Showing papers by "Aix-Marseille University published in 1978"
TL;DR: In this paper, the authors investigated the effect of hydrogen ion impact on a tungsten single crystal in a field electron microscope and determined the time of the protrusion growth to a given size by measuring the increase of the field electron current.
36 citations
TL;DR: In this article, X-ray synchrotron radiation topography has been used for recrystallization studies of grain growth in order to catch a sight of nucleation-growth transition and distinguishing structure differences between moving and stationary grain boundaries.
Abstract: New possibilities provided to recrystallization studies by X-ray synchrotron radiation topography are tested and a preliminary investigation is presented. Reerystallization experiments are carried out in front of the X-ray synchrotron beam and topographs are made to observe the grain growth process. Firstly, the potentialities of this new technique are discussed and compared to those of previous methods (electron microscopy, photoemission-electron microscopy …) then it is shown what it allows to reach: 1) visibility of growth defect formation, 2) visibility of growth defect evolution, 3) catching a sight of nucleation-growth transition, 4) perhaps distinguishing structure differences between moving and stationary grain boundaries.
Neue Moglichkeiten, die fur Rekristallisationsuntersuchungen mittels Rontgen-Synchrotronstrahlungs-Topographie geeignet sind, werden getestet und eine vorlaufige Untersuchung mitgeteilt. Rekristallisationexperimente werden vor dem Rontgensynchrotronstrahl durchgefuhrt und Topographien fur die Beobachtung der Kornwachstumsprozesse hergestellt. Es werden die potentiellen Moglichkeiten dieser neuen Technik diskutiert und mit denen fruherer Methoden (Elektronenmikroskopie, Photoemissions-Elektronenmikroskopie …) verglichen, und es wird gezeigt, was sie zu erreichen ermoglicht: 1) Sichtbarmachung von Wachstumsdefektbildung, 2) Sichtbarmachung der Entwicklung der Wachstumsdefekte, 3) Darstellung von Keimbildungs-Wachstums-Ubergangen, 4) Unterscheidung von Strukturdifferenzen zwischen sich bewegenden und stationaren Korngrenzen.
34 citations
32 citations
TL;DR: The Late Precambrian or "Eocambrian" and the lowermost part of Palaeozoic rocks of West Africa and of the Western half of Central Africa include two lithostratigraphic sequences of sediments which we can identify as well on the craton as in the orogenic belts as discussed by the authors.
Abstract: The Late Precambrian or “Eocambrian” and the lowermost part of Palaeozoic rocks of West Africa and of the Western half of Central Africa include two lithostratigraphic sequences of sediments which we can identify as well on the craton as in the orogenic belts. The lower sequence, argillaceous, green colour, sometimes flyschoid, begins with a tillite or a mixtite. The upper sequence made of reddish, mainly continental sandstones, represents in some areas the molasse of the Pan-African Fold Belt.
28 citations
TL;DR: In this paper, a new method of generation of N-acyl-Nalkyl nitroxide radicals by photolysis of Nnitrosoamides is described, which shows a preferred trans conformation around the CON bond and hindered rotation around the NR′ σ-bond.
Abstract: A new method of generation of N-acyl-N-alkyl nitroxide radicals by photolysis of N-nitrosoamides is described. ESR parameters are reported for 17 radicals of the general formula RCON(R′)O.; the high resolution obtained allows conformational analysis which shows a preferred trans conformation around the CON bond and hindered rotation around the NR′ σ-bond.
14 citations
TL;DR: In this paper, an adaptation from a lecture at the Festkolloquium for Professor Muller's 65th birthday at the Fritz-Haber-Institut in West Berlin is presented.
14 citations
TL;DR: In this article, a model for the adsorption of n -alkane molecules on the (001) face of monoclinic even n-alkane crystals is proposed.
13 citations
TL;DR: In this article, the reaction entre thiolates de sodium and halogenures benzyliques donne lieu a la formation de radicaux libres, donné a la RPE grâce a la methode de piegeage.
9 citations
TL;DR: In this article, a model is built to describe the cellular growth of a dilute binary alloy, assuming a steady state shape of the solid-melt interface and using an extrenum principle of irreversible thermodynamics, the cellular size is calculated as a function of the parameters of growth.
5 citations
TL;DR: In this paper, experimental studies of quasi-elastic light scattering by semi-dilute solutions of polyadenilic acid showed the simultaneous existence of rapid modes similar to those observed with flexible chains, and slow modes the existence of which is due to polynucleotide chain dynamics.
Abstract: 2014 Our experimental studies of quasi-elastic light scattering by semi-dilute solutions of polyadenilic acid show the simultaneous existence of rapid modes similar to those observed with flexible chains, and of slow modes the existence of which is due to polynucleotide chain dynamics. The concentration dependence of diffusion coefficients gives some indications about the origin of these modes. LE JOURNAL DE PHYSIQUE LETTRES TOME 39, 1 er MAI 1978, F
4 citations
TL;DR: In this paper, the problem of growing high perfection crystals of dilute binary alloys with very low stacking fault energy has been considered, with Silver being chosen as the solvent, the choice of the solute is discussed and Ag-Sn crystals with increasing atomic concentrations of Sn from 0 to 6% have been grown.
TL;DR: In this article, the authors developed a program on high power, high efficiency, electronic lasers with particular focus on long pulse or possible c.w. emission of rare gases with molecular gas impurity.
TL;DR: This paper is an attempt to determine, among different file organizations, the one which requires the least cost, for every type of file organization.
TL;DR: In this article, the optical conductivity of europium was studied between 1.6 and 6.2 eV under static ultrahigh vacuum and it was shown that the total conductivity σ(ω) results from a coupling between frequency-dependent intraband, interband and structure terms.