Showing papers by "Chalmers University of Technology published in 1972"
TL;DR: The increase in oxidation-reduction potential of the Type 1 copper and the two-electron acceptor in the presence of excess hexacyanoferrate seems to be due to a specific reduction of Type 2 copper by the hexacynoferrate (II).
271 citations
236 citations
TL;DR: In this article, the authors compared the spectral data of water vapor and carbon dioxide with Hottel's total emissivity charts, and showed that the latter is not reliable as a standard for comparison.
235 citations
TL;DR: In this paper, an analytical theory for the switching time constant of thin oxide MNOS structures is derived and curves of the switching-time constant versus the nitride field are computed, which are useful in the design of MNOS-memory transistors.
Abstract: The properties of thin oxide MNOS structures are studied. An analytical theory for the switching time constant is derived and curves of the switching time constant versus the nitride field are computed. These curves are useful in the design of MNOS-memory transistors. The theory is compared with experiments. The normal current in the thin oxide MNOS structures is assumed to be a modified Fowler-Nordheim current. At small oxide thicknesses and low nitride field, an additional current is shown to exist that is attributed to direct tunneling into traps in the nitride. The discharge of MNOS structures is briefly discussed and is shown to be due to a direct tunneling of charge carriers from traps in the nitride into the semiconductor.
136 citations
105 citations
TL;DR: In this paper, the Fourier coefficient of the pseudopotential mod U200 mod has been derived and its temperature variation satisfactorily explained and the derived value of this coefficient for 0 K is 0.79+or- 0.01 eV which is somewhat higher than that obtained from Fermi surface data, but the difference may in part be due to an energy dependence of the coefficient.
Abstract: Measurements of the optical absorption of clean evaporated aluminium films have been made at several different temperatures and the results interpreted in terms of the theory of parallel band absorption. Values of the Fourier coefficient of the pseudopotential mod U200 mod have been derived and its temperature variation satisfactorily explained. The derived value of this coefficient for 0 K is 0.79+or- 0.01 eV which is somewhat higher than that obtained from Fermi surface data, but the difference may in part be due to an energy dependence of the coefficient. Values of optical mass, interband and Drude relaxation times at the different temperatures have been derived. Some data appropriate to partially disordered films are also presented.
80 citations
TL;DR: In this paper, the surface energy of particles can be estimated directly from the lateral spread of the fringes (as measured on the micrographs) and knowledge of the elastic modulus of the metal, and small changes induced in the contact geometry between the metal surfaces (e.g., due to plastic deformation) can substantially increase the adhesion at the junction.
78 citations
TL;DR: In this article, a geometrical model for sintering nickel-doped tungsten is proposed, which consists of a pendular ring at the tungstern neck surface plus a nickel-enriched grain boundary, and the force equation contains two additional terms to account for the effect of surface tension at the nickel-vapor interface, including a factor for the dihedral angle.
Abstract: A geometrical model for sintering nickel-doped tungsten is proposed which consists of a pendular ring at the tungsten neck surface plus a nickel-enriched tungsten grain boundary. As compared to Kingery's model, the force equation contains two additional terms to account for the effect of surface tension at the nickel-vapor interface, and the effect of the interfacial tension, γWNi, at the tungsten surface, including a factor for the dihedral angle. Nickel does not wet tungsten completely. The contact angle at 1200 °C, as determined by scanning electronmicroscopy, is 35 °. Therefore, wetting is restricted to places of suitable geometry, especially grain boundaries. The activating effect of nickel on the sintering of 0.5 μm tungsten powder at 1000 °C is due to the enhancement of grain boundary self-diffusion in tungsten. At 1100 °C an additional contribution from rearrangement has to be considered. The behaviour of nickel at elevated temperatures on tungsten surfaces is qualitatively similar for flat tungsten surfaces and tungsten particles. In order to obtain a homogeneous nickel distribution in the tungsten compact, nickel has to be added by evaporation or in the form of chemical solution. Complete homogenization is not possible with tungsten-nickel powder mixes.
63 citations
TL;DR: In this article, aldaric (tartronic, tartaric, pentaric and hexaric) acids and deoxyaldaric acids were studied for the separation and identification of hydroxy dicarboxylic acids as open-chain trimethylsilyl derivatives.
Abstract: Gas chromatography - mass spectrometry offers a convenient method for the separation and identification of hydroxy dicarboxylic acids as open-chain trimethylsilyl (TMS) derivatives. Mass spectra were studied of aldaric (tartronic, tartaric, pentaric and hexaric) acids and deoxyaldaric (malic, 2-deoxypentaric, 2-deoxyhexaric, 3-deoxypentaric and 3-deoxyhexaric) acids. The different structural types can be readily identified from their characteristic spectra. The most prominent fragmentations involving the rupture of one bond are the loss of a siliconlinked methyl group and the formation of alfa-cleavage ions by carbon chain cleavage. The further decay is characterized by a number of significant rearrangements specific of TMS derivatives. Several of these can be classified as involving migration of a TMS group to an oxygen atom or migration of an ester OTMS group to a silicon atom. Concomitant loss of a stable molecule often provides a driving force. Prominent odd-electron ions are formed by a McLafferty-type rearrangement of a TMS group. The decomposition of several even-electron ions can be regarded as analogous to that rearrangement.
56 citations
TL;DR: In this article, the effects of typical transmission laboratory designs on measured reduction indices are investigated and the results imply that for lightweight walls mounting and laboratory design are of secondary importance for walls which are heavy compared to the test frame or flanking walls.
55 citations
TL;DR: In this article, the authors showed that the 4-O-methyl-D-glucuronic acid groups are randomly distributed in the xylan and the nonasaccharide and the lower homologues were isolated by chromatography on charcoal-Celite and by partition chromatography for ion exchange resins using aqueous ethanol.
TL;DR: Kinetic measurements in a stopped-flow apparatus of the direct reaction between the oxidized form of the oxidase and c2+ have been carried out to a limited extent, the most thorough study probably being that of Gibson et al.
TL;DR: In this article, the adsorption properties of polished iron, zinc, copper and aluminium samples have been compared with those of pre-exposed samples of these metals, showing that almost quantitative adaption of sulfur dioxide has been obtained on preexposed iron samples at r.h.
TL;DR: In this article, a McLafferty-type rearrangement of a trimethylsilyl group is demonstrated, and the positive charge and unpaired electron are extensively delocalized in the odd-electron rearrangements.
Abstract: A McLafferty-type rearrangement of a trimethylsilyl group is demonstrated. Abundant rearrangement ions are formed for trimethylsilyl derivatives of alpha,beta-dihydroxy carbonyl compounds. Data are given for a large number of hydroxy acids and hydroxy ketones including aldonic acids, aldaric acids, acyclic ketoses and hydroxy keto acids. A few branched lactones are also shown to rearrange.
The positive charge and the unpaired electron are extensively delocalized in the odd-electron rearrangement ions. Those substituents at the alpha-carbon atom which offer a favourable delocalization promote the rearrangement. Spectra of specifically methylated species reveal that migration over larger than six-membered rings occurs to some extent. An observed dependence of abundance on configuration is associated with steric strains in the transition state.
The rearrangement ions are of great diagnostic value in structural analysis. They are relatively more abundant at low electron energies and give rise to the base peak at 20 eV for many compounds. Ions produced by the competing conventional McLafferty rearrangement are less abundant.
TL;DR: In this paper, a finite element method was applied to actual microstructures to find out if the FEM can be used for analysis of the elastic properties of an isotropic two-phase composite material, WCCo.
TL;DR: In this article, the atomic-beam magnetic resonance method has been used in spin measurements on some neutron-deficient praseodymium and neodynium isotopes.
TL;DR: In this paper, the spin-polarized electron liquid is used in the density-functional method of Kohn and Sham to get spin-dependent, local one-body potentials and static dielectric properties.
TL;DR: In this paper, the 6, 7, and 8 p 2 P 3/2 levels of Cs 133 have been extended to the 9 and 10 p 2 p 3 /2 levels.
Abstract: Our previous level crossing measurements in the 6, 7, and 8 p 2 P 3/2 levels of Cs 133 have been extended to the 9 and 10 p 2 P 3/2 levels. For the magnetic dipole and the electric quadrupole interaction constants a and b we obtain ##IMG## [http://ej.iop.org/images/1402-4896/5/4-5/010/img1.gif] {figure 1} The natural lifetime of 9 p 2 P 3/2 was found to be 390 (30) ns. The previous analysis for the 6 and 7 p 2 P 3/2 levels is revised, taking new experimental data from this and other laboratories into account. This leads to a better consistency for the quadrupole moments Q for Cs 135 and Cs 137 as evaluated from the 6 and 7 p 2 P 3/2 levels. We obtain Q (Cs 135 ) = +0.052 (4) barn Q (Cs 137 ) = +0.053 (4) barn
TL;DR: In this article, the authors summarized recent results about the linear response properties and comments on the role of the non-locality of the self-energy in one-electron potentials.
Abstract: This paper summarizes recent results how to obtain approximate one-electron potentials describing exchange and correlation which depend on the local electron density. Following the lines given by Hohenberg, Kohn and Sham explicit results are given in two versions of the theory; one to describe ground state properties and one for excitation energies. The extension to spin polarized systems is discussed and some new results are presented. The paper also summarizes recent results about the linear response properties and comments on the role of the non-locality of the self-energy.
TL;DR: In this paper, a strong Jahn-Teller coupling between the impurity ion ground state and a vibrational mode of E symmetry was estimated for the optical absorption spectrum of Cr2+(3d4) in single crystals of ZnSe in the wave number region 500-4000 cm−1.
TL;DR: Differential ground state capture cross sections have been measured at 0° and Tp = 600 MeV for the reactions d (p, π + ) t, 3 He (p, π+ ) 4 He and 4 He ( p, ρ + ) 5 He as discussed by the authors.
TL;DR: The results of an experimental determination of the statistical properties of radiation from OH maser sources are reported and interpreted in this article, where the radiation is found to have Gaussian statistics with no deviations greater than 1%.
Abstract: The results of an experimental determination of the statistical properties of radiation from OH maser sources are reported and interpreted. The radiation is found to have Gaussian statistics with no deviations greater than 1%.
TL;DR: In this article, the locations of the 4f levels below the Fermi level are determined to be 2.4 eV and 2.1 eV, respectively, for Eu, Gd, and Yb.
Abstract: X-ray photoemission (XPS) measurements are reported on evaporated films of the rare earth metals Eu, Gd, and Yb. For comparison additional measurements are reported on Ba. The results provide an unambiguous determination of the 4f energy levels. In Yb the spin–orbit splitting is also clearly resolved. The locations of the 4f levels below the Fermi level are determined to be 2.1 eV for Eu, 7.7 eV for Gd, and 1.4 eV and 2.7 eV for Yb all with an error of ± 0.4 eV.
Es werden photoelektronenspektroskopische Messungen im Rontgenstrahlenbereich (XPS) fur aufgedampfte Schichten der Lanthaniden Eu, Gd und Yb sowie zum Vergleich auch fur Ba beschrieben. Die Ergebnisse ermoglichen eine eindeutige Bestimmung der 4f-Energieniveaus. Bei Yb ist zudem die Spin–Bahn-Aufspaltung deutlich aufgelost. Die Lage der 4f-Niveaus unterhalb des Ferminiveaus wurde bestimmt zu 2.1 eV fur Eu, 7,7 eV fur Gd und 1,4 und 2.7 eV fur Yb mit einem Fehler von ± 0.4 eV.
TL;DR: In this article, an energy transfer from the phenyl groups of surface active phenylundecanoate ions to naphthalene molecules has been studied under conditions such that the naphthane molecules have been solubilized by micelles of PDEs.
Abstract: — Excitation energy transfer from the phenyl groups of surface active phenylundecanoate ions to naphthalene molecules has been studied under conditions such that the naphthalene molecules have been solubilized by micelles of phenylundecanoate. From measurements of the naphthalene fluorescence intensity in solutions of varying surfactant concentration the critical micelle concentration has been determined as 0·0091 M. The product of the micellar aggregation number and the efficiency of energy transfer has been obtained as 75 from measurements of both the sensitized naphthalene fluorescence and the quenching of the phenylgroup fluorescence. In the evaluation of the experimental data it has been assumed that the partition of naphthalene between the micelles and the aqueous phase may be treated as a distribution equilibrium, and that the solubilized naphthalene molecules are partitioned among the micelles according to a Poisson distribution. With this model, the naphthalene fluorescence intensities may be accounted for over the whole range of surfactant concentrations.
At high naphthalene concentrations, emission from naphthalene excimers has been observed. The possibility of self-quenching via excimer formation is considered.
The experimental results point to a quantum efficiency near unity for the transfer of excitation energy from the phenyl groups of the surfactant ions that form a micelle to a single solubilized naphthalene molecule. The high efficiency suggests that the naphthalene molecule and the phenyl groups are present inside the micelles.
TL;DR: In this article, a sum-rule analysis was made for the 2 p 3 2, 1 f 5 2, 2 p 1 2 and 1 g 9 2 single-particle states and the results were compared with pairing theory.
TL;DR: In this paper, a recently developed capillary method has been employed to study tracer self-diffusion in liquid Na (102 to 284°C) and K (97 to 284 °C).
Abstract: A recently developed capillary method has been employed to study tracer self-diffusion in liquid Na (102 to 284°C) and K (97 to 284°C) The results may be expressed by D=D 0 exp(-Q/RT), where 103 D oNa = 086 (+009, −008) (cm2/sec), Q Na=222 ±008 (kcal/mole), 103 D OK = 076 (+006, −005), and Q K = 202 ± 007 The reexamination of electrotransport data for Rb (60 to 230°C) yielded the self-diffusion data 103 D ORb = 066 (+011, −009) and Q Rb = 198 ± 016 For liquid Li, the results of two investigations (195 to 440°C) have been combined, yielding 103 D OL1 = 144 (+ 007, −006) and Q L1 = 287 ± 007 For all four metals the empirical relation Q ⋍ 25 R[ttilde] is found to apply ([ttilde] being the mean exp temp) Also well obeyed is a nearly linear dependence on (T −072 T m) (where T m is the mp) Further, the self-diffusion coefficients at the respective melting points can all be expressed by , where M is atomic mass, V mol atomic volume and β = 011 Three alternative empirical
TL;DR: In this article, it is tentatively suggested that the spectrum showing the 1.4 eV edge is associated with another modification of lithium, which is not reconcilable with Ham's (1962) detailed band structure calculations.
Abstract: Lithium mirrors have been prepared by evaporation in ultra high vacuum onto cooled fused quartz and sapphire substrates; their optical properties were determined in situ by ellipsometry. Films deposited on sapphire show an absorption edge, uncorrected for possible broadening effects, at 2.4 eV at 125 K. The position of the edge is weakly temperature-dependent. The optical mass is 1.33. Lithium mirrors deposited on fused quartz have properties varying with time after deposition. Soon after evaporation the edge at 298 K appears at 1.4 eV and the optical masa is 1.7. The films then show variable properties but eventually assume a stable behaviour similar to that obtained with films deposited on sapphire. It is tentatively suggested that the spectrum showing the 1.4 eV edge is associated with another modification of lithium. The optical data for b.c.c. lithium are not reconcilable with Ham's (1962) detailed band structure calculations. If we assume that the proposed value for the energy gap at the N ...
TL;DR: In this article, the evolution in time of explosively unstable systems under the influence of time-dependent dissipative and nonlinear coupling effects is studied, and generalized criteria for instability as well as new mode solutions are constructed by introducing a suitable transformation in time.
Abstract: The present study concerns the evolution in time of explosively unstable systems under the influence of time-dependent dissipative and nonlinear coupling effects. Generalized criteria for instability as well as new mode solutions are constructed by introducing a suitable transformation in time.
TL;DR: In this article, an analysis of the magnetic and electric hyperfine structure has been performed for the 6p3 configuration of 209Bi by use of an effective hyperfine Hamiltonian, and the experimental mean values of r-3 exist for the orbital, spin-dipole and spin terms of the Hamiltonian.
Abstract: An analysis of the magnetic and electric hyperfine structure has been performed for the 6p3 configuration of 209Bi by use of an effective hyperfine structure Hamiltonian. For the magnetic hyperfine structure, experimental mean values of r-3 exist for the orbital, spin-dipole and spin terms of the Hamiltonian. Theoretical mean values of r-3 obtained from relativistic self-consistent-field (SCF) wavefunctions are in good agreement with the experimental orbital and spin-dipole values of r-3, while relativistic effects can only explain about 50% of the experimental spin part. This discrepancy is mainly due to core polarization, which has been estimated by use of non-relativistic unrestricted SCF wavefunctions. The core polarization contribution has been corrected for relativistic effects using correction factors obtained from a comparison between relativistic and non-relativistic restricted SCF wavefunctions. Most of the spin part of the hyperfine interaction can be explained in this way. By use of hyperfine radial integrals obtained from relativistic SCF wavefunctions the quadrupole and octupole moments have been evaluated with the result: Q = -0.46 b. (Sternheimer uncorrected) and Ω = 0.62(8) n.m.b. respectively.