Materials Literature
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Extensive and accurate viscosity values for molten B 2 O 3 are reported over the continuous range from 20 poises (at 1400°C) to 10 10 poises (at 318°C). The measurements were made with a wide‐range rotating‐cylinder viscometer. The melts were pretreated by bubbling superdry nitrogen through them to ensure a minimum wa…
The symmetry properties of the third-rank tensor β which comprises the set of coefficients of quadratic terms in the expansion of the induced-dipole moment in the electric field are investigated, and the various linear combinations belonging to the irreducible representations are tabulated for the important molecular…
Previous investigators have shown that natural chromium-bearing spinel solid solutions adhere closely to the general formula (Mg, Fe ++ ) (Cr, Al, Fe +++ ) 2 O 4 and may therefore be graphically portrayed in a triangular prism, the length of which represents the ratios MgO/FeO, and the cross section the relative propo…
The variation with magnetic field of the surface reactance of gallium single crystals at 2 Mc/sec has been investigated at helium temperatures and for fields up to 1500 G. The changes observed in the surface reactance depend in a very complicated way upon magnetic field, and correspond to variations of nearly 100% in…
At very low temperatures the thermal conductivity of insulating crystals containing point defects is limited by boundary relaxation processes and by Rayleigh scattering of long-wavelength phonons: at higher temperatures resonant modifications of Rayleigh scattering and phonon-phonon scattering dominate. Experiments by…
A theory of acoustic-mode scattering has been formulated within the tight-binding approximation of band theory, and has been applied to narrow-band semiconduction in organic molecular crystals. The latter problem has been treated previously only in terms of phenomenological scattering parameters. The interaction const…
The paramagnetic susceptibility and magnetic specific heat of the complex salt [${\mathrm{Cr}}_{3}$${(\mathrm{C}{\mathrm{H}}_{3}\mathrm{C}\mathrm{O}\mathrm{O})}_{6}$ ${(\mathrm{OH})}_{2}$]-Cl\ifmmode\cdot\else\textperiodcentered\fi{}8${\mathrm{H}}_{2}$O are examined theoretically in the light of recently obtained know…
This paper discusses the differential cross section for pair production by electron scattering off an arbitrary fixed potential (trident). This cross section assumes that the three outcoming electrons' energies are to be measured. A modified version of the Monte Carlo procedures is used to obtain the cross section. Th…
Abstract In an extension of studies on the exchange of meso-hydrogen in porphyrins and reduced porphyrins (R. Bonnett & G.F. Stephenson, unpublished results) the nuclear magnetic resonance spectra of natural corrinoid derivatives have been investigated. Since it was hoped to observe a signal due to the CIO proton…
Abstract Corroles have been prepared by the irradiation of basic solutions of 1,19-dideoxybiladienes-ac. Some physical and chemical properties of corroles are described including the formation of the aromatic corrole anions. Cyclization of the nickel derivative of a 1,19 dimethyl-1,19- dideoxybiladiene-ac gives a macr…
Abstract This paper is a report on the structure determination by X-ray analysis of the nickel(II)-1,8,8,13,13-pentamethyl-5-cyano-trans-corrin chloride, the synthesis of which is described by Eschenmoser et al. in the preceding paper. There are two reasons that led us to carry out this work. In the first place, it wa…
Abstract In 1963 a description of the work in progress at the laboratories of the E.T.H. towards the synthesis of corrins was presented (Eschenmoser 1963). At that time, we were able to report the synthesis of the analytically and spectroscopically well defined crystalline nickel complex I; however, the ultimate probl…
Received 18 October 1965DOI:https://doi.org/10.1103/PhysRevLett.15.784©1965 American Physical Society
The infrared-absorption spectra of a selection of aluminum-doped and nominally boron-doped semiconducting synthetic diamonds have been measured from 1 to 10 \ensuremath{\mu} at temperatures near 100\ifmmode^\circ\else\textdegree\fi{} and 300\ifmmode^\circ\else\textdegree\fi{}K. These spectra are shown to be very simil…
Alignment by electric or magnetic fields of molecules comprising the liquid crystalline phase of a nematogenic material is manifested in proton magnetic resonance spectroscopy by the appearance of nuclear dipole-dipole fine structure. Additionally, much larger splittings ranging up to 300 G are observed in the deuteri…
Using a recently proposed procedure, the localized molecular orbitals are determined for minimal-basis-set LCAO—SCF wavefunctions of the molecules LiH, BH, NH, FH, Li2, B2, Be2, N2, F2, CO, BF, LiF. In all cases, well-defined inner-shell, lone-pair, and bond orbitals are found. They exhibit a considerable degree of tr…
The defect distribution in an ionic crystal is calculated for both pure crystals and crystals containing divalent cationic impurities. By taking the electrostatic energy into account explicitly, it is shown that bulk electrical neutrality and space-charge regions surrounding the vacancy sources are an inherent aspect…
A nuclear-magnetic-resonance method is explored, which effectively attenuates the dipolar interaction in solids. The experimental technique corresponds to the observation of a free-induction decay in a frame of reference rotating with the frequency of an applied rf field. When the amplitude ${H}_{1}$ of this field is…
Distribution of magnesium and strontium was determined between waters and calcites secreted by the oyster species Crassostrea virginica and C. rhizophorae in natural habitats at eight localities, from Maine to Puerto Rico. The concentration of strontium in the calcite shells increases with increasing temperature in th…
The Wagner equation for the isothermal oxidation of metals is re-established. One of the assumptions used in deriving the equation is removed.