The use of substitution groups to derive thermodynamical relations between the material constants of piezoelectric materials

It is shown how substitution groups can be used to derive relations between the material constants of an anisotropic homogeneous piezoelectric medium. The structure of these relations is explained by means of a general record and independent systems are found, the existence of which has a clear physical interpretation. The concept of substitution group is generalized and some important thermodynamic substitution groups are derived; the method can be applied without substantial changes to an arbitrary type of anisotropic homogeneous medium.     

Relativistic generalization of dynamic equation for Jost function

A system of dynamic equations for the simultaneous determination of the scattering amplitude and the relativistic Jost function is derived from the Mandelstam representation and the unitarity condition. The relativistic generalization of the de Alfaro, Regge and Rossetti dynamic equation for the Jost function is given.     

Beitrag zur Theorie der Temperaturfaktoren des Vibrationsspektrum der Moleküle

An attempt is made to derive general expressions for temperature factors to which the intensities of the absorption bands of the vibrational spectrum of molecules are directly proportional. For the sake of simplicity, the process of induced emission is neglected. The temperature factor for the line corresponding to the transition (v ₁,v ₂,...,v _s ) (v ₁+p ₁,v ₂+P ₂,...,v _s +p _s ) with multiplicity ₁,₂, ..., is given by expression (3) and the temperature factor for the band is given by expression (4). These relations were used to calculate the ratios of the temperature factors for the case of double and triple degenerate energy levels and satisfactory agreement with the experimental results studied in paper [2] was obtained.

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Abschließend möchte ich Herrn Ing. A. Vako für die Veranlassung zu dieser Arbeit bestens danken.     

Dislocation stress fields in α-Fe

The stress components based on anisotropic elasticity are found for edge and screw dislocations in α-Fe. The method of Eshelby, Read and Shockley is used.     

Double quantum transitions in free radicals

The observation of double quantum transitions on three kinds of free radicals (DPPH, DPANO, ultramarine) at temperatures of liquid nitrogen is described. Signals having an absorption and emission character were observed in the 12-5 MHz–18 MHz frequency band in the direction parallel to the external magnetic fieldH ₀ and their dependence on different parameters was studied.Bloch equations were solved for two mutually perpendicular high-frequency fields and expressions were found for the components of dynamic susceptibility in theH ₀ direction. The experiments agree with theory.The possibility of using double quantum transitions for measuring relaxation times is discussed.

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(DPPH, DPANO, ) . 12,5MHz–18MHz H ₀, ; . H ₀. . .

     

Improved synthesis of arachno-6,9-C2B8H14 and its halogenation under electrophilic conditions

A convenient synthesis of arachno-6,9-C₂B₈H₁₄, based on the reduction of nido-5,6-C₂B₈H₁₂ with sodium tetrahydroborate, is reported. Electrophilic halogenation of the former carborane produced a series of 1-X-6,9-C₂B₈H₁₃ (X = Cl, Br and I) derivatives whose constitution was established on the basis of their ¹H and ¹¹B NMR spectra.