Showing papers in "Physica D: Nonlinear Phenomena in 1968"

TL;DR: In this paper, a critical comparison of the theories of Foster, Weber and Jablonski is made and a new theory on excitation transfer within clusters of molecules is outlined.

TL;DR: In this article, the potential parameters, eij and σij, of the mixed interaction have been calculated from the experimental data and some combination rules connecting the mixed parameters with those of the pure components have been tested.

TL;DR: In this paper, an exact master equation (EME) of the markovian form for the diagonal part of the density operator is derived from quantum dynamical laws, which is valid for systems with a time-dependent Hamiltonian also.

TL;DR: In this article, the absolute cross sections of the excitation of helium from the ground state to n 1 S, n 1 D (n = 3, 4, 5, 6, 6) and n 1 P (n 2.5, 3.1, 4.4, 5.5) states by the impact of protons in the 1-150 keV energy region were determined.

TL;DR: In this article, the logarithmic divergencies, found in the density expansion of the diffusion coefficient of a Lorentz gas are renormalized by summing up the most divergent contributions.

TL;DR: In this paper, a description of the anisotropy energy with cubic harmonics is given and the first six constants in this description have been calculated at 296, 195, 77, 20 and 4.2 K.

TL;DR: The thermal conductivity of gaseous and liquid argon has been determined between 90 and 300°K at pressures from atmospheric to 500 kgf cm−2 using a vertical concentric cylinder apparatus as discussed by the authors.

TL;DR: In this paper, experiments in the temperature range 0.02 to 0.2°K are described which give direct evidence for Kapitza or thermal boundary resistance between foils and a slurry of chrome alum in oil, obeying the relation 3x10-6T-3A-1°K s/erg, and an extremely small thermal resistance in threaded mechanical copper-copper joints due to heat transfer by electrons.

TL;DR: In this paper, the rotational-translational relaxation times of parahydrogen with 3 He, 4 He, Ne, Ar, Kr, Xe and oH 2 were measured at several temperatures between 77 and 170°K in all cases a linear relationship was found between the inverse relaxation time and concentration.

TL;DR: In this article, a tensorial expansion for the determination of the thermal conductivity and viscosity of a dilute polyatomic gas which are odd in the angular momentum is decoupled from those which are even and hence vanish.

TL;DR: In this article, it is shown that a formulation of non-equilibrium statistical mechanics is possible to treat symmetrically homogeneous and inhomogeneous systems, vacuum and correlations.

TL;DR: In this paper, a generalization of the author's thermodynamic theory for mechanical phenomena in continuous media is given, based on the general methods of non-equilibrium thermodynamics.

TL;DR: In this paper, it is shown that for a system of finite size the energy does not transform as the fourth component of a 4-vector, as is assumed by some authors.

TL;DR: In this article, the Bethe-Born approximation is applied to the emission cross sections of the First Negative Band system of N2 when excited by electrons in the energy range of 0.1 to 6 keV, and a relatively strong contribution from collision-induced dipole transitions is found in the excitation process.

TL;DR: In this article, the free energy of low density plasmas at temperatures below a rydberg is derived using a semiclassical approximation, and an expression for the pressure of the plasma is derived.

TL;DR: In this paper, an adiabatic invariant for the particle's nearly periodic motion is derived, and it is shown that this invariant changes little, even during transition between the free and the trapped state for nearly all particles.

TL;DR: In this article, the angular dependence of the dissociation cross section of H2+ ions incident at 3-10 keV on rare gases and H2 was measured and the results showed qualitative agreement with theoretical predictions and also that for small internuclear distances in the H 2+ molecule the disassembly proceeds primarily from the 2pσu state.

TL;DR: In this article, the theory of Brownian motion in an inhomogeneous fluid is discussed within the framework of the method of one of the authors (DNZ) for the construction of the distribution function for a nonequilibrium system.

TL;DR: In this paper, the authors derived the transport properties of a dilute gas of polar molecules in the presence of a static homogenous electric field using as a starting point a form of the Waldmann-Snider transport equation.

TL;DR: The relativistic conservation laws of energy and momentum in a substance, which consists of atoms carrying both electric and magnetic dipoles, is derived from the microscopic force laws for point particles in the presence of an electromagnetic field.

TL;DR: The temperature dependence of the thermal diffusion factor for several isotopic mixtures of methane and argon and methane was studied in two swing separators between 80δK and 300δk as discussed by the authors.

TL;DR: In this paper, a simple apparatus suitable for measuring relative values of the coefficient of thermal conductivity of gases is described, which is obtained by measuring the variable heat input required in order to maintain a constant temperature gradient between a bead thermistor and the surrounding gas.

TL;DR: In this paper, it was shown that concavity of the entropy is a consequence of the second part of second principle and extensivity, and that the energy results to be convex, on the assumption that it be a monotonic function of entropy.

TL;DR: In this article, the second scattering of projectile and target atoms after a collision of keV Ar + ions on the surface of a Cu single crystal was observed and a simple potential model explains the results.

TL;DR: In this article, the positions of the 4 f 2 (5 d + 6 s ) configuration were calculated by means of 18 parameters with an rms error of 84 cm -1 (0.2%).

TL;DR: In this article, the isotope shift in six Dy I lines has been investigated by means of the technique of exchanging lightsources containing enriched isotope samples and a recording Fabry-Perot spectrometer with a digital output.

TL;DR: In this paper, the shape of the curves representing the voltage oscillations as a function of an applied magnetic field at constant applied current was investigated and shown to be in qualitative agreement with the calculated shape of critical current oscillations if one applies the basic Josephson relations to the multiple contact and neglects the self-inductances and mutual inductances of the holes between the contacts of the grating.

TL;DR: The literature on the relativistic energy-momentum tensor in polarized media falls apart in treatments based on microscopic first principles and considerations starting from macroscopic postulates as discussed by the authors.

TL;DR: In this article, the authors designed a crossed beam apparatus to measure the energy dependence of the cross sections for ionization of He from the metastable 2 3 S and 2 1 S states.

TL;DR: In this paper, the equilibrium between the solid and liquid phases of the argon-methane system has been investigated using the conventional calorimeter method of thermal analysis together with the heat capacity measurements.