals type clusters and fullerene crystals (fullerite), where the charge is strongly localized. The high charge mobility was rationalized within the framework of a novel classical static over-the-barrier model for two conducting spheres used to describe multiple charge transfer processes between two neighboring fullerenes in the cluster. The model results showed that electron transfer is possible as soon as the C60-C60 system is charged, consistent with earlier experimental results from slow C60q+ + C60 collisions where an electric contact is established (during the very short interaction time of the collision) between the two molecules at distances outside the binding distance in the C60-C60 system. The present electrostatic model was also used to guide the interpretation of the measured kinetic energy releases in the fragmentation of multiply charged dimers, (C60)2r+ → C60r1+ + C60r2+. In like manner, we have measured kinetic energy releases in the break-ups of multiply charged monomer fullerene ions with the aid of fragment-ion momentum spectroscopy. This yielded an excellent platform for investigations of the projectile and target dependencies on various intrinsic features such as the ultimate Coulomb stability limits for C60r+ and C70r+ ions, competition between different reaction pathways, and multi-fragmentation processes. The experimental results for the stability limits for multiply charged fullerenes are discussed in view of recent high level Density Functional Theory calculations of C60r+ → C58(r-1)+ + C2+ transition states and our electrostatic model. The Density Functional Theory results are also used to check the validity and limitations of the classical model regarding the description of fragmentation processes, while a comparison with advanced molecular dynamic calculations of Ar8++Na40 collisions were made for investigating its applicability for charge transfer processes. We found that the present model indeed is useful for describing main features in inherent complex molecular processes at sufficiently low collision velocities. In addition, we propose an extension of the present model to consider two dielectric spheres immersed in a dielectric medium, which might be applied also outside the cluster research field.

No description available.

An all-pervading feature of the work presented in this thesis is the study of ultrafast dynamics, both theoretically and experimentally, in terms of time-dependent wave functions (wave packets). We have experimentally, by pump-probe fluorescence spectroscopy, examined spin-orbit interactions, by time-tracing molecular wave packets on excited states of diatomic rubidium, and the main channels causing the fast predissociation from one of those states is revealed. The time evolution of wave packets and their extension in space, in addition to varying transition dipole moment is of specific interest in the semiclassically derived expressions for the total ion signal, in the context of pump-probe ionization spectroscopy on diatomic molecules. We have experimentally, by pump-probe fluorescence spectroscopy, addressed a previously derived theoretical prediction about level interactions between atomic levels with all angular momentum quantum numbers equal but different principal quantum numbers. Hence, the ultrafast progression of atomic radial wave packets are disclosed in terms of quantum beat frequencies and explained theoretically in the context of pump-probe fluorescence spectroscopy. Preliminary fluorescence up-conversion experiments are as well treated in this thesis with the aim to reveal further experimental knowledge on the previously derived theoretical prediction on the specific level interactions mentioned above.

This thesis adresses electric and magnetic noise and dissipation in magnetoelectronic nanostructures. Charge and spin current fluctuations are studied in various nanosized metallic structures consisting of both ferromagnetic and non-magnetic elements. The interplay between current and magnetization fluctuations, and the relation of these fluctuations to the electric and magnetic dissipation of energy, are considered. Special focus is on the enhancement of magnetization damping due to so-called spin pumping, which is shown to be directly connected to thermal spin current fluctuations. Two fundamental sources of current noise are considered: Thermal noise and shot noise. Since a spin current polarized transverse to the magnetization is absorbed in a ferromagnet, transverse spin current fluctuations exert a fluctuating torque on the magnetization. This spin-transfer torque causes significant magnetization fluctuations in nanoscale ferromagnets. In single-domain ferromagnets in contact with normal electric conductors, the spin-current induced magnetization noise is directly connected to the magnetization damping caused by spin pumping. In non-uniformly magnetized ferromagnets, the spin-current induced magnetization noise is related to a nonlocal tensor damping that reflects the spatial variation of the magnetization. At low temperatures, spin current shot noise in the presence of an applied bias is the dominant contribution to the magnetization noise. In spin valves, two ferromagnets are separated by a thin normal metal spacer. The interaction of the ferromagnets affects their magnetization noise and damping, which are shown to vary with the relative magnetic orientation of the ferromagnets. Due to giant magnetoresistance, the magnetization fluctuations cause resistance noise. The resistance noise is identified as a prominent source of electric noise at relatively high current densities. The noise level can vary substantially with the relative magnetic orientation.

No description available.

An outstanding problem in physics is to find a unified framework for quantum mechanics and general relativity. This is required for a better understanding of black holes and the early cosmology of the universe. String theory provides such a unification. In this thesis, we study aspects of compactifications of type IIB string theory. In the first part of the thesis, we study four-dimensional black holes consisting of D3-branes wrapping cycles in the compact dimensions. We discuss the correspondence between these black holes, topological string theory and matrix models. We then study the influence of black holes on the stability of flux compactifications. In the second part of the thesis, we turn to investigations of the type IIB landscape, i.e. the collection of stable and metastable vacua obtained from flux compactifications on conformal Calabi-Yau manifolds. We show that monodromies are important for the topographic structure of the landscape. In particular we find that there are long series of continuously connected vacua in the complex structure moduli space of the internal manifold. We also use geometric transitions to connect the moduli spaces of different manifolds, and create longer series of vacua. Finally, we investigate the stability of string theory vacua by constructing semiclassical instantons. These results have implications for the population of the landscape by eternal inflation.

A new challenging application for Li-ion battery has arisen from the rapid development of micro-electronics. Powering Micro-ElectroMechanical Systems (MEMS) such as autonomous smart-dust nodes using conventional Li-ion batteries is not possible. It is not only new batteries based on new materials but there is also a need of modifying the actual battery design. In this context, the conception of 3D nano-architectured Li-ion batteries is explored. There are several micro-battery concepts that are studied; however in this thesis, the focus is concentrated on one particular architecture that can be described as the successive deposition of battery components (active material, electrolyte, active material) on free-standing arrays of nano-sized columns of a current collector. After a brief introduction about Li-ion batteries and 3D micro-batteries, the electrodeposition of Al through an alumina template using an ionic liquid electrolyte to form free-standing columns of Al current collector is described. The crucial deposition parameters influencing the nucleation and growth of the Al nano-rods are discussed. The deposition of active electrode material on the nano-structured current collector columns is described for 2 distinct active materials deposited using different techniques. Deposition of TiO2 using Atomic Layer Deposition (ALD) as active material on top of the nano-structured Al is also presented. The obtained deposits present high uniformity and high covering of the specific surface of the current collector. When cycled versus lithium and compared to planar electrodes, an increase of the capacity was proven to be directly proportional to the specific area gained from shifting from a 2D to a 3D construction. Cu2Sb 3D electrodes were prepared by the electrodeposition of Sb onto a nano-structured Cu current collector followed by an annealing step forcing the alloying between the current collector and Sb. The volume expansion observed during Sb alloying with Li is buffered by the Cu matrix and thus the electrode stability is greatly enhanced (from only 20 cycles to more than 120 cycles). Finally, the deposition of a hybrid polymer electrolyte onto the developed 3D electrodes is presented. Even though the deposition is not conformal and that issues of capacity fading need to be addressed, preliminary results attest that it is possible to cycle the obtained 3D electrode-electrolyte versus lithium without the appearance of short-circuits.

Materials with biotechnological applications and materials that interact with the biological environment play an ever increasing role in our lives and society. In order to be able to tailor specific properties of these materials to suit their intended applications, it is important to gain a deeper understanding of the relationship between the material structure and its function. This thesis contributes to the goal of achieving a better understanding of the functional properties of materials through the development of novel characterizing methods as well as the analysis of such materials. Electrodynamic and mechanical spectroscopy methods are developed or employed in the characterization of three classes of materials, namely, pharmaceutical, biomedical and biological materials. Two electrodynamic methods utilizing conductivity measurements were developed for the investigation of drug release from pharmaceutical dosage forms, particularly in low liquid volumes. Furthermore, a mechanical spectroscopy method based on the split Hopkinson pressure bar setup was developed for the viscoelastic characterization of pharmaceutical compacts. It was shown that this method is a valuable complement to other methods of characterization. Dielectric spectroscopy was integrated with microfabrication techniques to create a method for bacteria detection in a biotechnological application. As well, dielectric spectroscopy was used in the characterization of a novel biomimetic ionomer and was demonstrated to be a powerful tool for studying the bulk molecular dynamics of this functional material. The work presented in this thesis not only provides an enhanced understanding of materials and their functional properties, but also presents new methods that should be useful for the future characterization of such materials.

The use of ultrasonic standing waves for contactless manipulation of microparticles in microfluidic systems is a field with potential to become a new standard tool in lab-on-chip systems. Compared to other contactless manipulation methods ultrasonic standing wave manipulation shows promises of gentle cell handling, low cost, and precise temperature control. The technology can be used both for batch handling, such as sorting and aggregation, and handling of single particles. This doctoral Thesis presents multi-dimensional ultrasonic manipulation, i.e., manipulation in both two and three spatial dimensions as well as time-dependent manipulation of living cells and microbeads in microfluidic systems. The lab-on-chip structures used allow for high-quality optical microscopy, which is central to many bio-applications. It is demonstrated how the ultrasonic force fields can be spatially confined to predefined regions in the system, enabling sequential manipulation functions. Furthermore, it is shown how frequency-modulated signals can be used both for spatial stabilization of the force fields as well as for flow-free transport of particles in a microchannel. Design parameters of the chip-transducer systems employed are investigated experimentally as well as by numerical simulations. It is shown that three-dimensional resonances in the solid structure of the chip strongly influences the resonance shaping in the channel. / QC 20100730