This thesis describes the approach and results of the research to create a TRIZ based computer aided innovation tools (AEGIS and Design for Wow). This research has mainly been based around two tools created under this research: called AEGIS (Accelerated Evolutionary Graphics Interface System), and Design for Wow. Both of these tools are discussed in this thesis in detail, along with the test data, design methodology, test cases, and research. Design for Wow (http://www.designforwow.com) is an attempt to summarize the successful inventions/ designs from all over the world on a web portal which has multiple capabilities. These designs/innovations are then linked to the TRIZ Principles in order to determine whether innovative aspects of these successful innovations are fully covered by the forty TRIZ principles. In Design for Wow, a framework is created which is implemented through a review tool. The Design for Wow website includes this tool which has been used by researcher and the users of the site and reviewers to analyse the uploaded data in terms of strength of TRIZ Principles linked to them. AEGIS (Accelerated Evolutionary Graphics Interface System) is a software tool developed under this research aimed to help the graphic designers to make innovative graphic designs. Again it uses the forty TRIZ Principles as a set of guiding rules in the software. AEGIS creates graphic design prototypes according to the user input and uses TRIZ Principles framework as a guide to generate innovative graphic design samples. The AEGIS tool created is based on TRIZ Principles discussed in Chapter 3 (a subset of them). In AEGIS, the TRIZ Principles are used to create innovative graphic design effects. The literature review on innovative graphic design (in chapter 3) has been analysed for links with TRIZ Principles and then the DNA of AEGIS has been built on the basis of this study. Results from various surveys/ questionnaires indicated were used to collect the innovative graphic design samples and then TRIZ was mapped to it (see section 3.2). The TRIZ effects were mapped to the basic graphic design elements and the anatomy of the graphic design letters was studied to analyse the TRIZ effects in the collected samples. This study was used to build the TRIZ based AEGIS tool. Hence, AEGIS tool applies the innovative effects using TRIZ to basic graphic design elements (as described in section 3.3). the working of AEGIS is designed based on Genetic Algorithms coded specifically to implement TRIZ Principles specialized for Graphic Design, chapter 4 discusses the process followed to apply TRIZ Principles to graphic design and coding them using Genetic Algorithms, hence resulting in AEGIS tool. Similarly, in Design for Wow, the content uploaded has been analysed for its link with TRIZ Principles (see section 3.1 for TRIZ Principles). The tool created in Design for Wow is based on the framework of analysing the TRIZ links in the uploaded content. The ‘Wow’ concept discussed in the section 5.1 and 5.2 is the basis of the concept of Design for Wow website, whereby the users upload the content they classify as ‘Wow’. This content then is further analysed for the ‘Wow factor’ and then mapped to TRIZ Principles as TRIZ tagging methodology is framed (section 5.5). From the results of the research, it appears that the TRIZ Principles are a comprehensive set of innovation basic building blocks. Some surveys suggest that amongst other tools, TRIZ Principles were the first choice and used most .They have thus the potential of being used in other innovation domains, to help in their analysis, understanding and potential development.

Die ultrakalte Atom- und Molekülephysik, zu welcher man zum Beispiel bei der Bose-Einstein-Kondensation von verdünnten Gasen Zugang hat, wurde untersucht. In solchen Systemen dominieren Zwei-Körper-Stöße und ihre detaillierte Untersuchung ist eines der zentralen Themen dieser Arbeit. Diese wurden durchgeführt unter Berücksichtigung von elementaren chemischen Reaktionen, Photoassoziation und magnetischen Feshbach-Resonanzen. Weiterhin wurden Untersuchungen von Atomen in optischen Gittern durchgeführt. Die Viel-Teilchen-Systeme wurden nicht nur mit dem üblichen mean-field Ansatz behandelt, sondern auch darüber hinausgehend, um die voll korrelierte Bewegung zu simulieren. / The ultracold atomic and molecular physics as it is accessible, e.g., in Bose-Einstein condensates of dilute gases was investigated. In such systems two-body collisions are dominant and their detailed study is one of the central topics of this work. They were done considering elementary chemical reactions as photoassociation, and magnetic Feshbach resonances. Additionally, studies of atoms in optical lattice sites were carried out. The many-body systems were not only considered within the usually adopted mean-field approach but also beyond that in order to simulate the fully correlated motion.

Cocristais fármaco-fármaco envolvem a junção de dois ou mais insumos farmacêuticos ativos (IFAs), preservando seu caráter neutro e sem a necessidade de quebra ou formação de ligação covalente, mantendo desta maneira sua eficácia. Propriedades dos IFAs em estado sólido, como as interações entre grupos farmacofóricos e receptores, são determinadas pela polaridade dos grupos funcionais e potencial eletrostático assim como pelas interações intermoleculares, que por sua vez dependem das características eletrônicas e moleculares do arranjo tridimensional. Propriedades eletrônicas moleculares e sua relação com a topologia da densidade de carga eletrônica é parte dos estudos teóricos apresentados neste trabalho. Estes estudos envolvem cálculos da distribuição da densidade de carga eletrônica e sua topologia por meio da Teoria Quântica de Átomos em Moléculas AIM (do inglês, atoms in molecules) de Bader. Neste contexto, o presente trabalho apresentou cálculos teóricos da densidade de carga em um sistema periódico tridimensional, utilizando como modelo de partida os dados cristalográficos do cocristal fármaco-fármaco constituído da 5-Fluorocitosina (antimetabólito) e da Isoniazida (tuberculostático), nomeado por 5FC-INH. A função de onda deste sistema foi calculada por meio da teoria do funcional da densidade DFT (do inglês, density functional theory), com alguns níveis de teoria em conjunto com funções de base, utilizando o pacote de programas CRYSTAL14. A distribuição da densidade de carga, resultante destes cálculos, foi analisada por meio da AIM utilizando alguns descritores topológicos, como densidade de carga, Laplaciano da densidade de carga e a elipticidade nos pontos críticos das ligações de enlace covalentes e as interações intermoleculares da unidade assimétrica. Uma análise preliminar dos valores da densidade de carga eletrônica, calculada nos pontos críticos de ligação da 5FC-INH, permitiu selecionar o nível de teoria e conjunto de funções base que melhor reproduziu os dados experimentais, como sendo o B3LYP/6-311++G**. Os valores dos descritores, obtidos dos cálculos com este nível de teoria, foram comparados com os provenientes dos experimentos de difração de raios X de alta resolução e resultaram em boa concordância na descrição da topologia da densidade de carga eletrônica. Os descritores apresentaram valores muito próximos dos reportados na literatura para os grupos funcionais da 5-FC e da INH. Imagens dos mapas das trajetórias do gradiente e do Laplaciano da densidade de carga, dos caminhos de ligação e dos contornos das bacias atômicas, permitiram visualizar as regiões de depleção e acúmulo da densidade de carga. Por meio destas representações foi possível descrever as ligações de hidrogênio responsáveis pela estabilização do cocristal, as ligações químicas covalentes, as deformações das bacias atômicas que caracterizam as polarizações e os mapas do Laplaciano que permitem observar os pares solitários de elétrons, como dos átomos de flúor, oxigênio e nitrogênio. / Drug-drug cocrystals involve the formation of crystals of two or more active pharmaceutical ingredients (APIs) preserving their original chemical characteristics since no breakage or formation of covalent bonds is observed, thus maintaining their effectiveness. APIs solid state properties, such as pharmacophoric and receptor group interactions are determined by the polarity of functional groups, electrostatic potential and potential intermolecular interactions, which in turn depend on the electronic and molecular characteristics of the three-dimensional arrangement. Molecular electron properties and their relationship with charge density topology is part of the theoretical studies presented in this dissertation. These studies involve electron charge density distribution calculations and their topology through the Bader’s quantum theory of atoms in molecules (AIM). To that aim, the present work presents theoretical calculations of the charge density in a three-dimensional periodic system, using crystallographic data of the drug-drug cocrystal involving the antimetabolite prodrug 5-Fluorocytosine (5-FC) and the tuberculostatic drug Isoniazid (INH), namely, 5FC-INH, as a starting model. The wave function of this system was calculated through density functional theory (DFT), with some levels of theory together with an adequate basis set, using the CRYSTAL14 program package. The charge density distribution resulting from these calculations was analyzed for the asymmetric unit using the AIM model where topological descriptors such as charge density, charge density Laplacian and ellipticity at bond critical points (for covalent bonds and intermolecular interactions). A preliminary analysis of the electronic charge density values, calculated at the bond critical points of 5FC-INH, allowed us to select the level of theory and basis set that best reproduced the experimental data, in this case B3LYP/6-311++G**. The values of the descriptors obtained from the calculations with this level of theory were compared with those obtained from the high resolution X-ray diffraction experiments and resulted in good agreement in the description of the topology of the electronic charge density. The descriptors presented values are very close to those reported in the literature for the functional groups in the 5-FC and INH molecules. Images of the maps of the gradient trajectory and Laplacian of charge density, bond paths and atomic basins contours, allowed visualizing the regions of depletion and accumulation of charge density. Through these representations it was possible to describe the hydrogen bonds responsible for the stabilization of the cocrystal, the covalent chemical bonds and the deformations of the atomic basins that characterize the polarizations and the maps of the Laplacian that allow to observe the pairs of isolated electrons, such as those in fluorine, oxygen and nitrogen atoms.

Nesta tese de doutorado apresentamos os resultados de quatro tópicos referentes a estudos de propriedades elétricas que são interpretados com o auxílio da Teoria Quântica de Átomos em Moléculas (QTAIM). No primeiro deles, foram calculados momentos de dipolo e suas derivadas através de um novo formalismo de divisão de átomos em moléculas, baseado em campos de forças de Ehrenfest (CFE), sendo que estes dados são comparados com aqueles advindos da QTAIM. Desta forma, um modelo alternativo de partição em carga - fluxo de carga - fluxo de dipolo (CFCFD) é discutido para derivadas do momento dipolar. Os resultados gerais obtidos pelo formalismo CFE foram satisfatórios em termos quantitativos, embora QTAIM ainda fornece uma descrição mais apropriada destes fenômenos das polarizações atômicas e de suas variações durante vibrações. Na sequência, investigamos os Atratores Não Nucleares (NNAs), que são identificados através de uma análise QTAIM da densidade eletrônica. O nosso intuito foi descobrir novas moléculas que apresentam essa peculiaridade, bem como encontrar padrões entre os casos encontrados que permitam contribuir para o entendimento dos fatores que levam ao seu aparecimento. Para isso trabalhamos com moléculas diatômicas homonucleares de elementos representativos com números atômicos que variavam de Z=1 até Z=38 e moléculas heteronucleares formadas pela combinação dos mesmos. Os nossos dados mostram que NNAs podem ser encontrados em alguns pontos dentro da faixa de distâncias internucleares investigada para quase todos os sistemas diatômicos homonucleares, exceto para as moléculas de Hidrogênio, Hélio e Estrôncio. Por sua vez, encontramos trinta casos de NNAs em sistemas heteronucleares, muitos dos quais ainda inéditos na literatura. Descobrimos também que a polarizabilidade atômica aparentemente tem um papel importante na explicação dos casos encontrados. Tratamos também de moléculas contendo interações fracas como as de Van der Waals (moléculas tri-atômicas contendo um gás nobre ligado a um composto diatômico iônico) de modo a investigar os valores de dipolos atômicos QTAIM de uma maneira mais direta, ou seja, via comparação com um modelo simples para estes compostos. Por fim, estudamos moléculas em estados excitados, sendo que nossa análise focou em dois casos peculiares (CO e de CF2N2) que apresentam momento de dipolo nulo no estado fundamental, enquanto valores significativos desta propriedade são observados em seus primeiros estados excitados. Desta forma, QTAIM foi fundamental para compreender como o processo de excitação pode levar à mudanças tão significativas em tais propriedades elétricas. / In this PhD thesis we present the results of four different topics that refer to a study of electric properties interpreted with The Quantum Theory of Atoms and Molecules (QTAIM). First, dipole moments and their derivatives were calculated from a new formalism based on Ehrenfest Force Fields (EFF) and a comparison with data from QTAIM is carried out. Therefore, the Charge-Charge Flux-Dipole Flux (CCFDF) model was discussed for the dipole moment derivatives. The results from EFF were satisfactory in quantitative terms although QTAIM still seems to be better for the description of atomic polarization and its variations during vibrations. In the sequence, we investigated the Non-Nuclear Attractors (NNAs) that could be identified with the QTAIM formalism. Our intention was to discover new molecules that present this peculiarity, as well as to find trends among these cases that allow contributing for the understanding of the factors that lead to their appearance. For this purpose, we selected homonuclear diatomic molecules of elements presenting atomic numbers ranging from Z=1 to Z=38 and heteronuclear diatomic molecules containing these same elements. Our data shows that NNAs could be found in almost every homonuclear molecule expect by the systems formed by Hydrogen, Helium, and Strontium. On other hand, we have found 30 cases of NNAs in heteronuclear molecules, many of them seen for the first time. We also have noticed that the atomic polarizabilities play a main role in the understanding of these cases. We also treated molecules containing weak Van der Waals interactions (triatomic complexes presenting a noble gas bonded to a diatomic ionic molecule) in order to investigate the atomic dipole values obtained with QTAIM in a direct way, that is, by means of a comparison using a simple model for this kind of bonding. Finally, we studied molecules in excited states. Our focus was in two peculiar cases (CO and CF2N2), which present null dipole moments in their ground states but exhibit significant dipole moment values in their first excited states. Therefore, QTAIM was fundamental to understand how the excitation process can lead to important changes in electric properties.

En la literatura sobre mecànica quàntica és freqüent trobar descriptors basats en la densitat de parells o la densitat electrònica, amb un èxit divers segons les aplicacions que atenyin. Per tal de que tingui sentit químic un descriptor ha de donar la definició d'un àtom en una molècula, o ésser capaç d'identificar regions de l'espai molecular associades amb algun concepte químic (com pot ser un parell solitari o zona d'enllaç, entre d'altres). En aquesta línia, s'han proposat diversos esquemes de partició: la teoria d'àtoms en molècules (AIM), la funció de localització electrònica (ELF), les cel·les de Voroni, els àtoms de Hirshfeld, els àtoms difusos, etc.L'objectiu d'aquesta tesi és explorar descriptors de la densitat basats en particions de l'espai molecular del tipus AIM, ELF o àtoms difusos, analitzar els descriptors existents amb diferents nivells de teoria, proposar nous descriptors d'aromaticitat, així com estudiar l'habilitat de totes aquestes eines per discernir entre diferents mecanismes de reacció. / In the literature, several electronic descriptors based in the pair density or the density have been proposed with more or less success in their pratical applications. In order to be chemically meaningful the descriptor must give a definition of an "atom" in a molecule, or instead be able to identify some chemical interesting regions (such as lone pair, bonding region, among others). In this line, several molecular partition schemes have been put forward: atoms in molecules (AIM), electron localization function (ELF), Voronoi cells, Hirshfeld atoms, fuzzy atoms, etc. The goal of this thesis is to explore the density descriptors based on the molecular partitions of AIM, ELF and fuzzy atom, analyze the existing decriptors at several levels of theory, propose new aromaticity descriptors, and study its ability to discern between different mechanisms of reaction.

The thesis entitled “Addressing subtle physicochemical features exhibited by molecular crystals via Experimental and Theoretical Charge Density Analysis” consists of five chapters. An introductory note provides a brief description of experimental and theoretical charge density methodology, followed by its utilization in obtaining certain physical and chemical properties in molecular crystals. Chapter 1 addresses not so easily accessed molecular property arising due to electron conjugation, highlighting antiaromaticity in tetracyclones. A systematic study of six tetracyclone derivatives with electron withdrawing and electron donating substituents has been carried out using experimental and theoretical charge density analysis. A three pronged approach based on quantum theory of atoms in molecules (QTAIM), nucleus independent chemical shifts (NICS), and source function (SF) has been employed to establish the degree of antiaromaticity of the central five-membered ring in all the derivatives. Electrostatic potentials mapped on the is density surface reveal the finer effects of different electron withdrawing and electron donating substituents on the carbonyl group. Chapter 2 presents a temperature induced reversible first order single crystal to single crystal phase transition (Room temperature Orthorhombic, P22121 to low temperature Monoclinic, P21) in a  hybrid peptide, Boc-γ4(R)Val-Val-OH. The thermal behavior accompanying the phase transition of the dipeptide crystal was characterized by differential scanning calorimetry, visual changes in birefringence of the sample during heating and cooling cycles on a hot-stage microscope with polarized light. Variable-temperature unit cell check measurements from 300 to 100 K showed discontinuity in the volume and cell parameters near the transition temperature, supporting the first-order behavior. The reversible nature of the phase transition is traced to be due to an interplay between enthalpy and entropy. Chapter 3 brings out an unusual stabilizing interaction involving a cooperative -hole and ¬hole character in a short NCS···NCS bond. This chapter describes structural features of four isothiocyanate derivatives, FmocXCH2NCS; X=Leu, Ile, Val and Ala. Among these it is observed that only FmocLeuCH2NCS which crystallizes in a tetragonal space group, P41, (a=b=12.4405(5) Å; c= 13.4141(8) Å) transforms isomorphously to a low temperature form, P41, (a=b=17.4665(1) Å; c= 13.1291(1) Å). The characteristics of the phase transition have been monitored by Differential Scanning Calorimetry, variable temperature IR and temperature dependent unit cell measurements. The short NCS···NCS intermolecular interaction (3.296(1) Å) is analyzed based on detailed experimental charge density analysis which reveals the nature of this stabilizing interaction. Chapter 4 explains a comparative study of syn and anti conformations of carboxylic acids in peptides from both structural aspect and charge density features. Single crystal structures of four peptides having syn conformations [BocLeuγ4(R)Valγ4(R)ValOH, BocLeuγ4(R)ValLeuγ4(R)ValOH, Boc3(S)Leu3(S)LeuOH] and one with anti conformation, BocLeuγ4(R)ValValOH have been analyzed. Experimental charge density analysis has been carried out exclusively on BocLeuγ4(R)ValValOH having anti form, because of its rare occurrence in literature. However, low temperature datasets on the four peptides with syn conformations were collected and theoretical charge density analysis has been carried out on two of these compounds. Electrostatic potentials mapped on is density surface bring out a significant difference at the oxygen atoms of the carboxyl group in the two conformations. However, lone pair orientation of different types of Oxygen atoms in the two forms (urethane, amide, acid) doesn’t exclusively indicate the differences in the corresponding charge density features. Chapter 5 addresses the issue of how sensitive are the charge density features associated with amino acid residues when the backbone conformational angles are varied. Three model systems, 1, L-alanyl–L-alanyl–L-alanine dehydrate; 2, anhydrous L-alanyl–L-alanyl–L¬alanine and 3, cyclo-(D,L-Pro)2(L-Ala)4 monohydrate have been chosen for this evaluation. Compound 1 has ant parallel alignment of tripe tide strands, and compound 2 has parallel alignment. All the alanine residues in compound 1 and 2 are in the -sheet region of the Ramachandran plot, whereas, the four Alanine residues in the cyclic hex peptide 3 span different regions of the Ramachandran plot. Theoretical multipole modelling has been carried out in order to explore the plausibility of transferring multipole parameters across different regions of Ramachandran Plot. Appendix I contains a brief description of charge shift bonding in Ph-CH2-Se-Se-CH2-Ph, as determined based on both experimental and theoretical charge density analysis. Appendix II contains a reprint of a published article on “Conformation-Changing Aggregation in Hydroxyacetone: A Combined Low-Temperature FTIR, Jet, and Crystallographic Study”.

Nesta tese de doutorado apresentamos os resultados de quatro tópicos referentes a estudos de propriedades elétricas que são interpretados com o auxílio da Teoria Quântica de Átomos em Moléculas (QTAIM). No primeiro deles, foram calculados momentos de dipolo e suas derivadas através de um novo formalismo de divisão de átomos em moléculas, baseado em campos de forças de Ehrenfest (CFE), sendo que estes dados são comparados com aqueles advindos da QTAIM. Desta forma, um modelo alternativo de partição em carga - fluxo de carga - fluxo de dipolo (CFCFD) é discutido para derivadas do momento dipolar. Os resultados gerais obtidos pelo formalismo CFE foram satisfatórios em termos quantitativos, embora QTAIM ainda fornece uma descrição mais apropriada destes fenômenos das polarizações atômicas e de suas variações durante vibrações. Na sequência, investigamos os Atratores Não Nucleares (NNAs), que são identificados através de uma análise QTAIM da densidade eletrônica. O nosso intuito foi descobrir novas moléculas que apresentam essa peculiaridade, bem como encontrar padrões entre os casos encontrados que permitam contribuir para o entendimento dos fatores que levam ao seu aparecimento. Para isso trabalhamos com moléculas diatômicas homonucleares de elementos representativos com números atômicos que variavam de Z=1 até Z=38 e moléculas heteronucleares formadas pela combinação dos mesmos. Os nossos dados mostram que NNAs podem ser encontrados em alguns pontos dentro da faixa de distâncias internucleares investigada para quase todos os sistemas diatômicos homonucleares, exceto para as moléculas de Hidrogênio, Hélio e Estrôncio. Por sua vez, encontramos trinta casos de NNAs em sistemas heteronucleares, muitos dos quais ainda inéditos na literatura. Descobrimos também que a polarizabilidade atômica aparentemente tem um papel importante na explicação dos casos encontrados. Tratamos também de moléculas contendo interações fracas como as de Van der Waals (moléculas tri-atômicas contendo um gás nobre ligado a um composto diatômico iônico) de modo a investigar os valores de dipolos atômicos QTAIM de uma maneira mais direta, ou seja, via comparação com um modelo simples para estes compostos. Por fim, estudamos moléculas em estados excitados, sendo que nossa análise focou em dois casos peculiares (CO e de CF2N2) que apresentam momento de dipolo nulo no estado fundamental, enquanto valores significativos desta propriedade são observados em seus primeiros estados excitados. Desta forma, QTAIM foi fundamental para compreender como o processo de excitação pode levar à mudanças tão significativas em tais propriedades elétricas. / In this PhD thesis we present the results of four different topics that refer to a study of electric properties interpreted with The Quantum Theory of Atoms and Molecules (QTAIM). First, dipole moments and their derivatives were calculated from a new formalism based on Ehrenfest Force Fields (EFF) and a comparison with data from QTAIM is carried out. Therefore, the Charge-Charge Flux-Dipole Flux (CCFDF) model was discussed for the dipole moment derivatives. The results from EFF were satisfactory in quantitative terms although QTAIM still seems to be better for the description of atomic polarization and its variations during vibrations. In the sequence, we investigated the Non-Nuclear Attractors (NNAs) that could be identified with the QTAIM formalism. Our intention was to discover new molecules that present this peculiarity, as well as to find trends among these cases that allow contributing for the understanding of the factors that lead to their appearance. For this purpose, we selected homonuclear diatomic molecules of elements presenting atomic numbers ranging from Z=1 to Z=38 and heteronuclear diatomic molecules containing these same elements. Our data shows that NNAs could be found in almost every homonuclear molecule expect by the systems formed by Hydrogen, Helium, and Strontium. On other hand, we have found 30 cases of NNAs in heteronuclear molecules, many of them seen for the first time. We also have noticed that the atomic polarizabilities play a main role in the understanding of these cases. We also treated molecules containing weak Van der Waals interactions (triatomic complexes presenting a noble gas bonded to a diatomic ionic molecule) in order to investigate the atomic dipole values obtained with QTAIM in a direct way, that is, by means of a comparison using a simple model for this kind of bonding. Finally, we studied molecules in excited states. Our focus was in two peculiar cases (CO and CF2N2), which present null dipole moments in their ground states but exhibit significant dipole moment values in their first excited states. Therefore, QTAIM was fundamental to understand how the excitation process can lead to important changes in electric properties.

No description available.

Die Streuung niederenergetischer Ionen zur chemischen Analyse und Strukturbestimmung von Festkörperoberflächen gehört mittlerweile zu den Standardverfahren der Oberflächenphysik. Weniger bekannt ist sicherlich, daß die Ionenstreuung auch zur Untersuchung magnetischer Oberflächen eingesetzt werden kann. Diese Methode beruht auf dem Einfang spinpolarisierter Elektronen von einer Festkörperoberfläche und trägt daher den Namen Elektroneneinfangsspektroskopie (engl.: Electron Capture Spectroscopy, ECS). Das verwendete Verfahren zum (indirekten) Nachweis einer Spinpolarisation der Oberflächenelektronen basiert auf dem Effekt, daß ein geringer Teil der Ionen nach der Wechselwirkung mit der Oberfläche ein Elektron in einen angeregten Projektilzustand eingefangen hat. Die nachfolgende Abregung kann durch die Emission polarisierter Strahlung erfolgen. Der Grad der Zirkularpolarisation hängt unter anderem vom Magnetisierungszustand der Oberfläche ab. In dieser Arbeit wurden Experimente an drei verschiedenen Systemen durchgeführt. Als Projektile dienten dabei einfach geladene Heliumionen mit Primärenergien zwischen 2 und 14 keV, die unter verschiedenen Einfallswinkeln an der Probe gestreut wurden. Die Lichtemission eines Triplett-Übergangs im sichtbaren Spektralbereich (Wellenlänge: 587.6 nm) wurde im Experiment analysiert. Zunächst wurden ECS-Messungen an einer unmagnetischen Kupfer(111)-Oberfläche durchgeführt. Dabei konnte gezeigt werden, daß die Emission polarisierter Strahlung von verschiedenen experimentellen Parametern abhängt. Dazu gehört neben der Primärenergie der Projektilionen auch deren Einfallswinkel. Ein statisches Magnetfeld, das mit einem Weicheisenjoch erzeugt wird, hat keinen Einfluß auf die Lichtpolarisation bei einer unmagnetischen Probe. Die ECS-Messungen an einer amorphen ferromagnetischen Oberfläche ergaben, daß mit dieser Methode prinzipiell auch Ummagnetisierungskurven ferromagnetischer Festkörperoberflächen bestimmt werden können. Die im Vergleich zu den ebenfalls untersuchten MOKE-Hysteresen charakteristische, leicht abgerundetete Form der Kurven ist ein experimenteller Nachweis dafür, daß die Elektroneneinfangsspektroskopie eine extrem oberflächensensitive Meßmethode ist. Diese Oberflächenempfindlichkeit ist eine unmittelbare Konsequenz des Formierungsabstands des angeregten Heliumzustands. Die Messungen am System Co/Cu(111) konnten zeigen, daß die ECS-Methode prinzipiell auch bei dünnen ferromagnetischen Schichten anwendbar ist, die auf ein unmagnetisches Substratmaterial gedampft wurden. Hier ergaben sich u.a. interessante Abhängigkeiten des magnetischen Signals von der Dicke der aufgedampften Schicht, die sich erstaunlich gut mit den mikromorphologischen Eigenschaften des Kobaltfilms korrelieren ließen. Ferner wurde gezeigt, daß mit der ECS-Methode auch Hysteresen dünner ferromagnetischer Schichten gemessen werden können.

The presented work investigates planar and axial channeling effects in ion-surface collisions. Therefore, energy loss and charge state distributions depending on the crystalline surface direction are recorded and analyzed. Several additional scattering parameters, like the primary energy, the outgoing charge state, the scattering angle, and the angle of incidence are varied. Multi-peak structures in the energy spectra are observed under axial channeling conditions and attributed to different trajectory classes. Using combined trajectory and inelastic energy loss calculations we are able to unambiguously assign the different peaks in the energy spectra to the different types of trajectories found in the calculations. By this, we investigate the electronic density corrugation at different metal surfaces. Die vorliegende Arbeit untersucht den Einfluß von axialem und planarem Channeling auf den Energieverlust von oberflächengestreuten Ionen. Es werden Energieverlustspektren und Ladungsverteilungen in Abhängigkeit der Parameter Primärenergie, gestreuter Ladungszustand, Streuwinkel, Einfallswinkel und der azimuthalen Ausrichtung der Oberfläche gemessen. Im Fall von axialem Channeling beobachten wir in den Energiespektren eine Multi-Peak Struktur. Diese läßt sich auf unterschiedliche Teilchentrajektorien zurückführen. Zusammen mit theoretischen Berechnungen des inelastischen Energieverlustes kann eine eindeutige Zuordnung zwischen dem gemessenen Energieverlust und der dazugehörigen Trajektorienart gemacht werden. Diese Technik erlaubt es uns, die elektronische Dichtekorrugation an Oberflächen zu studieren.