Abstract: In this paper, new insights of the photocatalytic oxidation pathway of acetaldehyde are obtained by means of an in-house constructed FTIR in situ reactor. It is shown that there are generally three different intermediates present: acetic acid, formic acid and formaldehyde. By means of FTIR in situ spectroscopy, this study revealed that these intermediates are bound on the TiO2 surface in different ways, resulting in the presence of more intermediate species, such as molecularly adsorbed acetic acid, bidentate acetate, molecularly adsorbed formic acid, monodentate formate, bidentate formate, formaldehyde and dioxymethylene. Furthermore, spectroscopic evidence is obtained concerning the formation of 3-hydroxybutanal and crotonaldehyde upon adsorption of acetaldehyde on TiO2 prior to UV illumination. The presented results thus give new insights in the photocatalytic oxidation pathway of acetaldehyde.

Abstract: In this paper, an overview of the fabrication and properties of high-quality La0.67Sr0.33MnO3 (LSMO) thin films is given. A high-quality LSMO film combines a smooth surface morphology with a large magnetization and a small residual resistivity, while avoiding precipitates and surface segregation. In the literature, typically only a few of these issues are adressed. We therefore present a thorough characterization of our films, which were grown by pulsed laser deposition. The films were characterized with reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction, magnetization and transport measurements, x-ray photoelectron spectroscopy and scanning transmission electron microscopy. The films have a saturation magnetization of 4.0 µB/Mn, a Curie temperature of 350 K and a residual resistivity of 60 µΩ cm. These results indicate that high-quality films, combining both large magnetization and small residual resistivity, were realized. A comparison between different samples presented in the literature shows that focussing on a single property is insufficient for the optimization of the deposition process. For high-quality films, all properties have to be adressed. For LSMO devices, the thin-film quality is crucial for the device performance. Therefore, this research is important for the application of LSMO in devices.

Abstract: In this paper, an overview is given of modeling activities going on in our research group, for describing the plasma chemistry and plasmasurface interactions in reactive plasmas. The plasma chemistry is calculated by a fluid approach or by hybrid Monte Carlo (MC)fluid modeling. An example of both is illustrated in the first part of the paper. The example of fluid modeling is given for a dielectric barrier discharge (DBD) in CH4/O2, to describe the partial oxidation of CH4 into value-added chemicals. The example of hybrid MCfluid modeling concerns an inductively coupled plasma (ICP) etch reactor in Ar/Cl2/O2, including also the description of the etch process. The second part of the paper deals with the treatment of plasmasurface interactions on the atomic level, with molecular dynamics (MD) simulations or a combination of MD and MC simulations.

Abstract: In this paper, an O2 inductively coupled plasma used for plasma enhanced atomic layer deposition of Al2O3 thin films is investigated by means of modeling. This work intends to provide more information about basic plasma properties such as species densities and species fluxes to the substrate as a function of power and pressure, which might be hard to measure experimentally. For this purpose, a hybrid model developed by Kushner et al is applied to calculate the plasma characteristics in the reactor volume for different chamber pressures ranging from 1 to 10 mTorr and different coil powers ranging from 50 to 500 W. Density profiles of the various oxygen containing plasma species are reported as well as fluxes to the substrate under various operating conditions. Furthermore, different orientations of the substrate, which can be placed vertically or horizontally in the reactor, are taken into account. In addition, special attention is paid to the recombination process of atomic oxygen on the different reactor walls under the stated operating conditions. From this work it can be concluded that the plasma properties change significantly in different locations of the reactor. The plasma density near the cylindrical coil is high, while it is almost negligible in the neighborhood of the substrate. Ion and excited species fluxes to the substrate are found to be very low and negligible. Finally, the orientation of the substrate has a minor effect on the flux of O2, while it has a significant effect on the flux of O. In the horizontal configuration, the flux of atomic oxygen can be up to one order of magnitude lower than in the vertical configuration.

Abstract: In this paper, a self-consistent fluid model is developed focusing on the plasma parameters in capacitively coupled 20% N 2-80% Ar discharges. Measurements of ion density are performed with the help of a floating double probe, and the emission intensities from Ar(4p) and N 2 ( B ) transitions are detected by an optical emission spectroscopy to estimate their relative densities. The consistency between the numerical and experimental results confirms the reliability of the simulation. Then the plasma characteristics, specifically the reaction mechanisms of active species, are analyzed under various voltages. The increasing voltage leads to a monotonous increase in species density, whereas a less homogeneous radial distribution is observed at a higher voltage. Due to the high concentration of Ar gas, Ar + becomes the main ion, followed by the N 2 +</mml:msubsup> ion. Besides the electron impact ionization of neutrals, the charge transfer processes of Ar +/ N 2 and N 2 +</mml:msubsup>/Ar are found to have an impact on the ionic species. The results indicate that adopting the lower charge transfer reaction rate coefficients weakens the Ar + ion density and yields a higher N 2 +</mml:msubsup> ion density. However, the effect on the species spatial distributions and other species densities is limited. As for the excited-state species, the electron impact excitation of background gases remains overwhelming in the formation of Ar(4p), N 2 ( B ), and N 2 ( a ' ), whereas the <mml:msub> N 2 ( A ) molecules are mainly formed by the decay of <mml:msub> N 2 ( B ). In addition, the dissociation of <mml:msub> N 2 collided by excited-state Ar atoms dominates the N generation, which are mostly depleted to produce N + ions.

Abstract: In this paper, a new fouling measurement method is presented as a pragmatic approach to determine a mixed liquor's fouling propensity. The MBR-VFM (VITO Fouling Measurement) uses a specific measurement protocol consisting of alternating filtration and physical cleaning steps, which enables the calculation of both the reversible and the irreversible fouling resistances. The MBR-VFM principle, set-up and measurement protocol are described as well as the evaluation of the fouling measurement method. Finally, the MBR-VFM was validated by comparing the fouling propensity measured on-line by the MBR-VFM in a lab-scale MBR with the fouling of the MBR membranes themselves. Our experiments indicated that the MBR-VFM can accurately measure fouling and that it can even be detected earlier than can be seen from the on-line filtration data of the lab-scale system itself. Furthermore, the differences measured in reversible and irreversible fouling seemed to be related to the observed impact of physical and chemical cleaning respectively. Therefore, the application of the MBR-VFM as an on-line sensor in an advanced control system, enabling the deployment of the measured fouling data for the control of membrane cleaning, seems feasible and will be tested in the near future.

Abstract: In this paper we used a one dimensional fluid model, for the simulations of a Dielectric Barrier Discharge at atmospheric pressure. From the current and voltage profiles and the density profiles, we notice that two different regimes can be obtained in a uniform DBD. Furthermore a two dimensional flud model was developed and we describe how the gasflow can be included in such a model.

Abstract: In this paper we study the cold atmospheric pressure plasma jet, called kinpen, operating in Ar with different admixture fractions up to 1% pure , and + . Moreover, the device is operating with a gas curtain of dry air. The absolute net production rates of the biologically active ozone () and nitrogen dioxide () species are measured in the far effluent by quantum cascade laser absorption spectroscopy in the mid-infrared. Additionally, a zero-dimensional semi-empirical reaction kinetics model is used to calculate the net production rates of these reactive molecules, which are compared to the experimental data. The latter model is applied throughout the entire plasma jet, starting already within the device itself. Very good qualitative and even quantitative agreement between the calculated and measured data is demonstrated. The numerical model thus yields very useful information about the chemical pathways of both the and the generation. It is shown that the production of these species can be manipulated by up to one order of magnitude by varying the amount of admixture or the admixture type, since this affects the electron kinetics significantly at these low concentration levels.

Abstract: In this paper we study dry reforming of methane (DRM) in a gliding arc plasmatron (GAP) in the presence of N₂and O₂. N₂is added to create a stable plasma at equal fractions of CO₂and CH₄, and because emissions from industrial plants typically contain N₂, while O₂is added to enhance the process. We test different gas mixing ratios to evaluate the conversion and energy cost. We obtain conversions between 31 and 52% for CO₂and between 55 and 99% for CH₄, with total energy costs between 3.4 and 5.0 eV per molecule, depending on the gas mixture. This is very competitive when benchmarked with the literature. In addition, we present a chemical kinetics model to obtain deeper insight in the underlying plasma chemistry. This allows determination of the major reaction pathways to convert CO₂and CH₄, in the presence of O₂and N₂, into CO and H₂. We show that N₂assists in the CO₂conversion, but part of the applied energy is also wasted in N₂excitation. Adding O₂enhances the CH₄conversion, and lowers the energy cost, while the CO₂conversion remains constant, and only slightly drops at the highest O₂fractions studied, when CH₄is fully oxidized into CO₂.

Abstract: In this paper we review the work related to amorphization under mechanical stress. Beyond pressure, we highlight the role of deviatoric or shear stresses. We show that the most recent works make amorphization appear as a deformation mechanism in its own right, in particular under extreme conditions (shocks, deformations under high stresses, high strain-rates).

Abstract: In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose׳s legacy in aberration correction and electron optics in general would open an exciting field of research and applications.

Abstract: In this paper we demonstrate that by means of scanning reflection FTIR spectroscopy, it is possible to record highly specific distribution maps of organic and inorganic compounds from flat, macroscopic objects with cultural heritage value in a non-invasive manner. Our previous work involved the recording of macroscopic distributions of chemical elements or crystal phases from painted works of art based on respectively macroscopic X-ray fluorescence or X-ray powder diffraction analysis. The use of infrared radiation instead of X-rays has the advantage that more specific information about the nature and distribution of the chemical compounds present can be gathered. This higher imaging specificity represents a clear advantage for the characterization of painting and artist materials. It allows the distribution of metallo-organic compounds to be visualized and permits distinguishing between pigmented materials containing the same key metal. The prototype instrument allows the recording of hyperspectral datacubes by scanning the surface of the artefact in a contactless and sequential single-point measuring mode, while recording the spectrum of reflected infrared radiation. After the acquisition, spectral line intensities of individual bands and chemical distribution maps can be extracted from the datacube to identify the compounds present and/or to highlight their spatial distribution. Not only is information gained on the surface of the investigated artefacts, but also images of overpainted paint layers and, if present, the underdrawing may be revealed in this manner. A current major limitation is the long scanning times required to record these maps.

Abstract: In this paper the various elementary plasma—surface interaction processes occurring in plasma catalysis are critically evaluated. Specifically, plasma catalysis at atmospheric pressure is considered. The importance of the various processes is analyzed for the most common plasma catalysis sources, viz. the dielectric barrier discharge and the gliding arc. The role and importance of surface chemical reactions (including adsorption, surface-mediated association and dissociation reactions, and desorption), plasma-induced surface modification, photocatalyst activation, heating, charging, surface discharge formation and electric field enhancement are discussed in the context of plasma catalysis. Numerous examples are provided to demonstrate the importance of the various processes.

Abstract: In this paper the luminescence of the scheelite-based CaGd2(1-x)Eu2x(WO4)4 solid solutions is investigated as a function of the Eu content and temperature. All phosphors show intense red luminescence due to the 5D0 7F2 transition in Eu3+, along with other transitions from the 5D1 and 5D0 excited states. For high Eu3+ concentrations the intensity ratio of the emission originating from the 5D1 and 5D0 levels has a non-conventional temperature dependence, which could be explained by a phonon-assisted cross-relaxation process. It is demonstrated that this intensity ratio can be used as a measure of temperature with high spatial resolution, allowing the use of these scheelites as thermographic phosphor. The main disadvantage of many thermographic phosphors, a decreasing signal for increasing temperature, is absent.

Abstract: In this paper electrodeposition is used to obtain Cu nanoparticles, as it allows good control over particle size and distribution. These Cu particles were deposited onto a gas diffusion electrode which increased the resulting surface area. Prior to deposition, the surface was pre-treated with NaOH, HNO3, MQ and TX100 to investigate the influence on the electrodeposition of Cu on the gas diffusion electrode (GDE). When using HNO3, the smallest particles with the most homogeneous distribution and high particle roughness were obtained. Once the optimal substrate was determined, we further demonstrated that by altering the electrodeposition parameters, the particle size and density could be tuned. On the one hand, increasing the nucleation potential led to a higher particle density resulting in smaller particles because of an increased competition between particles. Finally, the Cu particle size increased when applying a greater growth charge and growth potential. This fundamental study thus opens up a path towards the synthesis of supported Cu materials with increased surface areas, which is interesting from a catalytic point of view. Larger surface areas are generally correlated with a better catalyst performance and thus higher product yields. This research can contributed in obtaining new insides into the deposition of metallic nanoparticles on rough surfaces. [GRAPHICS] .