Journal De Physique Lettres最新文献

{"title":"Ion-quadrupole effects in thermal energy ion-molecule collision rate constants","authors":"A. Kosmas","doi":"10.1051/JPHYSLET:019850046017079900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017079900","url":null,"abstract":"A simplified version of the Averaged Quadrupole Orientation (AQO) theory is attempted, by taking into account the adiabatic invariance approximation, to investigate the effect of the ion-quadrupolar molecule interaction on thermal energy reaction rate constant. The theory is formulated in terms of an orientation averaged potential energy function and predicts a significant increase in the capture rate constant over the Langevin value for molecules with large quadrupole moments and small polarizabilities. The results of the theory are compared to various experimental data and predictions of other theories Developpement d'une version simplifiee de la theorie de l'orientation quadripolaire moyenne, en considerant la methode de l'invariant adiabatique, pour etudier l'effet du potentiel d'interaction d'un ion avec une molecule quadripolaire sur la constante de vitesse de la reaction aux energies thermiques","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"22 1","pages":"799-804"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72714858","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":"Large scale instability of nonlinear standing waves","authors":"P. Coullet, S. Fauve, E. Tirapegui","doi":"10.1051/JPHYSLET:019850046017078700","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017078700","url":null,"abstract":"We present the nonlinear phase equations describing the stability of a time-periodic one-dimensional spatial pattern, that arises in a system which is invariant by space and time translations and space reflection symmetry. We show that a large scale oscillatory instability can occur, leading to a quasiperiodic temporal regime with two different spatial scales On etablit les equations aux derivees partielles non lineaires qui gouvernent la stabilite a grande echelle d'une structure cellulaire unidimensionnelle oscillante, apparaissant dans un systeme hors equilibre, invariant par translations d'espace et de temps, et par reflexion d'espace. Existence d'une instabilite oscillatoire, conduisant a un regime quasi periodique, possedant deux echelles spatiales distinctes","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"118 1","pages":"787-791"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74869783","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":"Mean-field theory for optimization problems","authors":"H. Orland","doi":"10.1051/JPHYSLET:019850046017076300","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017076300","url":null,"abstract":"A mean-field theory for optimization problems of the Travelling Salesman type, or of the Matching type, is presented. It involves an infinite set of order parameters which measure the lack of self-averageness of the system and its degree of freezing. We further conjecture that NP-completeness is associated with replica symmetry breaking Theorie de champ moyen pour les problemes d'optimisation du type «Voyageur de Commerce» ou problemes d'«appariement», a l'aide d'un ensemble infini de parametres d'ordre, qui mesurent l'absence d'automoyennage du systeme et donc son degre de gel. On conjecture que la NP-complexite est associee a la brisure de symetrie des repliques","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"34 1","pages":"763-770"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81124286","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":"A new torsion pendulum technique to measure the twist elastic constant of liquid crystals","authors":"S. Faetti, M. Gatti, V. Palleschi","doi":"10.1051/JPHYSLET:019850046018088100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046018088100","url":null,"abstract":"A new experimental method to measure the twist elastic constant of nematic liquid crystals is proposed. The method is based on a direct measurement of the torque which the nematic liquid crystal exerts on the surfaces when a magnetic field is applied. The reliability of this technique is tested by measuring the twist elastic constant of the nematic liquid crystal 4-n-pentyl-4'-cyanobiphenyl (5CB). The experimental results are compared with previous measurements performed by other authors Technique basee sur une mesure directe du couple exerce par le directeur sur les surfaces quand le nematique est soumis a un champ magnetique. Application a la mesure de K 22 du pentyl-4 cyano-4' biphenyle","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"67 1","pages":"881-886"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76315846","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 coloration properties of CaF2 : Na","authors":"J. Tijero, J. Casas-González","doi":"10.1051/JPHYSLET:019850046018086100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046018086100","url":null,"abstract":"We have investigated the dichroic properties and the existence of metastable excited states of several colour centres created by X-irradiation in CaF 2 :Na. According to our results absorption bands peaking at 600, 385 and 322 nm are associated to the same centre which behaves optically as orthorhombic. The lack of observation of a metastable state is in favour of the F 2A + model for this centre. On the other hand the band at 500 nm and another absorption at 322 nm are proved to belong to the same centre which behaves optically as tetragonal. A metastable excited state of this centre with lifetime of 0,83 s at 77 K has been detected. Two possible models are discussed for this centre Etude des proprietes dichroiques et de l'existence d'etats excites metastables de plusieurs centres colores crees par irradiation X","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"10 1","pages":"861-868"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81636649","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":"Fractal structure of the equilibrium crystal shape. II. Fractal dimensions","authors":"S. Burkov","doi":"10.1051/JPHYSLET:019850046017080500","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017080500","url":null,"abstract":"A crystal shape at T=0 is studied in the framework of the model of «bricks» attracting each other according to 1/rγ. It is shown that fractal dimensions of the Cantor sets of solitary edges and corners are γ/(γ−2) and 6/(γ−1), respectively Etude de la forme d'un cristal a T=0 dans un modele de briques s'attirant selon une loi en 1/rγ","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"29 1","pages":"805-810"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89674053","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":"Phase diagram of quasi-one-dimensional conductors in strong magnetic field","authors":"M. Héritier, G. Montambaux, P. Lederer","doi":"10.1051/JPHYSLET:019850046017083100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017083100","url":null,"abstract":"The phase diagram of quasi-1D conductors in magnetic field is derived. We perform a microscopic calculation of the Ginzburg-Landau free energy coefficients. They exhibit a novel behaviour as a function of field. As a result, different regimes of SDW ordering appear with increasing field, corresponding to different types of quantized nesting. This description may account for nearly all the available experimental data in (TMTSF) 2 ClO 4 Calcul microscopique des coefficients de Ginzburg-Landau pour l'energie libre, qui presentent un comportement original en fonction du champ magnetique: en champ croissant, apparition de differents regimes d'ordre d'onde de densite de spin correspondant a differents types de «nesting» quantifie. Explication de presque toutes les donnees experimentales sur (TMTSF) 2 ClO 4","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"20 1","pages":"831-836"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81417680","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":"THERMAL-CONDUCTIVITY AND THERMOELECTRIC-POWER OF UBE13","authors":"D. Jaccard, J. Flouquet, Z. Fisk, J. Smith, H. Ott","doi":"10.1051/JPHYSLET:019850046017081100","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017081100","url":null,"abstract":"J. Physique Lett. ler L-811 - L-817 SEPTEMBRE L-811 Classification Physics Abstracts 72.15E - 72.15J - 74.30E Thermal D. conductivity and thermoelectric UBe13 Jaccard, J. Flouquet Centre de Recherches France Z. power of Fisk, sur les Tres Basses Temperatures, CNRS, BP 166 X, 38042 Grenoble Cedex, J. L. Smith Materials Science and NM 87545, U.S.A. Technology Division, Los Alamos National Laboratory, Los Alamos, and H. R. Ott Laboratorium fur Festkorperphysik, CH-8093 Zurich, Switzerland Eidgenossische Technische Hochschule, Honggerberg, (Refu le 8 avril 1985, accepte sous forme definitive le 8 juillet 1985) Des mesures de resistivite, pouvoir thermoelectrique et de conductivite thermique du compose a fermions lourds UBe13 ainsi que leurs relations avec le diagramme de phase temperature- champ critique sont presentees. A basse temperature (T 1 K), le pouvoir thermoelectrique de la phase normale est gigantesque. La conductivite thermique suit une loi en T2 dans la phase supra- conductrice sans contribution lineaire en T contrairement a ce qui est observe dans UPt3. Resume. Measurements of the resistivity, thermoelectric power and thermal conductivity of the heavy fermion compound UBe13 and their relations to the temperature-upper critical field phase diagram are reported. At low temperature (T 1 K), enormous thermoelectric powers are detected in the normal phase. The thermal conductivity obeys a T2 law in the superconducting phase with no supplementary T contribution which is not observed in the other heavy fermion compound UPt3. Abstract 1. Introduction. The discovery of superconductivity in UBe 13 at T~ ~ 0.9 K [1] has revived the debate on the origin of the superconductivity in heavy fermion compounds first found in CeCu2 Si2 [2]. The heavy fermion character of UBel3 is proved by the large value of the ratio of the specific heat C to the temperature T near Tc : Cl T - 1 J/mole/K2 [3]. One of the peculiarities of UBe 13 is that the elec- tron mean free path is extremely short near T~. At 1 K, the electrical resistivity ( p ~ 190 Jl!} cm) [ 1-4] is almost that estimated for the unitary limit; no sign of Fermi liquid behaviour ( p ~ T 2) is detected By contrast with liquid 3 He for which the superfluid transition ( T~ ~ 2 mK) is far below the Fermi temperature TF [5], the definition of TF is not obvious. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyslet:019850046017081100","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"76 1","pages":"811-817"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76328759","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":"First-order CIC transition induced by Coulomb forces","authors":"S. Barǐsić, I. Barišić","doi":"10.1051/JPHYSLET:019850046017081900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017081900","url":null,"abstract":"It is shown that the long range Coulomb interaction between charged solitons is attractive. The transition from the commensurate to the incommensurate state occurs therefore at finite soliton density. Such transition is of the first order. The relevance of those results to real materials is briefly discussed Demonstration d'une interaction coulombienne attractive entre solitons charges, ce qui entraine une transformation commensurable→incommensurable du 1er ordre pour une densite de solitons finie","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"142 1","pages":"819-824"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80431072","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":"Parisi function q(x) for spin glasses near Tc","authors":"H. Sommers","doi":"10.1051/JPHYSLET:019850046017077900","DOIUrl":"https://doi.org/10.1051/JPHYSLET:019850046017077900","url":null,"abstract":"We compute the orderparameter function q(x) for the Sherrington-Kirkpatrick spin-glass to high accuracy near T=T c in zero external field. The free energy is calculated to order (T c −T) 7 . The overlap function dx/dq is parabolic near q=0. We show generally that q(x) involves only odd powers of x below its plateau. Hence the overlap distribution in strictly zero fields is symmetric with continuous derivatives at q=0 Calcul de la fonction parametre d'ordre q(x) pour un verre de spin de Sherrington-Kirkpatrick en champ nul pres de T c , l'energie libre etant developpee jusqu'a l'ordre (T c -T 7 ): la fonction de recouvrement dx/dq est parabolique au voisinage de q=0, et q(x) ne contient que des puissances impaires de x au-dessous de la region du plateau","PeriodicalId":14822,"journal":{"name":"Journal De Physique Lettres","volume":"17 1","pages":"779-785"},"PeriodicalIF":0.0,"publicationDate":"1985-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89394689","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}