Benz[c]octalen

An expedient new synthesis of benzo[c]octalene starting from the Diels-Alder adduct of benzocyclobutadiene to 7,8-dimethylenecycloocta-1,3,5-triene is described. This octalene derivative, in solution, exists as an equilibrating mixture of the double bond isomers (2) and (3) whereas in its crystalline state only the isomer (2) is present.     

Reduktionsverfahren für Differenzengleichungen bei Randwertaufgaben II

Summary In a recent paper [11], two of the authors investigated a fast reduction method for solving difference equations which approximate certain boundary value problems for Poisson's equation. In this second paper, we prove the numerical stability of the reduction method, and also report on further developments of the method. For the general case, the provided bounds for the numerical errors behave roughly like the condition numberO(n ²) of the linear system; for more realistic model problems estimates of order less thanO(n) are obtained (n ^–1=h=mesh width). The number of operations required for the reduction method isO(n ² ), for the usual five-point difference formula, as well as for the common nine-point formula with discretization error of orderh ⁴.     

Einige Probleme im Zusammenhang mit der direkten Bestimmung der spezifischen Wärmen mittels Differential Scanning-Kalorimetrie

The relation between sample mass andDSC-amplitude was investigated under various experimental conditions for vitreous quartz, both as discs and powders. Contrary to other authors³ proportionality has been found up to the highest masses (75 mg) used. A statistical analysis of the data indicates that the accuracy of directC _p-measurements byDSC can be increased by determining the blank value by extrapolation of the amplitudes for several masses to zero mass instead of using the usual procedure, which involves a run with the empty pans. The overall error ofC _p due to instrument errors is estimated not to exceed 2%.     

Laser spectroscopic determination of the 50V quadrupole moment

Using the method of atomic-beam magnetic resonance, detected by laser-induced resonance fluorescence (ABMR-LIRF), the atomic ground-state hyperfine intervals of ⁵⁰V were precisely measured. A quadrupole moment ratio $\text{Q(}{}^{50}\text{V}\text{) / (}{}^{51}\text{V}\text{= ?4.03(3)}$ is obtained which results in $\text{Q(}{}^{50}\text{V}\text{) = +0.21(4)}\text{b}$.     

Einfluß elektrischer Felder auf die Eigenabsorptionskante fester Körper

This paper realizes an idea ofRedfield in a general and quantitative manner: Charged point defects produce local electric fields in a crystal which cause a change in the absorption-constant compared with the absorption-constant of an undisturbed crystal (Franz-Keldysh-effect). Thus one gets a tail in the absorption constant decreasing from the ideal intrinsic absorption edge towards longer wave-lengths. Applying an external fieldF one finds an additional, frequency-dependent absorptionconstantΔα. Its magnitude and spectral distribution depend on the concentration of defects. For external fields smaller than the internal onesΔα∝ F ² holds at all frequencies. The results are compared with those found byFranz.     

Makrocyclische,luftbeständige acht- und sechselektronenliganden für übergangsmetalle

The synthesis of five eight-electron-ligands, two six-electron-ligands and one four-electron-ligand for transition metals is described. These heterocycles contain in each case arsenic and sulfur as heteroatoms, and additionally oxygen in one case.