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M. W. Thompson London: Cambridge University Press. 1969 Pp. viii + 384. Price £6 Prof. Thompson has written a book in which the ideas and material are presented at two quite distinct levels of scientific sophistication. In the first quarter of the book he discusses the nature of point and extended defects in crystals…
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiimide reduction of porphyrinsHoward W. Whitlock Jr., R. Hanauer, M. Y. Oester, and B. K. BowerCite this: J. Am. Chem. Soc. 1969, 91, 26, 7485–7489Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https:/…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic analysis of thermogravimetric dataJohn Henry. Sharp and Sally A. WentworthCite this: Anal. Chem. 1969, 41, 14, 2060–2062Publication Date (Print):December 1, 1969Publication History Published online1 May 2002Published inissue 1 December 1969https://pubs.acs.org/doi/10…
A method for determining the position of dislocation lines accurately from dislocation images is reported and applied to the case of measuring the separation of partial dislocations. A theoretical analysis of the method is given, and the predictions verified by many-beam computed image profiles. The separation of part…
Abstract Die Darstellung einer Reihe von Porphyrin‐Metall‐Komplexen wird beschrieben. Unter Berücksichtigung von bekanntem und neuem Tatsachenmaterial wird eine Deutung der unterschiedlichen Elektronenspektren der Porphyrinkomplexe gegeben. Ausgehend von Salzen ms ‐tetrasubstituierter Porphine, die als Alloporphin‐Der…
We present electron diffraction data from amorphous silicon which cannot be reconciled with the intensity profiles derived from small-crystallite models based on the diamond structure. Our diffraction patterns do reveal a pronounced low-angle scattering which anneals out on progressive heating and is indicative of act…
A new energy parameter ${\mathcal{E}}_{d}$ is introduced to describe dispersion of the electronic dielectric constant. This dispersion energy is found to obey an extraordinarily simple empirical relation in the more than 50 ionic and covalent crystals for which reliable refractive-index dispersion data are available.…
By measuring changes in the dielectric constant of a 1.75:1 cholesteryl chloride–cholesteryl myristate (CM) mixture in the presence of magnetic fields H up to 10 kG, the orientation of the molecular and helical axes with respect to the field direction can be deduced, and the possibility of a dependence of the alignmen…
X-Ray diffraction has shown the existence of a low temperature tetragonal phase of (NH 4 ) 2 TeBr 6 having space group P4/mnc(D 4h 6 ) with a = 7.501, c = 10.765 Å.
A, B , and C bands with peaks at about 4910, 4220, and 3990 Å (mean values for split subbands at 77°K), respectively, were found in the excitation or reflection spectra of visible region of ZnS:Pb (zinc-blende) phosphors. These bands were analyzed by means of Sugano's molecular-orbital theory and identified unambiguou…
A quasiequilibrium treatment of heterogeneous reactions is used to compute the rates of evaporation (desorption) of volatile species formed in the reaction of gaseous O2 with solid tungsten, molybdenum, and graphite under conditions of low pressure and high temperature. The results are compared with existing mass–spec…
Structural phase transitions in perovskite crystals involving displacements of the oxygen octahedra due to the condensation of linear combinations of the triply degenerate ${\ensuremath{\Gamma}}_{25}$ modes at the $R$ corner of the Brillouin zone are discussed with the help of a model Hamiltonian. These distortions ar…
The vaporization of uranium mononitride UN has been investigated by the Knudsen effusion technique in combination with a mass spectrometer. The vaporization occurs incongruently by preferential loss of nitrogen forming the two-phase system nitrogen-saturated liquid uranium–uranium-saturated nonstoichiometric uranium m…