Volume 31, Issue 2

In this series of notes, we introduce a new quantity into the theory of classical matter fields. Besides the usual energy-momentum tensor, we postulate the existence of a further dynamical attribute of matter, the 3rd rank tensor ⊿ ijk of hypermomentum. Subsequently, a general relativistic field theory of energy-momentum and hypermomentum is outlined. In Part I we motivate the need for hypermomentum. We split it into spin angular momentum, the dilatation hypermomentum, and traceless proper hypermomentum and discuss their physical meanings and conservation laws.

Rotating activation foils with resonance energies of 1.26 eV and 5.19 eV have been applied for exact measurements of neutron cross sections. The detector consisted of a sandwich of two rotating foils and was suitable for determining exactly the neutron flux at the resonance energy and energy changes in the neutron beam. The cross sections of polycrystalline samples showed uncertainties greater than the statistical error. The more accurate measurements on liquid samples yielded the following scattering cross sections of free atoms for neutrons of zero energy: Lead: σ 0 (Pb) = (11.261 ±0.006) b, Bismuth: σ 0 (Bi) = (9.300±0.003) b, and Sulfur: σ 0 (S) = (0.985 ±0.004) b. These data are of interest for an investigation of the neutron-electron interaction.

Paramagnetic ions with hyperfine interaction generally have an involved ESR-spectrum. For host lattices of cubic symmetry it will be shown that while going from single crystals to powdered systems the true spin quantum number S can be substituted by an effective spin quantum number S' = ½. Using an isotropic spin Hamilton operator the energy-levels and their eigenfunctions as well as the transition probabilities are calculated explitely. The model is then applied to the ESR-spectrum of manganese-doped polycrystalline CaO. The theoretical spectrum fits the experimental up to 2·10 -5 and is in every respect comparable to results of the 3 rd order perturbation theory. Above all the model reproduces the true values for the g-factor and the hyperfine coupling constant A as known from single crystal investigations. This is also verified for Mn 2+ -ions on cubic sites of MgO and BaO.

The rotational spectrum of BaS was measured in the frequency range from 55 to 68 GHz, with a heated absorption cell up to 2000 K and a saturation modulation technique. The derived rotational constants and potential coefficients are given.

Explicit relations between the spectroscopic constants, A͂ , B͂ , C͂, ⊿ J ,⊿ JK , ⊿ K , δ J , and δ K , obtained by the application of the various reduction procedures of the effective rotational Hamil­tonian are given in matrix formulation. Watson’s reduction procedures for the three different axis representations I r , II r , and III r have been considered as well as the reduction making R͂ 5 = 0, in­stead of R͂ 6 = 0. The ambiguity in the determination of the τ’s arising from the use of planarity conditions is discussed in relation to the τ defect.

A simple parameter is proposed for expressing the quasilinearity of molecules in a quantitative way. The parameter γ 0 is defined on the basis of a discussion of the separation of variables in the Born-Oppenheimer approximation. The parameter γ 0 assumes the value +1 for bent molecules and -1 for linear molecules. The range from -1 to +1 traces the transition of a vibrational degree of freedom in the linear configuration of a polyatomic molecule into a rotational degree of freedom in the bent configuration. The sequence of molecules along this parameter is shown and model calculations are carried out to further illustrate the physical interpretation of the parameter.

A rotational analysis of several bands of the D←X system of 123 Sb− 123 Sb is carried out. It is shown that the hitherto assumed vibrational classification of the D←X system is certainly incorrect, as well as a previously given value for the rotational constant of the X state. B(X 1 ∑ g + , ν=0) is found equal to 0.044263 cm -1 . The perturbations appearing in the various vibrational levels are interpreted in terms of interactions with a new electronic state, labelled L.

Temperature The temperature of the neutral gas (T Gas ) in an unipolar HF-discharge excited in argon at atmospheric pressure is measured by Mach-Zehnder-interferences. This value of the temperature can be compared with theoretical results concerning the relation between T Gas , T rot and T e in dependence of the electron density N e .

The Barkhausen-Spectra of pure iron have been measured for four recrystallized wire specimens of different grain size. The pulse size distributions show a strong dependence on this parameter. The number of the Barkhausen-pulses increases with decreasing grain size. The comparison of the spectra measured at an external field in the vicinity of the coercive force with those measured at a field where domain rotation begins shows that in the latter region the size and number of jumps is larger. Measurements of the counting rate of the Barkhausen jumps versus the external magnetic field show two maxima instead of normally one at the coercive force. This unusual behaviour could be explained with the successive change of Bloch wall types in certain sections of the hysteresis loop and their different interaction with dislocations.

The proton ENDOR spectra of various phenyl substituted hydrocarbon radicals in solution show a marked temperature dependence of the positions, widths, and amplitudes of particular lines. These effects are analyzed in terms of three relaxation mechanisms: (i) internal hindered rotation and (ii) torsional oscillations of the phenyl rings, and (iii) molecular tumbling. From the tempera-ture dependence of relaxation effects caused by mechanism (i) hindrance potentials for internal rotation of phenyl rings could be determined. The results are in good agreement with the pre-dictions of simple π-MO theory. Relaxation effects caused by (ii) turned out to be negligible. Mechanism (iii) produces strong variations in linewidths at low temperatures due to the different hyperfine anisotropics depending on nuclear position.

Two principally different molecular structures in the crystalline state are known from the copper (II) complex with 7-hydroxy-4-methyl-5-aza-hept-4-en-2-on. The magnetic susceptibilities of three forms of this compound [α-(CuEIA) 4 , β-(CuEIA) 4 , and β-(CuEIA) 4 ·2 C 6 H 6 ] have been measured in the temperature range 2.6-300 K. The results indicate that principally different molecular structures correspond to principally different magnetic properties. While the α-form shows antiferromagnetic spin coupling in the S′ = 0 ground state, the electrons in the β-form are coupled ferromagnetically in the S′ = 2 ground state. A fitting procedure of a theoretical equation based on the isotropic HDVV-model led to a satisfactory agreement between calculated and experimental data for α-(CuEIA) 4 and β-(CuEIA) 4 , while this was not possible for β-(CuEIA) 4 ·2C 6 H 6 . The exchange parameters obtained for α-(CuEIA) 4 (g=2.13, J 12 = -17cm -1 , J 13 =+3.5cm -1 , and N a =60-10 -8 cgs-emu) are in good agreement with the values given by Ginsberg et al. For β-(CuEIA) 4 a weak antiferromagnetic intercluster interaction could be determined at low tempera­tures. The fitting procedure yielded the following values: g=2.05, J 12 =-6.4 cm -1 , J 13 =+24.2 cm -1 , N a =10·10 -6 cgs-emu, ⊖=-0.27°.

Gold films of 400 Å thickness were evaporated under UHV-conditions on (111)-, (110)-and (100)-oriented silicon substrates and were subsequently investigated by x-ray diffraction. Mainly the influence of orientation and cleanliness of the substrate on film structure was studied. Informations on the orientation and size of the crystallites as well as on lattice distortions were obtained by analysing intensity, angular displacement and width of the diffraction peaks. It is found that the gold films show a preferred (111)-orientation in all cases; only the degree of orienta-tion changes with the pretreatment of the substrate. The size of the (111)-oriented crystallites cor-responds to the film thickness, and a noticeable density of intrinsic stacking faults can be detected.

The texture of 400 Å thick gold films was investigated by plotting the intensities obtained with the help of a texture analyser in a pole figure diagramm. The films had been evaporated under UHV conditions on (111)-, (110)-and (100)-oriented silicon substrates. The gold films always show a preferred (111)-orientation. This preferred orientation, however, may manifest itself in a (111) fibre texture or a single crystal structure due to different orientation and heating pretreatment of the substrate. Quantitative statements are given on crystal misorienta-tion and azimuthal alignment. The sixfold symmetry of the pole figures can be traced back to the influence of twin stacking faults.

The radial temperature distribution in a Hg-high-pressure discharge with metal halogene additives (Sn-, Zn-Iodide) has been measured. Three different spectroscopic methods (Emission-, Absorption-, Bartels-and 2-lines-Method) are compared. The influence of the silica bulb is discussed. High incidence angles for the absorption measurements are realized by use of an elliptic mirror. Emission and absorption measurements in a definite time intervall of the 50 Hz-discharge current was done with signal averaging technique. The arc shows a constriction which is discussed.

In water t-butanol mixtures hypersound velocities and hypersound damping were measured at 25 °C by Brillouin scattering. From a comparison of the results of this work with ultrasonic data the velocity dispersion, the nonrelaxing and the relaxing fraction of the bulk - viscosity, and the relaxation frequency were calculated.

The oxidation of polycrystalline samples of Ni/Pd-alloys at 600 °C and 2·10 -5 Torr O 2 has been investigated by means of Auger electron spectroscopy and soft x-ray appearance potential spectroscopy. The clean surfaces are enriched by Pd; and with increasing Pd content the binding energy of the Ni 2p-core levels was found to decrease continuously by 0.7 eV. After completion of the oxidation identical overlayers were formed on all samples (except on pure Pd!) which were identified to consist of NiO. Within the depth probed by the applied techniques (≲20 Å) the rate of oxidation was found to increase with increasing Pd content, which is in contrast to the behaviour to be expected for the growth of thick oxide layers after the formation of a coherent NiO overlayer.

The energies of the muonic 2−1 and 3−2 transitions in Cd and Br have been measured. The c-parameter of the (c, t) Fermi distribution was determined. Energies and inten-sities of nuclear gamma rays in Se are given.

The electrical resistivity of thin single crystal aluminium samples has been measured in a transverse magnetic field at 4.2 K. The magnetoresistance shows Sondheimer and mag-netic breakdown oscillations.

Previous investigations of the range of the birefringent phase of mixed crystals having at room temperature the symmetry Pm3m of NH 4 Cl or NH 4 Br with simple halides of monovalent cations and the same anion are extended to the nonisomorphic partners KBr, RbBr or RbCl. The disappear-ance of the inversion symmetry in the cubic low temperature phase has been proved by experiment.

A simple method is described for separating "through-space" from "through-bond" interactions. The method is applied to 1,4-cyclohexadiene, 2,5-dihydrofuran, 2,5-dihydro-thiophene, and 2,5-dihydropyrrole.

Mean Amplitudes of Vibration for the Tetrahalogeno Aluminates Mean amplitudes of vibration for the A1X4~ ions (X = F, CI, Br, I) have been calculated from known spectroscopic data, using the L-Matrix Method. The results are briefly discussed, especially in relation with those of isoelectronic species.

Interaction energies of six trivalent cation impurity-cation vacancy configurations in KCl have been evaluated and compared with experimental data.