Eine Röntgenkleinwinkelanalyse von Polyacrylnitril-Fasern

Measurements of the equatorial X-ray small-angle scattering are reported for 9 polyacrylnitrile fibers. They are evaluated according to Porod's theory. Data on void fraction and inner surface are obtained. With several samples, a Gumier-evaluation of the inner portion is possible, agreement is satisfactory. An attempt is made to interpret the results obtained with the help of a cyhndric model.     

Anisotropic electron-phonon scattering in metals

A previously published general theory for the effects of electron-phonon scattering in metals involves all relevant anisotropies and permits a virtually exact solution of the Boltzmann equation. The electron-phonon interaction is represented by a few Wannier matrix elements that are adjusted to experimental data. Calculations of the electron lifetime and the mass enhancement in copper show good average agreement with the experiments. For reproducing the exact anisotropies further non-diagonal elements have to be considered. The calculated temperature dependence of the Hall effect agrees qualitatively with the observations and reveals the local maximum found for both pure copper and dilute alloys.     

Atmosph?rische Luft

Ohne Zusammenfassung     

Determination of the individual spin-lattice relaxation rates between the spin levels of phosphorescent triplet-state molecules

It is shown how one can determine the individual spir-lattice relaxation rates of a phosphorescent triplet-stale molecule from analysis of the recovery curve in the phosphorescence intensity upon a microwave sweep through one of the zero-field transitions.     

Non-Maxwellian Electron Velocity Distribution Resulting from Electron-SF6 Attachment Collisions

A model reaction system is considered consisting of a heat bath of argon atoms (c) and small concentrations of SF₆-molecules (m) and electrons (e) (number densities: n_e ? n_m ? n_c). Within the model the time behaviour of the electron velocity distribution function is studied under the influence of elastic electron-argon collisions and electron SF₆ attachment collisions. On the basis of the distribution function time-dependent macroscopic quantities (kinetic electron temperature. nonequilibrium rate constant of the attachment reaction) are calculated.