Volume 35, Issue 6

A Canonical Transformation as a Proposal of the Solution of a Functional Equation Starting with a functional equation of the New Tamm-Dancoff procedure for electronic states of defects in solids we describe an attempt to transform this equation. The aim is to extract a one-particle equation as a projection which is a good approximation for the case of a defect. The transformation usetii s a simple approach to more general canonical transformations leading to inequivalent representations of the many-body problem. It is compared with the elimination procedure given in a first paper [1] which treated the manj-electron problem occuring with the storage of hydrogen in metals

We present a unified formulation of the interaction of electrons with the electromagnetic field in heavy ion collisions, based on quantized interacting fields. This reduces the effort in treating many-electron systems substantially, as compared with the usual S-matrix theory. Both formalisms are shown to be equivalent. The simplification achieved by our new approach is demonstrated in detail for the example of quasi-molecular radiation

Incoherent, inelastic neutron spectra of TaS 2 (NH 3 ), TaS 2 (NH 3 ) 1-χ - and TaS 2 (NH 3 ) 1/3 (H 2 O) 2/3 were measured in the range 250 cm -1 → 1600 cm -1 . The data suggest the presence of NH 4 + cations and are in agreement with an ionic structure model proposed for these compounds

The empirical linear correlations of Rydberg term values [S. P. McGlynn, S. Chattopadhyay, P. Hochmann, and H.-t. Wang**, are discussed in a first-order perturbation-theoretic format. In the second-order, quadratic dependencies are expected. The theoretical development assumes that the gross features of interatomic and intermolecular Rydberg term value variations can be discerned using a one-electron model; that a molecule XS, X being the Rydberg chromophore and S the substituent, can be partitioned so that the affairs of the optical electron are dominated by its interactions with the chromophoric segment; and that the charge distributions, whether of X or S, can be expanded in ways which permit evaluation of the effects of small variations in either X or S on Rydberg term values. The development is restricted to Class 1 molecules: Molecules which possess a common S and variable X, but where all X must be of similar electronic structure e.g., X = F, Cl, Br, I). A variety of correlative algorithms is discussed, and the intergroup transferability of parameters is elaborated in terms of the properties of "average chromophores"

The scattering of cold neutrons (λ = 1 nm) with amorphous Fe 80 11 B 20 yields a strong contribution at small q = (0.07(nm) -1 ≦ q ≦ 2.4(nm) -1 ) arising from two kinds of defects of different size: i) Local defects with an extent of about 1.5 nm, ii) Extended defects with an extent of about 40 to 60 nm, which are interpreted as quasi-dislocations in the amorphous material

Simultaneous grain boundary-, surface- and lattice diffusion in hypothetical thin film couples of miscible components was computer simulated. On this basis the diffusion into fixed and moving grain boundaries is discussed with respect to the determination of diffusivities by depth profiling methods. The data evaluated from the synthesised depth profiles according to Whipple-Le Claire as well as to Gilmer and Farrell were compared with the diffusivities used for the computation. Agreement was found for systems with a fixed grain boundary network. Moving grain boundaries, however, may cause errors of an order of magnitude towards lower grain boundary diffusivities

A theoretical treatment is presented for the determination of the screw sense of a cholesteric substance in a Grandjean-Cano-wedge by observing the sample in a polarizing microscope. For comparison some experimental measurements are given

The dipole moment of 1,1-bis-p-chlorophenylethylene, 1,1-bis-p-bromophenylethylene, 1,1-bis-pmethoxy, -ethoxy, -isopropoxy-phenyl-ethylene, 1,1,4,4-tetrakis-p-methoxy, -ethoxy, isopropoxyphenylbuta- l,3dienes was measured and compared with the calculated value. The mesomeric moment was estimated and found to decrease in the case of the ethylenes with the increase in volume of the substituted group. For the butadienes, the mesomeric moments compensate each other. Investigations of the dielectric relaxation times of the ethylenes showed that the orientation of the -OCH 3 group in the 1,1-bis-p-methoxy-phenylethylene is hindered to a large extent. The orientation of the -OC 2 H 5 and -OC 3 H 7 groups in the corresponding molecules are restricted due to steric hindrance

The l a method for an atom or molecule is transformed into an all-electron pseudopotential formalism. The equations of the X ɑ method are exactly transformed into pseudo-orbital equations and the resulting pseudopotentials are replaced by simple density-dependent potentials derived from Thomas-Fermi model. It is shown that the new formalism satisfies the virial theorem. As the first application it is shown that the model explains the shell-structure of atoms by the property that the pseudo-orbitals for the (ns), (np), (nd) etc. electrons are, in a very good approximation, the solutions of the same equation and have their maxima at the same point thereby creating the peaks in the radial density characterizing the shell structure

DNA has been irradiated in aqueous solutions with 16 MeV electron pulses (duration: 50- 100 ns). In the presence of p-nitroacetophenone (PNAP) the light scattering intensity (LSI) increased after the pulse in Ar- and 02-saturated solutions indicating intermolecular crosslinking. The LSI increase was greatest in Ar-sat. solutions containing t-butanol (1 mol/1). In the absence of PNAP and t-butanol DNA was degraded as indicated by a decrease of LSI. The results contribute to the understanding of radiation-induced reactions, DNA undergoes in the presence of sensitizers of high electron affinity

Comparison of Hel and Hell photoelectron (PE) spectra of pyridine-N-oxide enables the completion of the assignment of its electronic structure

Direction and angle of molecular tilt in an ordered multilayer system of dipalmitoyl lecithin and water were directly determined by X-ray diffraction as a function of temperature in the gel phase with ca. 20 wt. % of water

The free induction decay of 23 Na of hydrated zeolite Na-Y has been measured at 295 K. Its intensity as a function of the length of the exiting pulse proves that a whole spectrum of 4 sodium ions per cage is observed. By ion exchange it is found that only the sodium ions in the sixmembered rings (site S2) contribute to the observable NMR-signal

We have measured the Seebeck coefficient of the Sn 0.74 - Pb 0.26 liquid alloy, in the temperature range 190° C- 700° C. The results were compared with those predicted by the Faber-Ziman theory

A review of hollow cathode discharges for gas (metal vapour) lasers is given. Particular attention is paid to the arc free discharge region and to the possibility of increasing the intensity of the ionic spectrum of the discharges