Journal De Physique最新文献

{"title":"High resolution electron microscopy of liquid crystalline polymers","authors":"I. Voigt-martin, H. Krug, D. Dyck","doi":"10.1051/JPHYS:0199000510200234700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200234700","url":null,"abstract":"Les images de microscopie electronique a haute resolution des polymeres cristaux liquides calamitiques [CO−CH(R)−CO 2 −(CH 2 ) 6 −OPh−N:N−PhO−(CH 2 ) 6 −O] n (R=CH 2 −CH=CH 2 , (CH 2 ) 6 −O−Ph N=N−Ph−CN) et discotique poly (hexadecanedioate de triphenylene) sont simulees sur ordinateur et comparees avec les structures obtenues a partir des resultats experimentaux de diffraction electronique. Une theorie est developpee pour expliquer le bon accord observe","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"51 1","pages":"2347-2371"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87966752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear electronic transport in dense plasmas. I. Specific features of Boltzmann-Ziman formalism within the Lorentzian approximation","authors":"D. Léger, C. Deutsch","doi":"10.1051/JPHYS:0199000510190218700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190218700","url":null,"abstract":"This is the first paper in a series devoted to a systematic investigation of linear electronic transport properties in strongly coupled plasmas consisting of a multicomponent and classical ionic mixture embbedded in a highly degenerate electron jellium. The basic formalism rests upon suitable extensions of the Boltzmann-Ziman theory as explained in this work. It is hereafter specialized in a thorough investigation of thermoelectronic and mechanical transport coefficients. Validity conditions for the Lorentzian approximation are first carefully examined. High temperature and inelastic corrections are emphasized. Basic transport quantities are expressed under an analytic and compact form both in the elastic and i Cet article est le premier d'une serie consacree a l'etude systematique du transport electronique lineaire dans les plasmas denses fortement couples, comportant plusieurs especes ioniques classiques plongees dans un jellium electronique fortement degenere. Le formalisme retenu, specialise ici au cas des coefficients thermoelectroniques et du transport mecanique (viscosite), repose pour l'essentiel sur l'extension de la theorie de Boltzmann-Ziman, dans le cadre de l'approximation Lorentzienne. Les conditions de validite de cette derniere sont largement developpees, et l'accent mis sur les corrections de temperature finies et les corrections inelastiques. Les coefficients de transport sont exprimes analytiquement sous forme de quantites reduites, a la fois dans le cas elastique et inelastique, respectivement au moyen des solutions exactes et variationnelles de l'equation de transport. Ceci permet un calcul simplifie des corrections precedemment mentionnees, calcul qui sera detaille dans l'article II de cette serie. Finalement, nous demontrons la validite de la methode en reproduisant, dans les limites appropriees, les formules de Ziman et d'Edwards pour la resistivite, ainsi que d'autres resultats bien connus","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"17 1","pages":"2187-2203"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90758169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ground state of the Fermi gas on 2D lattices with a magnetic field","authors":"R. Rammal, J. Bellissard","doi":"10.1051/JPHYS:0199000510190215300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190215300","url":null,"abstract":"The energy of 2D Bloch electrons in a magnetic field is studied as a function of the filling fractions ν and the magnetic flux φ. Using a new semi-classical quantization method the total energy E(φ,ν) is calculated and shown to have an absolute minimum which corresponds to one flux quantum per particle. This optimal flux phenomenon is shown to occur under large conditions and for different lattices. An explicit cusp-like behavior of E vs. φ at fixed ν is found both for the absolute and for the relative minima of E. Furthermore, the ground state energy is shown to be a smooth function of ν. The implications of our results for the stabilization of Anyons and the flux states are discussed On etudie l'energie des electrons de Bloch sous champ magnetique en fonction du flux magnetique φ et du taux de remplissage ν. On calcule l'energie totale E (φ,ν) a l'aide d'une nouvelle methode de quantification semi-classique. Le minimum absolu est atteint pour un choix optimal d'un quantum de flux par particule. Ce phenomene se produit pour differents reseaux et sous des conditions assez generales. Pour ν fixe, l'energie est une ligne brisee en fonction de φ. Toutefois, l'energie du fondamental est une fonction reguliere de ν. Les implications de ces resultats pour la stabilisation des Anyons et les phases de flux sont discutees","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"19 1","pages":"2153-2165"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79123506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced membrane rigidity in charged lamellar phases","authors":"P. Higgs, J. Joanny","doi":"10.1051/JPHYS:0199000510200230700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200230700","url":null,"abstract":"Lamellar phases formed by amphiphilic molecules consist of a stack of alternating solvent layers and surfactant membranes. The stability of the structure is governed by the interactions between neighboring membranes mediated by the solvent layers, these interactions include the Van der Waals attractive forces, the hydration forces and the electrostatic forces. It was argued by Helfrich [1] that due to the very low surface tensions, the out-of-plane undulations of the membrane are important and induce a repulsion of entropic origin between membranes. The strength of the undulation repulsion is controlled by the bending elasticity of the membranes that is usually described, by the bending constants kc and kc for the mean and Gaussian curvatures.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"365 1","pages":"2307-2320"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76558464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the ferroelectric phase transition in (CH3)4 NCdBr 3 (TMCB)","authors":"G. Aguirre-Zamalloa, M. Couzi, N. Chanh, B. Gallois","doi":"10.1051/JPHYS:0199000510190213500","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190213500","url":null,"abstract":"The ferroelectric phase transition in (CH 3 ) 4 NCdBr 3 (TMCB) at ∼156 K is studied by X-ray diffraction measurements; it is shown that the space group of the paraelectric phase is P6 3 /m, with lattice parameters a, a, c, and that of the ferroelectric phase is P6 1 (or P6 5 ) with lattice parameters a, a, 3c. The transition is analyzed in the framework of the Landau theory. In particular, the observed symmetry change implies the presence of cubic invariants (first-order transition). A classical Landau type expansion of the free-energy, including coupling terms with the polarization vector components (improper ferroelectric) is able to account satisfactorily for the temperature dependence of the spontaneous polarization and dielectric susceptibilities which have been previously measured La transition de phase ferroelectrique de (CH 3 ) 4 NCdBr 3 (TMCB) a ∼156 K est etudiee par diffraction des rayons X; on montre que le groupe d'espace de la phase paraelectrique est P6 3 /m, avec des parametres de maille a, a, c, et que celui de la phase ferroelectrique est P6 1 (ou P6 5 ) avec pour parametres a, a, 3c. La transition est analysee a l'aide de la theorie de Landau. En particulier, le changement de symetrie observe implique l'existence d'invariants d'ordre trois (transition du premier ordre). Un developpement classique de l'energie libre de Landau, incluant les termes de couplage avec les composantes du vecteur polarisation (ferroelectrique impropre) rend compte d'une maniere satisfaisante de la dependance en temperature de la polarisation spontanee et des susceptibilites dielectriques, mesurees precedemment","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"54 1","pages":"2135-2141"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73895311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small-angle scattering features of lyotropic smectics A","authors":"F. Nallet, D. Roux, S. Milner","doi":"10.1051/JPHYS:0199000510200233300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200233300","url":null,"abstract":"2014 Small-angle neutron scattering experiments on dilute lyotropic smectics A have been performed on oriented samples. The structure factor of a two-component smectic A is derived theoretically, taking explicitly into account the anisotropic coupling between concentration and layer displacement fluctuations. The anisotropic small-angle signal and other characteristic features of the spectra, and their evolutions with dilution, are predicted. The differences between electrostatically and sterically stabilized dilute lamellar phases are emphasized. Experiments are consistently described by the theory. J. Phys. France 51 (1990) 2333-2346 15 OCTOBRE 1990, 1","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"73 1","pages":"2333-2346"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76040930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unusual behavior of water soluble polyelectrolyte macromolecules shown by QELS study: is it a property of hydrophobic backbones ?","authors":"H. Mattoussi","doi":"10.1051/JPHYS:0199000510200232100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200232100","url":null,"abstract":"Etude du polyelectrolyte (Ph−CHR−CH 2 ) n (R= + SC 4 H 8 ) en solution aqueuse. En l'absence de sel, on observe 2 modes de fluctuations, un mode cooperatif et un mode a longue distance, ce qui reflete une conformation allongee du polyelectrolyte. L'augmentation de la force ionique de la solution entraine une reduction de la conformation et un seul mode de fluctuation est observable. Le coefficient de diffusion mutuelle ne depend pas des concentrations nen polymere et en sel en raison des interactions hydrophobes","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"2008 1","pages":"2321-2332"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86231639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetic theory of microphase separation in block copolymers","authors":"E. Aero, S. Vakulenko, A. Vilesov","doi":"10.1051/JPHYS:0199000510190220500","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190220500","url":null,"abstract":"A semiphenomenological theory that has the advantage of taking into account nonlinear and nonlocal contributions in the free energy for microphase separation of block copolymers is proposed. A kinetic nonlinear equation defining the process of structure formation from a melt is obtained, and its analytical solution at the melt-structure transition temperature is examined. In this region, the structure formation proceeds in two stages. The first one is characterized by damping of all but stable Fourier-components of density distribution and the second, by stabilization of the amplitude of the distribution. Characteristic times of these processes are estimated. The applied approach allows a comparatively simple definition of lamellar, hexagonal and body-centered cubic structures near Ts. Equilibrium structures at T ~ Ts are described as well.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"28 1","pages":"2205-2226"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78738260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectrum of 2D Bloch electrons in a periodic magnetic field : algebraic approach","authors":"A. Barelli, J. Bellissard, R. Rammal","doi":"10.1051/JPHYS:0199000510190216700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190216700","url":null,"abstract":"Algebraic methods recently introduced for 2D Bloch electrons in a uniform magnetic field are extended to the case of periodic magnetic fields. Using a semiclassical approach, we investigate the case where the magnetic unit cell is commensurate with the lattice unit cell. In general and according to the values φ of the average flux through the magnetic unit cell, two distinct cases take place. The first one corresponds to finite values of φ, where the usual structure of Landau levels is recovered (non commutative case). In the second case where φ=0, a non trivial band structure is obtained (commutative case). Our results are illustrated by simple examples. In particular we show that, under certain conditions, the mechanism of stabilization of the Fermi sea by the gaps (with one quantum flux per fermion) holds in the general case of periodic magnetic fields Les methodes algebriques que l'on a introduites recemment pour l'etude des electrons de Bloch sous champ magnetique uniforme sont generalisees au cas des champs periodiques. En utilisant une approche semi-classique, on etudie le cas ou la maille magnetique uniforme sont generalisees au cas des champs periodiques. En utilisant une approche semi-classique, on etudie le cas ou la maille magnetique est commensurable avec celle du reseau. En general et selon la valeur φ du flux magnetique moyen a travers la cellule elementaire, deux cas distincts semblent se distinguer. Le premier cas est φ¬=0, ou la structure en niveaux de Landau est retrouvee (cas non commutatif). Dans le second cas φ=0, on obtient une structure de bandes non triviale (cas commutatif). Nos resultats sont illustres avec des exemples simples. En particulier on montre, sous certaines conditions, que le mecanisme de stabilisation de la mer de Fermi, avec un quantum de flux par fermion, se generalise au cas d'un champ magnetique periodique","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"22 1","pages":"2167-2185"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87213317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High resolution spectroscopy of the hydrogen atom - III. Wavelength comparison and Rydberg constant determination","authors":"J. Garreau, M. Allegrini, L. Julien, F. Biraben","doi":"10.1051/JPHYS:0199000510200229300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200229300","url":null,"abstract":"Résumé. - Cet article le d’une donnant une description détaillée de notre mesure récente de la constante de Rydberg. Nous y décrivons soigneusement la méthode de mesure des longueurs d’onde. Les longueurs d’onde des trois transitions A deux photons 2S-8D, 2S-10D et 2S-12D dans l’hydrogène et le deutérium sont comparées à celle d’un laser He-Ne stabilisé sur l’iode, laser qui est actuellement la meilleure référence dans le domaine optique. Cette comparaison est faite à l’aide d’un étalon Fabry-Perot de grande stabilité. Les déphasages à la réflexion sont pris en compte en changeant la longueur de cette cavité (\"méthode des miroirs virtuels\"). Pour mesurer le déphasage de Fresnel nous étudions la différence de fréquence entre le premier mode transverse et le mode fondamental de cette cavité. A partir des six longueurs d’onde mesurées, nous déduisons une nouvelle valeur de la constante de Rydberg R~ = 109737, la plus précise à l’heure actuelle. A partir des déplacements isotopiques entre l’hydrogène et le deutérium nous déduisons aussi une valeur pour le rapport de masse entre le proton et l’électron: mp/me Abstract. 2014 This paper is the last of a series giving a detailed description of our recent determi- nation of the Rydberg constant. Here we carefully describe the wavelength comparison procedure. The wavelengths of the three two-photon transitions 2S-8D, 2S-10D, and 2S-12D in hydrogen and deuterium are compared to that of an I2-stabilized He-Ne laser which is the present best reference in the optical domain. The key of this comparison is a high stability Fabry-Perot cavity etalon. The reflective phase shifts are taken into account by changing the length of this cavity (\"virtual mirrors method\"). In order to measure the Fresnel phase shift we study the frequency difference between the first transverse mode and the fundamental mode of the cavity. From the six measured wavelengths we deduce a new value for the Rydberg constant, R~ = 109737.315709(18) cm-1, currently the most precise one. The H-D isotopic shifts have been also measured and a value for the proton-to-electron mass ratio is deduced: mp/me = 1836.15259(24).","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"9 1","pages":"2293-2306"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81973206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}