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See detailEtude par Spectrométrie de Masse de la formation d'Ions Négatifs par Attachement Electronique Dissociatif et par le processus de Paire d'Ions.
Locht, Robert ULg

Doctoral thesis (1971)

The aim of this work is to investigate the appearance of negative ions by both the mechanism of Dissociative Electron Attachment (DEA) and Ion Pair processes (IPP) by electron impact. Using the ... [more ▼]

The aim of this work is to investigate the appearance of negative ions by both the mechanism of Dissociative Electron Attachment (DEA) and Ion Pair processes (IPP) by electron impact. Using the appropriate instrumentation (a conventional Nier type mass spectrometer) the best conditions are chosen to ensure ion-molecule collision free ion production (sample pressure, impinging electron beam current), the linearity of the electron energy scale between 2 eV and 100 eV and to minimize mass (and translational kinetic energy) discrimination. The used ionizing electron beam allowed us a resolution of 0.5 eV. An ionization model for both processes is proposed to provide us a method for the measurement of the threshold energy of DEA and IPP. Were necessary the numerical derivation of the ion current (for IPP) and the deconvolution of the ionization efficiency curves (for both DEA and IPP) are applied to increase the accuracy of the threshold energy determination and the resolution of the successive ion producing processes to be observed. DEA and IPP’s are observed and threshold energies are measured and assigned in: (i) diatomic molecules, i.e. H2, CO, NO and O2, (ii) triatomic molecules, i.e. CO2 and CS2 along the reaction paths providing O- and S- and CS-. No CO- ion has been detected. (iii) polyatomic molecules, i.e. CH4, C2H2, C2H4, C2H3F and C2H3Cl. Beside the monoatomic negative ions (H-, C-), diatomic and polyatomic negative ions are detected. For several of these species the electron affinity (EA) of the radical is not known, e.g. CH, C2 and C2H. From the appearance of the corresponding negative ions and threshold measurements this fundamental quantity has been deduced. In the particular case of C2-, the production of the negative ion in an electronically excited state has been put forward for the first time. Dissociation energies of the same diatomic and triatomic negative ions have been deduced and compared with this same magnitude in neutral and positive ionic species. [less ▲]

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See detailEtude par Spectrométrie de Masse des Mécanismes d'Apparition des Ions Négatifs dans le Méthane.
Locht, Robert ULg

in Extrait du Bulletin de la Société Royale des Sciences de Liège (1966), 35(11-12), 764-777

The negative fragment ions appearing in methane have been investigated using a sector field mass spectrometer. By recording the ionzation efficiency curves of each ion it has been possible to determine ... [more ▼]

The negative fragment ions appearing in methane have been investigated using a sector field mass spectrometer. By recording the ionzation efficiency curves of each ion it has been possible to determine the appearance potentials for several processes. Interpretations of the mechanisms for these critical potentials have been attempted. [less ▲]

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See detailEtude par spectrométrie de masse du comportement de complexes organométalliques lors de l'activation par collision
Collette, Caroline ULg

Master's dissertation (1995)

The study by mass spectrometry with electrospray ionization of organometallic complexes was performed in order to elucidate the mechanism of reduction of ions in the gas phase that occurs in the region of ... [more ▼]

The study by mass spectrometry with electrospray ionization of organometallic complexes was performed in order to elucidate the mechanism of reduction of ions in the gas phase that occurs in the region of the cone of the electrospray source. The prospects of this work are a better understanding of the mechanisms of fragmentation of ions in the gas phase in the area of the source and the opportunity to study the reactions of these complexes in the absence of solvent. [less ▲]

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See detailEtude par spectrométrie Mössbauer de la distribution du fer dans les fractions minéralogiques séparées de roches lunaires rapportées par Apollo 12
Duchesne, Jules; Depireux, Joseph ULg; Gérard, A. et al

in Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique. Sciences (1971), 5e série, v. 4(LVII), 1204-1211

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See detailEtude par spectroscopie de génération de la fréquence somme de l'interface méthanol-platine
Vidal, F.; Busson, B.; Six, C. et al

in J. Phys. IV France (2002), 12

La spectroscopie vibrationnelle non-linéaire par génération de la fréquence somme est une sonde particulièrement adaptée à l'étude des interfaces entre milieux denses. Cette technique a été appliquée à l ... [more ▼]

La spectroscopie vibrationnelle non-linéaire par génération de la fréquence somme est une sonde particulièrement adaptée à l'étude des interfaces entre milieux denses. Cette technique a été appliquée à l'étude de l'interface électrochimique monocristal de platine/solution acide de méthanol, système qui constitue un modèle de pile à combustible, dispositif où l'énergie chimique est directement convertie en énergie électrique. Les propriétés vibrationnelles dépendent fortement de l'orientation cristallographique de l'électrode de platine. [less ▲]

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See detailEtude paysagère de la commune de Clavier
Vauchel, Bernadette ULg

Book - Société Nationale Terrienne (1979)

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See detailEtude phytochimique de plantes d'intérêt cosmétique à Mayotte
Saive, Matthew ULg

Diverse speeche and writing (2014)

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See detailEtude phytosociologique de la fagne Wallonne et de la fagne de Cléfay (structure et évolution des associations végétales à sphaignes dans les Hautes-Fagnes de Belgique).
Streel, Maurice ULg

in Académie Royale des Sciences, des Lettres et des Beaux Arts de Belgique. Classe des Sciences. Mémoires. Collection in-4o (1959), XXXI(1), 104

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See detailEtude phytosociologique et biochimique de la tourbière de Weywertz. Etude de la tourbe.
Deuse, P; Ramaut, J; Streel, Maurice ULg

in Bulletin de la Société Royale des Sciences de Liège (1957), 26(6), 325-340

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See detailEtude phytosociologique et biochimique de la tourbière de Weywertz. Etude de la végétation
Deuse, P; Ramaut, J; Streel, Maurice ULg

in Bulletin de la Société Royale des Sciences de Liège (1957), 26(5), 253-276

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See detailEtude pilote : Case management intégré dans les hôpitaux belges.
de Froidmont, C.; Dejace, Alain ULg; Englebert, L. et al

Report (1999)

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See detailEtude pilote pour le developpement d'un registre de l'infarctus du myocarde en region liegeoise (Belgique)
Paul, I.; Bilge, A.; Bolly, F. et al

in Revue d'Epidémiologie et de Santé Publique (2001), 49(5), 423-9

BACKGROUND: In 1998, a permanent registry of myocardial infarction was developed in the Liege area (Belgium) to provide updated, exhaustive and validated data on the morbidity and mortality from ... [more ▼]

BACKGROUND: In 1998, a permanent registry of myocardial infarction was developed in the Liege area (Belgium) to provide updated, exhaustive and validated data on the morbidity and mortality from cardiovascular causes, to define the patients' profile, to identify myocardial infarction therapeutic strategies and to complete and make comparisons with data collected in other parts of the country through methodologically identical registers. METHODS: All acute coronary events lethal or non lethal among individuals from both genders aged from 25 to 69 years and living in the area were registered according to the methodology developed for the MONICA project (Multinational Monitoring of Trends and Determinants in Cardiovascular Diseases) of WHO. The three main selected data sources were: death certificates, general practitioners and cardiologists, hospitals. The events were categorised according to symptoms, cardiac enzymes, electrocardiogram, history of chronic ischaemic heart disease and necropsy findings. RESULTS: The coronary-event rates were 283/100,000 in men and 102/100,000 in women. The case fatality rate, 28 days after the onset of the symptoms, was 30.6% for men and 36.2% for women, and 77.5% of deaths occurred in the first 24 hours after the onset of the symptoms. CONCLUSION: The development of a myocardial infarction register at a regional level requires the involvement of all health professionals dealing with that pathology. Such register has valuable public health interests, providing exhaustive and validated data on the pathology and its evolution as well as useful information for improving therapeutic strategies and developing adapted preventive measures. [less ▲]

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See detailEtude pilote relative à l'évaluation du risque sismique pour la ville de Liège
Plumier, André ULg; Degée, Hervé ULg

in Actes des journées APS-AFPS 2008 (2009)

Detailed reference viewed: 78 (14 ULg)