Pub Date : 1990-10-01DOI: 10.1051/JPHYS:0199000510200226300
J. Garreau, M. Allegrini, L. Julien, F. Biraben
In order to determine the Rydberg constant R∞ to a very high accuracy, we have performed a Doppler-free two-photon absorption experiment on atomic hydrogen and deuterium. We have obtained a new value of R∞ which is in excellent agreement with other recent measurements and the most precise one at the present time. Here we give a detailed report on the method and apparatus we have used. A metastable beam of 2S H and D atoms has been prepared and laser excited to Rydberg nS and nD levels (n≽8) in a two-photon transition. The experimental geometry has been carefully designed to make the atomic beam collinear with the two counterpropagating laser beams. With this set-up we have observed very narrow resonances, with relative linewidths smaller than 10-9. Among all the transitions investigated we have selected three transitions (2S-8D, 2S-10D and 2S-12D) in hydrogen and deuterium to determine R ∞.
{"title":"High Resolution Spectroscopy of the Hydrogen Atom. I. Method and Experiment","authors":"J. Garreau, M. Allegrini, L. Julien, F. Biraben","doi":"10.1051/JPHYS:0199000510200226300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200226300","url":null,"abstract":"In order to determine the Rydberg constant R∞ to a very high accuracy, we have performed a Doppler-free two-photon absorption experiment on atomic hydrogen and deuterium. We have obtained a new value of R∞ which is in excellent agreement with other recent measurements and the most precise one at the present time. Here we give a detailed report on the method and apparatus we have used. A metastable beam of 2S H and D atoms has been prepared and laser excited to Rydberg nS and nD levels (n≽8) in a two-photon transition. The experimental geometry has been carefully designed to make the atomic beam collinear with the two counterpropagating laser beams. With this set-up we have observed very narrow resonances, with relative linewidths smaller than 10-9. Among all the transitions investigated we have selected three transitions (2S-8D, 2S-10D and 2S-12D) in hydrogen and deuterium to determine R ∞.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"79 1","pages":"2263-2273"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85378254","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}
Pub Date : 1990-10-01DOI: 10.1051/JPHYS:0199000510190214300
Y. Marathe, S. Ramaswamy
We have studied the hydrodynamics of freely suspended membranes, liquid as well as crystalline, with surface tension. We find that nonlinear coupling to thermally excited undulations gives a singular contribution to the kinetic coefficients of these systems at low frequency and wavenumber. Our results differ in some important respects from those of Katz and Lebedev on this problem, and can be tested in mechanical impedance as well as time-correlation studies.
{"title":"Dynamics of freely suspended films with surface tension","authors":"Y. Marathe, S. Ramaswamy","doi":"10.1051/JPHYS:0199000510190214300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510190214300","url":null,"abstract":"We have studied the hydrodynamics of freely suspended membranes, liquid as well as crystalline, with surface tension. We find that nonlinear coupling to thermally excited undulations gives a singular contribution to the kinetic coefficients of these systems at low frequency and wavenumber. Our results differ in some important respects from those of Katz and Lebedev on this problem, and can be tested in mechanical impedance as well as time-correlation studies.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"56 1","pages":"2143-2152"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82889585","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}
Pub Date : 1990-10-01DOI: 10.1051/JPHYS:0199000510200224300
P. Hello, J. Vinet
We study the aberrations of massive mirrors heated by partial of intense laser beams in the coating or in the bulk. The non-uniform temperature field generated in the solid substrate induce thermoelastic deformations for which with the special assumption of axial symmetry, we give analytical models and numerical evaluations, first in the steady state, then in the transient regime Nous nous interessons aux aberrations causees aux miroirs massifs par des faisceaux laser intenses echauffant les couches reflechissantes ou la masse meme du substrat. La distribution de temperature engendree dans le substrat produit des deformations thermoelastiques dont nous donnons des modeles analytiques et des evaluations numeriques dans le cas particulier de la symetrie axiale, tout d'abord dans l'etat stationnaire, puis dans le regime transitoire
{"title":"Analytical models of transient thermoelastic deformations of mirrors heated by high power cw laser beams","authors":"P. Hello, J. Vinet","doi":"10.1051/JPHYS:0199000510200224300","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200224300","url":null,"abstract":"We study the aberrations of massive mirrors heated by partial of intense laser beams in the coating or in the bulk. The non-uniform temperature field generated in the solid substrate induce thermoelastic deformations for which with the special assumption of axial symmetry, we give analytical models and numerical evaluations, first in the steady state, then in the transient regime Nous nous interessons aux aberrations causees aux miroirs massifs par des faisceaux laser intenses echauffant les couches reflechissantes ou la masse meme du substrat. La distribution de temperature engendree dans le substrat produit des deformations thermoelastiques dont nous donnons des modeles analytiques et des evaluations numeriques dans le cas particulier de la symetrie axiale, tout d'abord dans l'etat stationnaire, puis dans le regime transitoire","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"25 1","pages":"2243-2261"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82054476","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}
Pub Date : 1990-10-01DOI: 10.1051/JPHYS:0199000510200227500
J. Garreau, M. Allegrini, L. Julien, F. Biraben
Calcul theorique des formes de raies attendues dans l'experience de spectroscopie a deux photons des transitions 2S-ns' et 2S-nD de l'atome d'hydrogene. Calcul de la probabilite de transition a deux photons. Comparaison des profils experimentaux et theoriques
{"title":"High resolution spectroscopy of the hydrogen atom. II, Study of line profiles","authors":"J. Garreau, M. Allegrini, L. Julien, F. Biraben","doi":"10.1051/JPHYS:0199000510200227500","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510200227500","url":null,"abstract":"Calcul theorique des formes de raies attendues dans l'experience de spectroscopie a deux photons des transitions 2S-ns' et 2S-nD de l'atome d'hydrogene. Calcul de la probabilite de transition a deux photons. Comparaison des profils experimentaux et theoriques","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"268 1","pages":"2275-2292"},"PeriodicalIF":0.0,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77169301","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510170192900
P. Zeppenfeld, M. Bienfait, Feng Liu, O. Vilches, G. Coddens
Quasi-elastic neutron scattering has been used to measure, below the bulk melting temperature, the thickness and the diffusion coefficient of the mobile surface layer of 8 and 10 layer thick films of deuterium hydride (HD) condensed on MgO(100). The measurements show that the close-packed surface of solid HD surface melts gradually, with the thickness of the melted layer increasing from 0.5 to 6 molecular layers as the temperature rises from 4 K to 0.05 K below the bulk melting temperature. The diffusion coefficients are in the 10 −5 cm 2 s −1 range indicating that the surface disordered film is liquid-like Nous avons utilise la diffusion quasi-elastique de neutrons pour mesurer, en dessous de la temperature de fusion, l'epaisseur et le coefficient de diffusion de la couche mobile de surface de films d'epaisseur 8 et 10 couches moleculaires d'hydrure de deuterium (HD) condenses sur MgO(100). Les mesures montrent que la surface compacte de HD solide subit une prefusion avec une epaisseur de la couche fondue variant de 0.5 a 6 couches moleculaires dans le domaine de temperatures s'etendant de 4 K a 0.05 K en dessous du point de fusion (16.604 K). Les coefficients de diffusion tombent dans le domaine des 10 −5 cm 2 s −1 , ce qui indique que la couche de surface desordonnee se comporte comme un liquide
采用准弹性中子散射法测量了在体积熔化温度以下MgO(100)上凝聚的8层和10层厚氢化氘(HD)薄膜的可移动面层厚度和扩散系数。测量结果表明，固体HD表面密实堆积表面逐渐熔化，随着温度从低于体熔化温度的4 K升高到0.05 K，熔化层的厚度从0.5增加到6个分子层。扩散系数在10 ~ 5 cm ~ 2 s ~ 1范围内，表明表面无序膜是液体状的。Nous avons利用la扩散准弹性中子流测量仪，通过la温度熔合，l'epaisseur和l'扩散系数la couche移动，d'epaisseur 8和10 couche分子水氘(HD)凝结在MgO(100)上。Les测量了在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体，在1次预熔合条件下表面致密化的HD固体
{"title":"Surface melting of deuterium hydride thick films","authors":"P. Zeppenfeld, M. Bienfait, Feng Liu, O. Vilches, G. Coddens","doi":"10.1051/JPHYS:0199000510170192900","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510170192900","url":null,"abstract":"Quasi-elastic neutron scattering has been used to measure, below the bulk melting temperature, the thickness and the diffusion coefficient of the mobile surface layer of 8 and 10 layer thick films of deuterium hydride (HD) condensed on MgO(100). The measurements show that the close-packed surface of solid HD surface melts gradually, with the thickness of the melted layer increasing from 0.5 to 6 molecular layers as the temperature rises from 4 K to 0.05 K below the bulk melting temperature. The diffusion coefficients are in the 10 −5 cm 2 s −1 range indicating that the surface disordered film is liquid-like Nous avons utilise la diffusion quasi-elastique de neutrons pour mesurer, en dessous de la temperature de fusion, l'epaisseur et le coefficient de diffusion de la couche mobile de surface de films d'epaisseur 8 et 10 couches moleculaires d'hydrure de deuterium (HD) condenses sur MgO(100). Les mesures montrent que la surface compacte de HD solide subit une prefusion avec une epaisseur de la couche fondue variant de 0.5 a 6 couches moleculaires dans le domaine de temperatures s'etendant de 4 K a 0.05 K en dessous du point de fusion (16.604 K). Les coefficients de diffusion tombent dans le domaine des 10 −5 cm 2 s −1 , ce qui indique que la couche de surface desordonnee se comporte comme un liquide","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"23 1","pages":"1929-1938"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84341187","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510180205100
M. Pinard, M. Vallet, G. Grynberg
We present a theoretical and experimental study of the steady-state regime of a ring four-wave mixing oscillator. We study here the properties of the quasi-degenerate mode. The theory is developped using the Lamb equations. We show that the four-wave mixing oscillator can be used as a gyrometer and that its scale factor is identical to the gyrolaser scale factor. We calculate the lock-in band, which is due to backscattering on the mirrors, and show that an intrinsic non-linearity can be used to circumvent this problem by optical means only. Finally we describe the experiments we have performed using sodium vapor to observe these gyrometric properties Nous etudions les proprietes d'un oscillateur en anneau utilisant le melange a quatre ondes dans une vapeur atomique comme processus de gain. Notre etude concerne ici le mode de fonctionnement quasi degenere. L'etude theorique est faite au moyen des equations de Lamb. Nous montrons que le systeme se comporte comme un gyrometre et que son facteur d'echelle est identique a celui des gyrolasers. Nous calculons la zone aveugle de ce gyrometre, zone aveugle qui est due a la retrodiffusion sur les miroirs. Nous montrons aussi que l'utilisation d'une nonlinearite intrinseque permet de s'affranchir du probleme de la zone aveugle par un moyen purement optique. Finalement nous decrivons les experiences faites en utilisant une vapeur de sodium qui nous ont permis de mettre en evidence ces proprietes gyrometriques
本文对环形四波混频振荡器的稳态状态进行了理论和实验研究。本文研究了准简并模态的性质。这个理论是用兰姆方程发展起来的。我们证明了四波混频振荡器可以用作陀螺仪，并且它的尺度因子与陀螺激光器的尺度因子相同。我们计算了由于反射镜上的后向散射引起的锁相带，并表明仅通过光学手段就可以利用本征非线性来规避这一问题。最后，我们描述了我们用钠蒸气来观察这些陀螺特性的实验。我们的实验表明，我们的实验是用钠蒸气来观察这些陀螺特性的，我们的实验是用钠蒸气来观察这些陀螺特性的。本文研究了一类准退化模态函数。兰姆方程的理论是最基本的。我们的系统是由陀螺组成的，我们的系统是由陀螺组成的，我们的系统是由陀螺组成的，我们是由陀螺组成的。现在的计算方法是用区域平均速度测量陀螺仪，区域平均速度测试是用反射镜进行的。Nous monmonons aussi ' l l' utilization d'une非线性内部序列许可' s'affranchir ' problem de la zone average par on the optical。最后一种方法描述了一种实用的方法，一种方法描述了一种方法，一种方法描述了一种方法，一种方法描述了一种方法，一种方法描述了一种方法
{"title":"Etude théorique et expérimentale des propriétés gyrométriques d'un oscillateur à mélange à quatre ondes en anneau","authors":"M. Pinard, M. Vallet, G. Grynberg","doi":"10.1051/JPHYS:0199000510180205100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510180205100","url":null,"abstract":"We present a theoretical and experimental study of the steady-state regime of a ring four-wave mixing oscillator. We study here the properties of the quasi-degenerate mode. The theory is developped using the Lamb equations. We show that the four-wave mixing oscillator can be used as a gyrometer and that its scale factor is identical to the gyrolaser scale factor. We calculate the lock-in band, which is due to backscattering on the mirrors, and show that an intrinsic non-linearity can be used to circumvent this problem by optical means only. Finally we describe the experiments we have performed using sodium vapor to observe these gyrometric properties Nous etudions les proprietes d'un oscillateur en anneau utilisant le melange a quatre ondes dans une vapeur atomique comme processus de gain. Notre etude concerne ici le mode de fonctionnement quasi degenere. L'etude theorique est faite au moyen des equations de Lamb. Nous montrons que le systeme se comporte comme un gyrometre et que son facteur d'echelle est identique a celui des gyrolasers. Nous calculons la zone aveugle de ce gyrometre, zone aveugle qui est due a la retrodiffusion sur les miroirs. Nous montrons aussi que l'utilisation d'une nonlinearite intrinseque permet de s'affranchir du probleme de la zone aveugle par un moyen purement optique. Finalement nous decrivons les experiences faites en utilisant une vapeur de sodium qui nous ont permis de mettre en evidence ces proprietes gyrometriques","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"38 1","pages":"2051-2072"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89600532","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510170197900
S. Pelaud, P. Mazot, J. Woirgard
Internal friction measurements and complex impedance experiments have been performed on single crystal specimens of cubic stabilized zirconia. The frequency spectra observed for different temperatures, by internal friction and dielectric loss, give similar activation energies (1.29 and 1.26 eV), while the value obtained by D.C. conductivity is lightly higher (1.34 eV). Thus, it can be assumed that the oxygen jumps induced by mechanical or electrical sollicitation are very probably the same; the relaxation times deduced from the two sollicitation modes are effectively in a 3 ratio, in a good agreement with Nowick's theoretical approach L'etude en frequence des spectres obtenus a differentes temperatures en frottement interieur et en pertes dielectriques permet la mise en evidence, par les deux methodes, d'energies d'activation tres similaires (1,29 et 1,26 eV), l'energie obtenue pour la conductivite en courant continu etant legerement superieure (1,34 eV). On peut conclure que les mecanismes de saut de l'oxygene induits sous contrainte mecanique ou electrique sont tres vraisemblablement identiques; les temps de relaxation limites mesures par les deux methodes sont en effet dans un rapport de l'ordre de 3 proche des previsions theoriques de Nowick
对立方稳定氧化锆单晶试样进行了内摩擦测量和复杂阻抗实验。通过内摩擦和介电损耗观察到的不同温度下的频谱得到相似的活化能(1.29和1.26 eV)，而通过直流电导率得到的活化能略高(1.34 eV)。因此，可以假定由机械或电诱导引起的氧跳很可能是相同的;的松弛时间推断两种sollicitation模式有效地在一个3比,在良好的协议与Nowick理论的方法我在频数des幽灵obtenus温度不同的en frottement interieur et en pert dielectriques允许必要的证据,两者方法,d 'energies d 'activation非常similaires(1, 29日et 1, 26 eV), L 'energie obtenue pour la conductivite en柯朗继续etant legerement师范学院(1,34 eV)。关于氧诱导的机理、电诱导的机理和电诱导的机理的研究;温度、弛豫、极限、测量、两种方法、效应、关系、顺序、过程、诺威克理论
{"title":"Etude par frottement intrieur et impdance complexe d'une zircone calcie cubique ZrO2-CaO","authors":"S. Pelaud, P. Mazot, J. Woirgard","doi":"10.1051/JPHYS:0199000510170197900","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510170197900","url":null,"abstract":"Internal friction measurements and complex impedance experiments have been performed on single crystal specimens of cubic stabilized zirconia. The frequency spectra observed for different temperatures, by internal friction and dielectric loss, give similar activation energies (1.29 and 1.26 eV), while the value obtained by D.C. conductivity is lightly higher (1.34 eV). Thus, it can be assumed that the oxygen jumps induced by mechanical or electrical sollicitation are very probably the same; the relaxation times deduced from the two sollicitation modes are effectively in a 3 ratio, in a good agreement with Nowick's theoretical approach L'etude en frequence des spectres obtenus a differentes temperatures en frottement interieur et en pertes dielectriques permet la mise en evidence, par les deux methodes, d'energies d'activation tres similaires (1,29 et 1,26 eV), l'energie obtenue pour la conductivite en courant continu etant legerement superieure (1,34 eV). On peut conclure que les mecanismes de saut de l'oxygene induits sous contrainte mecanique ou electrique sont tres vraisemblablement identiques; les temps de relaxation limites mesures par les deux methodes sont en effet dans un rapport de l'ordre de 3 proche des previsions theoriques de Nowick","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90638525","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510170191100
J. Redoulès, R. Bendaoud, A. Fert, D. Bertrand, J. Vétel, J. Lasjaunias, J. Souletie, J. Ferré
The critical behaviour of the Ising spin glass Fe 0.3 Mg 0.7 Cl 2 has been studied by d.c. magnetisation, a.c. susceptibility and specific heat measurements. We have extended the range of our previous a.c. susceptibility measurements down to 0.02 Hz by using a new set up which utilises the possibilities of a 16 bit analog to digital converter. The relaxation time τ and the coefficients a 3 and a 5 of the non linear susceptibilities are powers of each other and diverge like exponential functions of θ/T. This confirms our former statement that Fe 0.3 Mg 0.7 Cl 2 is of a class different from that of traditional 3d systems and appears as an example of a real 2d Ising spin glass with T c =0. We claim that the essential L'etude du comportement critique du verre de spin Ising Fe 0.3 Mg 0.7 a ete realisee a l'aide de mesures d'aimantation, de susceptibilite alternative et de chaleur specifique. Les mesures de susceptibilite alternative ont ete effectuees jusqu'a de tres basses frequences (0.02Hz
用直流磁化、交流磁化率和比热测量等方法研究了Ising自旋玻璃Fe 0.3 Mg 0.7 Cl 2的临界性能。我们通过使用一种利用16位模拟数字转换器的新设置，将我们以前的交流磁化率测量范围扩展到0.02 Hz。弛豫时间τ和非线性磁化率系数a3和a5是彼此的幂函数，并像θ/T的指数函数一样发散。这证实了我们之前的说法，即Fe 0.3 Mg 0.7 Cl 2属于与传统三维体系不同的一类，并作为一个实际的二维Ising自旋玻璃的例子，其tc =0。我们认为，基本的L’etude du comcomement critique du verre de spin Ising Fe 0.3 Mg 0.7是由L’etude de measuring d’amationd’amationd、敏感性alternative和挑战特异性实现的。Les测量的敏感替代效应仅为3个低音频率(0.02Hz
{"title":"Static and dynamic evidence for a transition at Tc = 0 in the Ising spin glass Fe0.3Mg0.7Cl2","authors":"J. Redoulès, R. Bendaoud, A. Fert, D. Bertrand, J. Vétel, J. Lasjaunias, J. Souletie, J. Ferré","doi":"10.1051/JPHYS:0199000510170191100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510170191100","url":null,"abstract":"The critical behaviour of the Ising spin glass Fe 0.3 Mg 0.7 Cl 2 has been studied by d.c. magnetisation, a.c. susceptibility and specific heat measurements. We have extended the range of our previous a.c. susceptibility measurements down to 0.02 Hz by using a new set up which utilises the possibilities of a 16 bit analog to digital converter. The relaxation time τ and the coefficients a 3 and a 5 of the non linear susceptibilities are powers of each other and diverge like exponential functions of θ/T. This confirms our former statement that Fe 0.3 Mg 0.7 Cl 2 is of a class different from that of traditional 3d systems and appears as an example of a real 2d Ising spin glass with T c =0. We claim that the essential L'etude du comportement critique du verre de spin Ising Fe 0.3 Mg 0.7 a ete realisee a l'aide de mesures d'aimantation, de susceptibilite alternative et de chaleur specifique. Les mesures de susceptibilite alternative ont ete effectuees jusqu'a de tres basses frequences (0.02Hz<f<3000Hz) grâce a la mise au point d'un dispositif experimental utilisant un convertisseur analogique numerique 16 bits rapide. Le temps de relaxation τ comme les coefficients a 3 et a 5 de la susceptibilite non lineaire sont puissances l'un de l'autre et divergent comme des exponentielles de θ/T. L'analyse des resultats confirme donc les conclusions d'une premiere etude du comportement critique dynamique : Fe 0.30 Mg 0.70 Cl 2 appartient a une classe d'universalite differente des systemes 3d et apparait comme exemple de verre de spin 2d Ising caracterise par une transition de phase a T c =0. Nous affirmons que les singularites observees apparaissent comme la limite naturelle a T c =0 des lois habituelles de «scaling». Nous nous differencions sur ce point des analyses presentees recemment pour d'autres systemes, ou un comportement semblable est interprete par une theorie ad hoc pour T c =0","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"28 1","pages":"1911-1928"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82921190","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510170179700
Eva Koscielny-Bunde
We study pattern recognition in linear Hopfield type networks of N neurons where each neuron is connected to the z subsequent neurons such that the state of the i th neuron at time t+1 is determined by the states of neurons i+1, ..., i+z at time t. We find that for small values of z/N the retrieval behavior differs considerably from the behavior of diluted Hopfield networks. The maximum number of random patterns that can be retrieved increases in a non linear way with z and the asymptotic mean overlap between input and output patterns decreases sharply as z is decreased and reaches zero at a finite value of z
{"title":"Pattern recognition in Hopfield type networks with a finite range of connections","authors":"Eva Koscielny-Bunde","doi":"10.1051/JPHYS:0199000510170179700","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510170179700","url":null,"abstract":"We study pattern recognition in linear Hopfield type networks of N neurons where each neuron is connected to the z subsequent neurons such that the state of the i th neuron at time t+1 is determined by the states of neurons i+1, ..., i+z at time t. We find that for small values of z/N the retrieval behavior differs considerably from the behavior of diluted Hopfield networks. The maximum number of random patterns that can be retrieved increases in a non linear way with z and the asymptotic mean overlap between input and output patterns decreases sharply as z is decreased and reaches zero at a finite value of z","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"28 1","pages":"1797-1801"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84764807","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}
Pub Date : 1990-09-01DOI: 10.1051/JPHYS:0199000510170196100
A. Razafitianamaharavo, P. Convert, J. Coulomb, B. Croset, N. Dupont-Pavlovsky
The structural characterization of the composite film formed by physisorption of krypton on (0001) graphite pre-plated with a monolayer of cyclohexane has been performed by neutron and X-ray diffraction. The organization of the composite film predicted by means of volumetric measurements on a very uniform surface (exfoliated graphite) is mostly preserved on compressed exfoliated graphite (Papyex) used for diffraction experiments in spite of enhanced difficulties in reaching the adsorption equilibrium, resulting from the Papyex density. Krypton adsorption at 77 K results in the compression of the pre-adsorbed cyclohexane layer to its densest state, followed by its partial displacement and the formation of three-dimensional crystallites. The fraction of cyclohexane remaining in the adsorbed state is involved in a two-dimensional solution with krypton, of √3 x √3 commensurate structure. Beyond the first layer, krypton adsorbs on itself.
{"title":"Structural characterization of krypton physisorption on (0001) graphite pre-plated with cyclohexane","authors":"A. Razafitianamaharavo, P. Convert, J. Coulomb, B. Croset, N. Dupont-Pavlovsky","doi":"10.1051/JPHYS:0199000510170196100","DOIUrl":"https://doi.org/10.1051/JPHYS:0199000510170196100","url":null,"abstract":"The structural characterization of the composite film formed by physisorption of krypton on (0001) graphite pre-plated with a monolayer of cyclohexane has been performed by neutron and X-ray diffraction. The organization of the composite film predicted by means of volumetric measurements on a very uniform surface (exfoliated graphite) is mostly preserved on compressed exfoliated graphite (Papyex) used for diffraction experiments in spite of enhanced difficulties in reaching the adsorption equilibrium, resulting from the Papyex density. Krypton adsorption at 77 K results in the compression of the pre-adsorbed cyclohexane layer to its densest state, followed by its partial displacement and the formation of three-dimensional crystallites. The fraction of cyclohexane remaining in the adsorbed state is involved in a two-dimensional solution with krypton, of √3 x √3 commensurate structure. Beyond the first layer, krypton adsorbs on itself.","PeriodicalId":14747,"journal":{"name":"Journal De Physique","volume":"5 1","pages":"1961-1969"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85047800","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}
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