Spectroscopy and metastability of CO 2 2+ molecular ions

The spectroscopy and metastability of the carbon dioxide doubly charged ion, the CO ₂ ²⁺ dication, have been studied with photoionization experiments: time-of-flight photoelectron photoelectron coincidence (TOF-PEPECO), threshold photoelectrons coincidence (TPEsCO), and threshold photoelectrons and ion coincidence (TPEsCO ion coincidence) spectroscopies. Vibrational structure is observed in TOF-PEPECO and TPEsCO spectra of the ground and first two excited states. The vibrational structure is dominated by the symmetric stretch except in the TPEsCO spectrum of the ground state where an antisymmetric stretch progression is observed. All three vibrational frequencies are deduced for the ground state and symmetric stretch and bending frequencies are deduced for the first two excited states. Some vibrational structure of higher electronic states is also observed. The threshold for double ionization of carbon dioxide is reported as 37.340±0.010 eV. The fragmentation of energy selected CO ₂ ²⁺ ions has been investigated with TPEsCO ion coincidence spectroscopy. A band of metastable states from ∼38.7 to ∼41 eV above the ground state of neutral CO ₂ has been observed in the experimental time window of ∼0.1-2.3 μs with a tendency towards shorter lifetimes at higher energies. It is proposed that the metastability is due to slow spin forbidden conversion from bound excited singlet states to unbound continuum states of the triplet ground state. Another result of this investigation is the observation of CO ⁺+O ⁺ formation in indirect dissociative double photoionization below the threshold for formation of CO ₂ ²⁺. The threshold for CO ⁺+O ⁺ formation is found to be 35.56±0.10 eV or lower, which is more than 2 eV lower than previous measurements.

Quand la manifestation tourne à l'émeute : les affrontements violents entre forces de l'ordre et manifestants en Côte d'Ivoire.

Les manifestations de crise, en Côte d'Ivoire, ont été extrêmement violentes. Au cours des quinze dernières années, plus de 400 personnes sont mortes, tuées dans des affrontements avec les forces de sécurités ou des contre-manifestants. Malgré la gravité du problème, peu d’études scientifiques y sont consacrées et les rares analyses et enquêtes existantes portent, de façon unilatérale, sur l’identité et la responsabilité pénale des auteurs et commanditaires putatifs de cette violence. La présente étude s’élève contre le moralisme inhérent à ces approches pour aborder la question sous l’angle de l’interaction : cette thèse a pour objectif de comprendre les processus et logiques qui sous-tendent l’usage de la violence au cours des manifestations. Le cadre théorique utilisé dans cette étude qualitative est l’interactionnisme symbolique. Le matériel d’analyse est composé d’entrevues et de divers documents. Trente-trois (33) entrevues semi-dirigées ont été réalisées avec des policiers et des manifestants, cooptés selon la technique de la boule de neige, entre le 3 janvier et le 15 mai 2013, à Abidjan. Les rapports d’enquête, de l’ONG Human Rights Watch, sur les manifestations de crise, les manuels de formation de la police et divers autres matériaux périphériques ont également été consultés. Les données ont été analysées suivant les principes et techniques de la théorisation ancrée (Paillée, 1994). Trois principaux résultats ont été obtenus. Premièrement, le système ivoirien de maintien de l'ordre est conçu selon le modèle d’une « police du prince ». Les forces de sécurité dans leur ensemble y occupent une fonction subalterne d’exécutant. Elles sont placées sous autorité politique avec pour mandat la défense inconditionnelle des institutions. Le style standard de gestion des foules, qui en découle, est légaliste et répressif, correspondant au style d’escalade de la force (McPhail, Schweingruber, & Carthy, 1998). Cette « police du prince » dispose toutefois de marges de manœuvre sur le terrain, qui lui permettent de moduler son style en fonction de la conception qu’elle se fait de l’attitude des manifestants : paternaliste avec les foules dites calmes, elle devient répressive ou déviante avec les foules qu’elle définit comme étant hostiles. Deuxièmement, à rebours d’une conception victimaire de la foule, la violence est une transaction situationnelle dynamique entre forces de sécurité et manifestants. La violence suit un processus ascendant dont les séquences et les règles d’enchainement sont décrites. Ainsi, le premier niveau auquel s’arrête la majorité des manifestations est celui d’une force non létale bilatérale dans lequel les deux acteurs, protestataires et policiers, ont recours à des armes non incapacitantes, où les cailloux des premiers répondent au gaz lacrymogène des seconds. Le deuxième niveau correspond à la létalité unilatérale : la police ouvre le feu lorsque les manifestants se rapprochent de trop près. Le troisième et dernier niveau est atteint lorsque les manifestants utilisent à leur tour des armes à feu, la létalité est alors bilatérale. Troisièmement, enfin, le concept de « l’indignité républicaine » rend compte de la logique de la violence dans les manifestations. La violence se déclenche et s’intensifie lorsqu’une des parties, manifestants ou policiers, interprète l’acte posé par l’adversaire comme étant en rupture avec le rôle attendu du statut qu’il revendique dans la manifestation. Cet acte jugé indigne a pour conséquence de le priver de la déférence rattachée à son statut et de justifier à son encontre l’usage de la force. Ces actes d’indignités, du point de vue des policiers, sont symbolisés par la figure du manifestant hostile. Pour les manifestants, l’indignité des forces de sécurité se reconnait par des actes qui les assimilent à une milice privée. Le degré d’indignité perçu de l’acte explique le niveau d’allocation de la violence.

Justice envers les enfants et légitimité politique en éducation

L’idée selon laquelle les enfants sont des sujets à part entière de considérations de justice n’est pas très contestée. Les enfants ont des intérêts qui leur sont propres et ont un statut moral indépendant de leurs parents : ils ne sont ni la propriété de ces derniers ni une simple extension de leur personne. Pourtant, les travaux des plus grands théoriciens de la justice en philosophie politique contemporaine ne contiennent pas de discussion systématique du statut moral et politique des enfants et du contenu de nos obligations à leur égard. Cette thèse contribue à remédier à cette omission à travers l’examen de quatre grandes questions principales. (1) Quelles sont les obligations de justice de l’état libéral envers les enfants ? (2) Quels types de politiques publiques en matière d’éducation des enfants sont moralement légitimes ? (3) Jusqu’à quel point est-il moralement acceptable pour les parents de délibérément forger la vision du monde de leurs enfants ? (4) Quels critères moraux devraient guider l’élaboration de politiques en matière d’éducation morale dans les écoles ? Cette thèse est constituée de quatre articles. Le premier, « Political Liberalism and Children’s Education », aborde les questions du fondement normatif et des implications du principe de ‘neutralité éducative’ ou ‘anti-perfectionnisme éducatif’. Selon ce principe, il n’est pas légitime pour l’État libéral de délibérément promouvoir, à travers ses politiques publiques en éducation, une conception particulière de la vie bonne. L’article défend les idées suivantes. D’abord, ledit principe est exclusivement fondé sur des raisons de justice envers les parents. Ensuite, l’anti-perfectionnisme libéral n’est pas, pour autant, ‘mauvais pour les enfants’, puisqu’une vaste gamme d’interventions politiques dans la vie familiale et l’éducation des enfants sont, de manière surprenante, justifiables dans ce cadre théorique. Le deuxième article, « On the Permissibility of Shaping Children’s Values », examine la question de savoir si les parents ont un droit moral de forger délibérément l’identité, la conception du monde et les valeurs de leurs enfants. L’article développe une critique de la conception anti-perfectionniste des devoirs parentaux et propose un nouvel argument libéral à l’appui d’un droit parental conditionnel de forger l’identité de leurs enfants. L’article introduit également une distinction importante entre les notions d’éducation compréhensive et d’« enrôlement » compréhensif. Le troisième article, « Common Education and the Practice of Liberal Neutrality: The Loyola High School Case », défend trois thèses principales à travers une analyse normative de l’affaire juridique de l’école Loyola. Premièrement, il est légitime pour l’État libéral d’adopter un modèle d’éducation commune fort. Deuxièmement, la thèse selon laquelle la neutralité comme approche éducative serait impossible est injustifiée. Troisièmement, il existe néanmoins de bonnes raisons pour l’État libéral d’accommoder plusieurs écoles religieuses qui rejettent le modèle de la neutralité. Le quatrième article, « Which Moral Issues Should be Taught as Controversial? », critique à la fois le critère ‘épistémique’ dominant pour déterminer quels enjeux moraux devraient être enseignés aux jeunes comme ‘controversés’, et à la fois la manière dont le débat sur l’enseignement des enjeux controversés fut construit au cours des dernières années, d’un point de vue substantiel et méthodologique. L’article propose une manière alternative d’aborder le débat, laquelle prend adéquatement en compte la pluralité des objectifs de l’éducation et un ensemble d’autres considérations morales pertinentes.

Iowa State Government Technology Assessment Project, 1995

The State of Iowa is conducting an as5essment of Information Technology (IT) in the Executive Branch. The purpose of this assessment is to gather data on costs, applications, systems, utilization, operations, hardware assets, administration and activities associated with the provision of IT services. To accomplish this, two leading technology vendors conducted an intense assessment. These vendors, Integrated System Solutions Corporation (ISSC), and Electronic Data Systems (EDS) analyzed extensive data provided by the various ·agencies and conducted on-site interviews during the week of November 13, 1995. Additionally, in the first week of December, the American Federation of State, County, and Municipal Employees (AFSCME) Iowa Council 61 sponsored an assessment. These assessments are included as appendices B, C, and D to this report.

Understanding near Fermi-level electronic structure through x-ray emission spectroscopy

Thesis (Ph.D.)--University of Washington, 2016-08

The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium.

The long-standing Acid Growth Theory of plant cell elongation posits that auxin promotes cell elongation by stimulating cell wall acidification and thus expansin action. To date, the paucity of pertinent genetic materials has precluded thorough analysis of the importance of this concept in roots. The recent isolation of mutants of the model grass species Brachypodium distachyon with dramatically enhanced root cell elongation due to increased cellular auxin levels has allowed us to address this question. We found that the primary transcriptomic effect associated with elevated steady state auxin concentration in elongating root cells is upregulation of cell wall remodeling factors, notably expansins, while plant hormone signaling pathways maintain remarkable homeostasis. These changes are specifically accompanied by reduced cell wall arabinogalactan complexity but not by increased proton excretion. On the contrary, we observed a tendency for decreased rather than increased proton extrusion from root elongation zones with higher cellular auxin levels. Moreover, similar to Brachypodium, root cell elongation is, in general, robustly buffered against external pH fluctuation in Arabidopsis thaliana However, forced acidification through artificial proton pump activation inhibits root cell elongation. Thus, the interplay between auxin, proton pump activation, and expansin action may be more flexible in roots than in shoots.

Universality of weakly bound dimers and Efimov trimers close to Li-Cs Feshbach resonances

We study the interspecies scattering properties of ultracold Li-Cs mixtures in their two energetically lowest spin channels in the magnetic field range between 800 and 1000 G. Close to two broad Feshbach resonances (FR) we create weakly bound LiCs dimers by radio-frequency association and measure the dependence of their binding energy on the external magnetic field strength. Based on the binding energies and complementary atom loss spectroscopy of three other Li-Cs s-wave FRs we construct precise molecular singlet and triplet electronic ground state potentials using a coupled-channels calculation. We extract the Li-Cs interspecies scattering length as a function of the external field and obtain almost a ten-fold improvement in the precision of the values for the pole positions and widths of the s-wave FRs as compared to our previous work (Pires et al 2014 Phys. Rev. Lett. 112 250404). We discuss implications on the Efimov scenario and the universal geometric scaling for LiCsCs trimers.

Mossbauer scattering studies with the isotopes Os186, Os188, Eu153 and Pr1410

U of I Only

Influence of applied uniaxial stress upon the ultraviolet absorption bands in KBr and KI

The influence of uniaxial stress upon three types of imperfections occurring in the alkali halide crystal lattice has been investigated. The imperfections are the interstitial atom, the interstitial ion, and the negative ion vacancy. The interstitial atom, or H center, is a paraelastic defect which assumes a preferential crystal orientation in the field of an external mechanical stress. From the results of the reorientation kinetics - studies, it was possible to show that H centers are not stable in the KBr crystal lattice above 2SoK. At temperatures higher than 2SoK, the H centers are transformed into two new paraelastic defects, H(ii) and H(iii), possessing the same optical absorption band as the H center but differing both from the H' center and from each other in their reorientation kinetics. A study of the wavelength dependence of the H, H(ii), and VI (Na+) centers s~owed the 'existence of three similar-polarized transitions for each of these defects. One of these transitions, located at 230 run for all of the defects studied, was determined to be too high in energy to be explained by the simple X2 - level scheme. In addition, a comparison of various properties of the four defects indicates that the last three can be described as perturbed H centers. Dichroism measurements, performed as a function of temperature and wavelengt, h on the 230-nm I band in KBr, showed this band to be a composite of a band at 234 nm due to the I center and a band at 230 nm attributed to the H center. The I center dichroism was isolated and was observed under various experimental conditions. The results of these observations are consistent with a body-centered model for the I center in which the I-center absorption band is attributed to the excitation of a p-like electron on the interstitial Br- ion. Similar measurements were also perfonned on the a band in KI. The a-band dichroism measurements were found to be consistent with an electronic transition from an s-like ground state to a p-like excited state, indicating that the a center is best described as a quasi-molecule.

Quiralidade, superfície de energia potencial e dinâmica de complexos envolvendo H2O2 + gases nobres

Tese (doutorado)—Universidade de Brasília, Instituto de Física, 2015.

Trapping phosphorus (III) into polyoxometalates: synthesis, characterisation and electronic behaviour study

The introduction of electronically-active heteroanions into polyoxometalates (POMs) is one of the emerging topics in this field. The novel clusters have shown unprecedented intramolecular electron-transfer features that can be directly mediated by the incorporated heteroanions. In this thesis, we will focus on the study of phosphite (HPO32-) as new non-traditional heteroanions, discover HPO32- templated nanostructures, investigate their electronic behaviours as well as understand the self-assembly process of HPO32--templated species. The thesis starts with incorporating HPO32- into POM cages. The feasibility of this work was illustrated by the successful trapping of HPO32- into a “Trojan Horse” type {W18O56} nanocage. The reactivity of embedded {HPO3} was fully studied, showing the cluster undergoes a structural rearrangement in solution whereby the {HPO3} moieties dimerise to form a weakly interacting (O3PH···HPO3) moiety. In the crystalline state a temperature-dependent intramolecular redox reaction and structural rearrangement occurs. This rearrangement appears to proceed via an intermediate containing two different templates, a pyramidal {HPO3} and a tetrahedral {PO4} moiety. {HPO3} templated POM cages were then vigorously expanded and led to the isolation of five either fully oxidised or mixed-valence clusters trapped with mono-, di-, or tri- {HPO3}. Interestingly, an intriguing 3D honeycomb-like host-guest structure was also synthesised. The porous framework was self-aggregated by a tri-phopshite anion templated {W21} cluster with a {VO4} templated Wells-Dawson type {W18} acting as a guest species within the hexagonal channels. Based on this work, we further extended the templating anions to two different redox-active heteroanions, and discovered a unique mixed-heteroatom templated system built by pairing redox-active {HPIIIO3} with {TeO3}, {SeO3} or {AsO3}. Two molecular systems were developed, ie. “Trojan Horse” type [W18O56(HPO3)0.8(SeO3)1.2(H2O)2]8- and cross-shaped [H4P4X4W64O224]32-/36-, where X=TeIV, SeIV, AsIII. In the case of {W18(HPO3)0.8(SeO3)1.2}, the compound is found to be a mixture of heteroleptic {W18(HPO3)(SeO3)} and homoleptic {W18(SeO3)2} and {W18(HPO3)2}, identified by single crystal x-ray diffraction, NMR as well as high resolution mass spectrometry. The cluster exhibited similar temperature-dependent electronic features to “Trojan Horse” type {W18(HPO3)2O56}. However, due to the intrinsic reactivity difference between {HPO3} and {SeO3}, the thermal treatment leads to the formation of an unusual species [W18O55(PO4)(SeO3)]5-, in which {HPO3} was fully oxidised to {PO4} within the cage, whereas and lone-pair-containing {SeO3} heteroanions were kept intact inside the shell. This finding is extremely interesting, as it demonstrated that multiple and independent intramolecular electronic performance can be achieved by the coexistence of distinct heteroatoms within a single molecule. On the other hand, the cross-shaped [H4P4X4W64O224]32-/36- were constructed by four {W15(HPO3)(XO3)} building units linked by four {WO6} octahedra. Each building unit traps two different heteroatoms. It is interesting to note that the mixed heteroatom species show self-sorting, with a highly selective positional preference. Smaller ionic sized {HPO3} are self-organised into the uncapped side of {W15} cavity, whereas closed side are occupied by larger heteroatoms, which is surprisingly opposed to steric hindrance. Density functional theory (DFT) calculations are currently underway to have a full understanding of the preference of heteroatom substitutions. This series of clusters is of great interest in terms of achieving single molecule-based heteroatom-dependent multiple levels of electron transfer. It has opened a new way to design and synthesise POMs with higher diversity of electrical states, which may lead to a new type of Q-bits for quantum computing. The third chapter is focused on developing polyoxotungstate building blocks templated by {HPO3}. A series of building blocks, {W15O48(HPO3)2}, {W9O30(HPO3)} {W12O40(HPO3)2} and hexagonal {W6O18(HPO3)} have been obtained. The first four building blocks have been reported with {SeO3} and/or {TeO3} heteroanions. This result demonstrates {HPO3} has a similar reactivity as {SeO3} and {TeO3}, therefore studying the self-assembly of {HPO3}-based building blocks would be helpful to have a general understanding of pyramidal heteroatom-based molecular systems. The hexagonal {W6O18(HPO3)} is observed for the first time in polyoxotungstates, showing some of reactivity difference between {HPO3} and {SeO3} and {TeO3}. Furthermore, inorganic salts and pH values have some directing influence on the formation and transformation of various building blocks, resulting in the discovery of a family of {HPO3}-based clusters with nuclearity ranging from {W29} to {W106}. High resolution mass spectrometry was also carried out to investigate the cluster solution behaviour and also gain information of building block speciation. It is found that some clusters experienced decomposition, which gives rise to potential building blocks accountable for the self-assembly.

Analysis and control of transient spectra using time-dependent density functional theory.

215 p.

Influence of alkylphosphonic acid grafting on the electronic and magnetic properties of La2/3Sr1/3MnO3 surfaces

Self-assembled monolayers (SAMs) are highly promising materials for molecular engineering of electronic and spintronics devices thanks to their surface functionalization properties. In this direction, alkylphosphonic acids have been used to functionalize the most common ferromagnetic electrode in organic spintronics: La2/3Sr1/3MnO3 (LSMO). However, a study on the influence of SAMs grafting on LSMO electronic and magnetic properties is still missing. In this letter, we probe the influence of alkylphosphonic acids-based SAMs on the electronic and magnetic properties of the LSMO surface using different spectroscopies. We observe by X-ray photoemission and X-ray absorption that the grafting of the molecules on the LSMO surface induces a reduction of the Mn oxidation state. Ultraviolet photoelectron spectroscopy measurements also show that the LSMO work function can be modified by surface dipoles opening the door to both tune the charge and spin injection efficiencies in organic devices such as organic light-emitting diodes.