Le Journal Research Articles

Correlation effects in the bulk modulus and equilibrium lattice spacing of the transition metals

2014 The role of correlations in the bulk modulus and equilibrium lattice spacing of the transition metals is studied using a perturbation method related to Gutzwiller’s approximation and is found to decrease the bulk modulus and increase the lattice spacing, the effect being greatest in the middle of the 3d series in agreement with experiment. LE JOURNAL DE PHYSIQUE LETTRES TOME 38, .ler JUILLET 1977, Classification Physics Abstracts 62.20D 71.45 As is seen in figure 1 the bulk modulus in the 4d and 5d transition metal series varies regularly with the

Complément à l'étude thermodynamique de sels fondus à anion polyatomique

2014 By using recent measurements, either original or found in the literature, alkali nitrates are shown to exhibit a rather high compactness marked by a low coefficient of compressibility (from 2 to 3 10-10 Pa-1), a small free volume (from 0.8 to 2.2 A3) and a high internal pressure (about 0.1 x 1010 Pa). Their heat capacity at constant volume goes from 26 to 30 cal mol-1 K-1. They behave in the same way as salts involving tetrahedral polyanions do. LE JOURNAL DE PHYSIQUE LETTRES TOME 38, 15 JANVIER 1977, Classification Physics Abstracts 7.126 7.200 7.500

Surface disclination lines observed in nematic liquid crystals when the surfaces induce homogeneously tilted alignment

2014 A topological study of the symmetry transformations on a surface inducing both tilted and homogeneous orientation in nematic liquid crystals is presented. It predicts the existence of two types of surface disclination lines, which have been observed experimentally. The evaluation of their strength (which does not satisfy the rule S = k 1/2 where k is an integer) required a special definition of this quantity. Their relative positions and interactions are well interpreted in terms of grain boundaries on the surface considered as an ordered two-dimensional medium. The evaluation of the elastic energies of those lines can only be very approximate, due to our ignorance of the anchoring energies. LE JOURNAL DE PHYSIQUE TOME 38, MAI 1977,

On the microscopic interpretation of flexoelectricity

2014 Recognition of the importance of electric quadrupoles allows a new interpretation of the flexoelectric phenomenon to be proposed. Meyer’s model and the influence of charge are also discussed. LE JOURNAL DE PHYSIQUE TOME 38, MARS 1977, Classification Physics Abstracts 7.130

Mécanismes de piégeage et effets de proximité dans des échantillons monograins d'alliages eutectiques lamellaires orientés

2014 Magnetization measurements, carried out on monograined bulk samples of a lamellar Pb-Sn eutectic alloy for lamellar spacings aE in the range 1.5 03BCm to 5 03BCm, have shown that the Sn lamellae remain diamagnetic up to 7 K, which proves the existence of a very strong proximity effect. The magnetization curves can be explained assuming a preponderant pinning at the numerous Sn/Pb interfaces. The Ic(H) curves obtained on Pb-Sn or ln2Bi-In 20 03BCm thick films having a perfect lamellar structure (1.5 03BCm aE 10 03BCm ; I // lamellae ; H // lamellae and I) exhibit a peculiar behaviour in the small-field range : Ic remains constant for fields increasing up to a certain value H1 (~ 50 Oe at 4.2 K). This behaviour can be related to the successive potential barriers, due to the interfaces, for the vortices. The major role of these interfaces is confirmed by the study of the bulk pinning force Fp(b) ~ b1⁄2(1 b), b = H/Hc2 ; this peculiar b dependence is indeed typical of pinning at N/S boundaries. LE JOURNAL DE PHYSIQUE TOME 38, AVRIL 1977,

Destruction par chocs électroniques des atomes métastables et pseudo-métastables de néon dans une colonne positive

2014 The population frequency response of the 1s3, 1s4, 1s5 levels of Neon to a weak modulation of the discharge current has been studied in the positive column of a glow discharge. The following values are found for the deexcitation coefficients by electron impact : 03B2(1s3) = 03B2(1s5) = (10.4 ± 2) 10-7 cm3.s-1 03B2(1s4) = (27 ± 4) 10-7 cm3.s-1. LE JOURNAL DE PHYSIQUE LETTRES TOME 38, ler OCTOBRE 1977, Classification Physics Abstracts 34. 80D ,

Low energy interband transitions in aluminium

Low energy interband transitions in aluminium

Mössbauer study of the magnetic properties of Fe2-xM xP1-yAsy type compounds, M = Cr, Mn, Fe, Co, Ni

2014 The series of phosphides and arsenophosphides of the first row transition metals with formula Fe2-xMxP1-yAsy is studied by Mossbauer spectrometry. The question of the attribution of the quadrupolar couplings to both sites of Fe2P is solved, by applying the technique of polarization. All the compounds of the series Cr2P1yAsy (1 % 57Fe), the phosphides Ni2P (1 % 57Fe) and FeNiP are found paramagnetic down to 77 K. The Neel points of the compounds Mn2P1-yAsy and FeMnP are determined in rather good agreement with the previous measurements. The compound CO2P distinguishes itself by its sensitivity to the stoichiometry, indeed an addition of 5 % of phosphorus does abruptly decrease the Curie point. LE JOURNAL DE PHYSIQUE TOME 38, JANVIER 1977,

Scaling at low temperatures in the Ginzburg-Landau model

2014 The n-component Landau-Ginzburg model with short range forces is examined for dimensionalities d less than two. For d, n such that Tc = 0, its solution reduces to the solution of the continuous Heisenberg-like model. The critical exponents and corresponding scaling laws are found for the Tc = 0 transitions and in particular ~ = 2 2014 d. LE JOURNAL DE PHYSIQUE LETTRES TOME 38, 15 JANVIER 1977, Classification Physics Abstracts 1.680 Much of the current work on phase transitions [1-3] is based upon the d-dimensional Ginzburg-Landau (G-L) functional H[ q>(x)] = acp2(x) + b~P4(x) + c[o~p(x)J2 . (1) Here ~p(x) is the n-component classical order parameter. Usually one assumes a = a’(T TMF) and a’, TMF, b and c, positive and finite. In fact, our derivation is valid under somewhat less restrictive requirements on a, b, c which will be stated in the course of the work. In general, the above functional has to be associated with a large momentum cut-off Q. This cut-off is required for ~ ~ 2, where it regularizes the ultraviolet singularities. The well known procedure which deals with the cut-off Q in the region 2 d 4 is the renormalization group [2, 4]. However, as has been already realized for d = 1 [1, 3, 5], for d 2 the ultraviolet singularities are absent, i.e. the cut-off can be omitted (Q = oo). The infrared singularities we have to deal with (for d 2) make Fe vanish at d 2, n = oo, without invalidating the G-L model itself [6]. The model also proved meaningful [1, 3, 5] for d = 1 and n arbitrary [1], and the present paper interpolates between the ~= 1, ~ > 1 [1, 5] and the n = oo, d 2 [6] results.

Permittivité des diélectriques amorphes formés de molécules polaires anisotropes

An analysis of the local field inside an ellipsoidal cavity embedded in an amorphous dielectric is given on a new basis. The results obtained are used to evaluate the permittivity of dielectrics composed of anisotropic polar molecules. The anisotropies of shape and of polarisability are considered as being independent while the permanent dipole moment is taken with arbitrary orientation. Consequently this extension of the formulae of Onsager, Scholte or Thiebaut, Rivail and Barriol has a highly general character. LE JOURNAL DE PHYSIQUE TOME 37, FtviuER 1976, I Classification Physics Abstracts 8.720

On the dissociation of hexagonal interstitial frank loops

2014 Some preliminary results of equilibrium energy computations of dissociated interstitial Frank loops are presented. It is argued that interstitial defects could dissociate into acute or obtuse angle configurations. The stability of the obtuse configuration should then depend on the intrinsic-extrinsic stacking fault energy ratio p. To quantitatively explore these ideas, the equilibrium energy of hexagonal interstitial loops has been calculated in silicon and it is shown that for large sizes (~ 2 000 A) a small difference between 03B3E and 03B3I (03B3I/03B3E ~ 0.9) makes the obtuse configuration more stable. It is therefore likely that the large interstitial hexagonal loops observed in irradiated materials have the obtuseangle configuration. A method for determining the 03B3I/03B3E ratio based on these results is suggested. LE JOURNAL DE PHYSIQUE TOME 37, DTCEMBRE 1976, Classification Physics Abstracts 9.126

Effet Zeeman des niveaux 3P de l'hélium

2014 We have observed level-crossing resonances in the 3P states (n = 2, 3, 4) of helium, excited and aligned by neutral impact in high magnetic field. The results of the Zeeman effect theory for many electron atoms including motional, relativistic and radiative corrections to the order m/M 03BCB H and 03B13 03BCB H respectively are explicitly formulated and analysed into irreducible tensorial sets. All the parameters of the problem are evaluated using quasihydrogenic radial wave functions. The following results have been derived : in the 2 3P state, the experimental g’L factor : g’L(2 3p) = 0.999 867 8 ± 2.9 x 10-6 in the 3 3P and 4 3P, the fine structure E02 : E02(3 3P) = 8 772.565 ± 0.062 MHz E02(4 3p) = 3 576.475 ± 0.075 MHz. LE JOURNAL DE PHYSIQUE TOME 37, AVRIL 1976, Classification Physics Abstracts 5.230

Méthode tensorielle de calcul des intensités des raies d'absorption I.R. d'une molécule XY4 tétraédrique. exemples d'application

2014 Intensities of absorption vibration-rotation transitions are calculated using a tensorial formalism both for the vibration-rotation eigenfunctions and for the electric dipole moment of XY4 tetrahedral molecules, whence Wigner-Eckart’s theorem can be applied to calculate the matrix elements of the dipole moment. Nuclear statistical weights are determined using representations of the permutation group S4. It is shown that the expressions appearing in the calculation can be simplified by a precise definition of the conventional symmetries. Finally, a detailed calculation of the intensities is explicitly given for the fundamental bands 03BD3 and 03BD4 and the combination band (03BD3 + 03BD4). LE JOURNAL DE PHYSIQUE TOME 37, NOVEMBRE 1976, Classification Physics Abstracts 5.444

On the origin of a strong central peak in the local density of d states at the surface of transition metals

2014 The central peak observed on the (100) surfaces of Mo and W cannot be thought of as due to a van Hove anomaly of the d band of the surface atomic plane, broadened by interaction with the volume of the metal. It is argued that it might be considered as due to virtual d states on the surface atoms, broadened by interaction with the volume of the metal. A basic difference between closepacked and not so closepacked surfaces in stressed in this connection. Other cases where surface peaks have been computed in the LCAO approximation are also considered. LE JOURNAL DE PHYSIQUE TOME 37, JUILLET-AOiJT 1976, Classification Physics Abstracts 8.322

Neutron diffraction studies of liquid silver and liquid Ag-Ge alloys

2014 Structural studies of liquid Ag at 1 323 K and liquid Ag-Ge alloys at 1 123 K have been carried out by means of neutron diffraction. The pair correlation functions were evaluated by means of a Fourier transform and coordination numbers were calculated. The interference functions are compared with those deduced from Percus-Yevick calculation. Using the assumption of concentration independency, partial interference functions are evaluated for Ag-Ag and Ge-Ge pairs. They are shown to be very similar to the respective structure factors of liquid silver and liquid germanium. LE JOURNAL DE PHYSIQUE TOME 37, DECEMBRE 1976, Classification Physics Abstracts 7.126

Systèmes de glissement au cours de la déformation plastique de Cu 2O

2014 Constant strain rate compression tests have been performed on single crystal cuprous oxide Cu2O between room temperature and 800 °C. The slip systems { 011} 011> and { 100 } 010 > were activated by stress applied in the 001 > and 110 > directions respectively. LE JOURNAL DE PHYSIQUE TOME 37, JUILLET-AOUT 1976,

Satellite NMR study of the dynamic susceptibility of Fe in Cu above and below Tk

2014 NMR relaxation times T1 of 63Cu satellites corresponding to 1st, 2nd and 3rd nearest neighbours of Fe in Cu-Fe dilute alloys have been measured in 55 kG for 1.2 K T 310 K. These data allow a direct determination of the relaxation rate 03C4-1 of the local magnetization of Fe. It is found to change from a constant value which characterizes the strong coupling state of Fe below TK to a Korringa like behaviour 03C4-1 03B1T for T ~ TK, as qualitatively expected from theoretical calculations on Kondo effect. LE JOURNAL DE PHYSIQUE LETTRES Classification Physics Abstracts 8 . 526 8 . 664 8 . 630 TOME 37, SEPTEMBRE 1976, It has been clear for a long time that spin flip processes and consequently the fluctuations of the local magnetization play a major role in the establishment of the Kondo state of transition metal impurities in noble metal matrices [1]. It has thus been a great challenge for experimentalists to measure the frequency dependence of the local susceptibility, or at least its spectral width, which in ideal cases can be identified with the inverse of a spin autocorrelation time T (or spin lattice relaxation time in spin resonance terminology). A great number of experimental techniques such as ESR [2], impurity [3] or host NMR [4, 5], Mossbauer effect [6], and neutron scattering [7] have been used to determine i-1 in various characteristic systems. However up to now such experiments were only successful for limited ranges of temperature, either r ~ TK or T ~ TK. In the classic CuFe Kondo system for which TK ~ 30 K, recent nuclear spin lattice’relaxation data for the near neighbour ~ 3Cu nuclei of Fe showed that for 7 ~ TK z has a constant value ’[-1 f’OoJ kB 7~/~ [5]. In this letter we present an extension of these measurements to room temperature, where for the first time the variation of i -1 could be accurately followed from well below to well above TK (30 K). Measurements have been carried out with pulse NMR techniques at about 60 MHz on the three 63CU satellites A, M, B [8] which correspond to the 1 st, (*) Laboratoire associe au C.N.R.S. 2nd and 3rd nearest neighbours to Fe. Full details of the experimental technique will be reported elsewhere. Here the physical significance of the nuclear T1 data which are summarized in figure 1 will be discussed. For satellite B data could be taken for a large range of concentration, showing that the measured T1 values are characteristic of neighbours of isolated impurities. T1-1 is proportional to T below 4.2 K, goes through a maximum ( ~ 50 K) then a minimum ( ~ 150 K) and finally approaches the pure copper Korringa rate (TiK T = 1.28 s K) at higher temperature. The shorter relaxation times and lower sensitivity make T1 measurements more difficult and less accurate for the first and second nearest neighbours. It was shown in ref. [5] that, at low T, for various satellites, the relaxation is dominated by impurity induced relaxation due to isotropic hyperfine coupling with the transverse fluctuations of the impurity magnetization. For a shell of neighbours at distance r from the impurity this extra relaxation rate is given by : where XT(W) is the transverse susceptibility of the impurity and WD the nuclear Larmor frequency. The isotropic transferred hyperfine coupling constant As(r) can be deduced from the differential Knight Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyslet:01976003709020500 L-206 JOURNAL DE PHYSIQUE LETTRES FIG.1. NMR relaxation rates of the 1 st (A), 2nd (M) and 3rd (B) shells of neighbours of Fe in Cu measured near 55 kG. The impurity induced relaxation rate (7~?)’~ is obtained by subtracting the Korringa rate (TIK) ’ of pure Cu. The dashed lines for satellites A and M are deduced from the solid line (which approximates the data for B), by assuming that (T’mP)-’ scales with (âK)2. shift of each shell of nuclei with respect to pure

The Contribution of the French Literary Avant-Garde to Film Theory and Criticism (1907-1924)

When did serious writers of literature really discover the cinema? The place was France; the time, just before and during the First World War. The principals were two different generations of poets in the Parisian avantgarde. Although similar phenomena occurred elsewhere about this timeItaly (Bruno Corra, F. T. Marinetti), the United States (Vachel Lindsay, Hugo Munsterberg), Russia (Vladimir Mayakovsky), and Sweden (Bo Bergman)-what happened in France was unique in scope and intensity. Its importance was twofold. This discovery would affect the embryonic development of French film aesthetics-with very different contributions from each generation of the avant-garde. And it would influence significantly the work of the poets themselves. Previous studies have sketched or touched on certain points of this discovery, but none has given it the attention it deserves.1 One of the bestJ. H. Matthews' Surrealism and Film-even concludes that, though quite number of the avant-garde poets were eager to learn from film, there is not much evidence of [their] ability to bring anything to the cinema in return.2 The following pages offer an opposing view. At the beginning of the century, in France as in the United States, writers generally considered the cinema a charming distraction (Georges Courteline, Le Journal, October 24, 1913). Its unusual popularity was explained with characteristic disdain as laziness in the case of anyone who doesn't use his head during the day and has no wish to change the routine at night, and desire for rest in the case of the intellectual upon whom daily life weighs so heavily!3 (Roger Lalli, La Flora, October 15, 1912). And

The vibration-rotation bands v2 and v5 of methyl bromide

2014 The infrared spectrum of CH3Br has been analyzed between 1 200 and 1 500 cmtaking into account the x y Coriolis resonance between the two fundamental levels 03C52 = 1 and 03C55 = 1. The band centers were found respectively at 1 305.907 and 1 442.885 cm-1 and the 03B6x2,5 coupling term was determined to be 0.617. LE JOURNAL DE PHYSIQUE TOME 36, SEPTEMBRE 1975, 1 Classification Physics Abstracts 5.444

Spectre de niveaux d'ions moléculaires à la limite des fortes énergies intra-atomiques de corrélation

2014 We extend to small clusters a method of calculating the energy of the ground and excited states in the limit of an infinite intra-atomic correlation energy U. The technique is explicitly developed for three polygonal-shaped ions with 3, 4 and 6 atoms and for an ion with 4 atoms and a different shape. The results show that the stablest shapes are not the same as those obtained in the Huckel approximation. For a given shape, they also differ according to the total spin. LE JOURNAL DE PHYSIQUE TOME 36, MAI 1975, Classification Physics Abstracts 8.535 8.980