Infrared spectroscopy of physisorbed and chemisorbed N-2 in the Pt(111)(3x3)N-2 structure

Using infrared spectroscopy and low electron energy diffraction, we have investigated the adsorption of N-2, at 30 K, on the Pt(111) and the Pt(111)(1x1)H surfaces. At monolayer coverage, N-2 orders in commensurate (3x3) structures on both surfaces, and we propose that the unit cells contain four molecules in each case. The infrared spectra reveal that N-2 exclusively physisorbs on the Pt(111)(1x1)H surface, while both physisorbed and chemisorbed N-2 is detected on the Pt(111) surface. Physisorbed N-2 is the majority species in the latter case, and the two adsorption states show an almost identical uptake behavior, which indicates that they are intrinsic constituents of the growing (3x3) N-2 islands. An analysis of the infrared absorbance data, based on a simple scaling concept suggested by density functional theory calculations, supports a model in which the (3x3) unit cell contains one chemisorbed molecule in end-on atop configuration and three physisorbed molecules. We note that a classic ''pinwheel'' structure on a hexagonal lattice, with the end-on chemisorbed N2 molecules acting as ''pins,'' is compatible with this composition. (C) 2007 American Institute of Physics

Misslyckande trots numerär överlägsenhet : en teorikonsumerande studie om luftoperativ kontroll under Falklandskriget

This study examines how Argentina’s failure to obtain control of the air during the Falklands war can be explained based on the theories of John A. Warden and Philip S. Meilinger. The failure is problematic due to the numerical superiority and geographical advantage of the Argentinian Air Force. Previous studies have focused on the absence of airborne early warning, air-to-sea warfare and the perspective of Clausewitz theories. The purpose of this study is therefore the to develop a theory-based explanation of the Argentinian failure from the perspective of two air-warfare theories. The first day of the war (May 1) and the landing on the shores of San Carlos constitute crucial parts of the air war. The paper utilizes a theory consuming approach to explain the two cases and then comparing them to develop an aggregated explanation of the Argentinian failure. The result of the analysis is that Argentinian failure to identify and attack Britain’s aircraft carriers/landing ships, failure to concentrate the offensive operations and selective British air defence are key parts of the explanation. The results contributes to a deeper understanding of a perspective of the Falklands air war that has not been analysed in previously analysed in earlier academic studies.   

Catalytic Water Production from First-Principles Calculations

The main subject of this thesis is the catalytic water production reaction on metal surfaces. This reaction is of great current interest due to its importance in fuel cells, a clean and efficient way to convert chemical energy into electrical. Fuel cells constitute a vital part in a remedy to the pressing environmental issue of the increasing green house effect, and may furthermore be used as a convenient and powerful replacement to conventional batteries in mobile applications such as cellular phones and computers. A strong connection also exists between the water production reaction and processes occurring in corrosion and electrochemistry. In particular, similar mixtures of water and hydroxyl are expected in all these cases. This thesis studies the catalytic water production reaction on metal surfaces using first-principles based calculations at the quantum-mechanical level within the framework of density functional theory. Extension to both equilibrium and kinetic properties of larger length scale adsorbate structures are provided by Monte Carlo calculations. In particular, the work focuses on the following parts: (i) A quantum treatment of hydrogen adsorbed on Pt(111). (ii) The nature and properties of the low temperature intermediate in the catalytic water production reaction on Pt(111). This intermediate turns out to consist of a mixture of water and hydroxyl adsorbed on the surface. An extensive model to simulate large length scale thermodynamics and kinetics for mixed water and hydroxyl overlayers is developed. (iii) Adsorption trends for the water, hydroxyl, oxygen and hydrogen on transition metal surfaces are studied. Taken together the results yield a fundamental understanding of the water production reaction and water related adsorbate-adsorbate interaction on metal surfaces. In particular, the strength and directional character of the hydrogen bonds in these structures are analyzed. Of all hydrogen bonds in this study the ones occurring between hydroxyl and water are found to be the strongest. A directional asymmetry in the hydrogen bond strength is found for adsorbed hydroxyl molecules. Processes such as proton transport and hydroxyl decomposition are studied for the water-hydroxyl mixed overlayers. Foundations for generalizing the results are provided by adsorption trends on metals close to platinum in the periodic table. From the trend study it is among others found that the topmost metal layer in the substrate dominates the adsorption characteristics

Catalytic Water Production from First-Principles Calculations

The main subject of this thesis is the catalytic water production reaction on metal surfaces. This reaction is of great current interest due to its importance in fuel cells, a clean and efficient way to convert chemical energy into electrical. Fuel cells constitute a vital part in a remedy to the pressing environmental issue of the increasing green house effect, and may furthermore be used as a convenient and powerful replacement to conventional batteries in mobile applications such as cellular phones and computers. A strong connection also exists between the water production reaction and processes occurring in corrosion and electrochemistry. In particular, similar mixtures of water and hydroxyl are expected in all these cases. This thesis studies the catalytic water production reaction on metal surfaces using first-principles based calculations at the quantum-mechanical level within the framework of density functional theory. Extension to both equilibrium and kinetic properties of larger length scale adsorbate structures are provided by Monte Carlo calculations. In particular, the work focuses on the following parts: (i) A quantum treatment of hydrogen adsorbed on Pt(111). (ii) The nature and properties of the low temperature intermediate in the catalytic water production reaction on Pt(111). This intermediate turns out to consist of a mixture of water and hydroxyl adsorbed on the surface. An extensive model to simulate large length scale thermodynamics and kinetics for mixed water and hydroxyl overlayers is developed. (iii) Adsorption trends for the water, hydroxyl, oxygen and hydrogen on transition metal surfaces are studied. Taken together the results yield a fundamental understanding of the water production reaction and water related adsorbate-adsorbate interaction on metal surfaces. In particular, the strength and directional character of the hydrogen bonds in these structures are analyzed. Of all hydrogen bonds in this study the ones occurring between hydroxyl and water are found to be the strongest. A directional asymmetry in the hydrogen bond strength is found for adsorbed hydroxyl molecules. Processes such as proton transport and hydroxyl decomposition are studied for the water-hydroxyl mixed overlayers. Foundations for generalizing the results are provided by adsorption trends on metals close to platinum in the periodic table. From the trend study it is among others found that the topmost metal layer in the substrate dominates the adsorption characteristics

Commercialization Challenges in Green Tech

In recent years, pressures for making society more sustainable have been on a constant increase, and many of the new green technology solutions which will facilitate this change are likely to originate from small high-tech firms. However, young technology-based firms often fail to successfully bring their products to the market – a process known as commercialization. The purpose of this study was to from a managerial perspective contribute to narrowing the gap between practice and academia in the largely unexplored area of commercializing green tech. A qualitative study using an abductive research approach was conducted based on semi-structured interviews carried out at five Swedish green tech companies, followed by an analysis based on grounded theory. From this, four main challenges of green tech commercialization in Sweden were identified, including the reliance of green tech firms on external actors, challenges related to attracting employees and partners, the risk of green tech markets not materializing, and difficulties related to securing financing. Additionally, four underlying themes connected to these challenges were discussed, including issues related to the apparent interrelatedness of green tech markets, the importance of policy support to green tech viability, the importance of investor support, and issues related to gaining trust