A field theoretical approach to calculate electronic Born-Oppenheimer coupling terms

In this paper we suggest to consider the spatial distribution of the Born-Oppenheimer nonadiabatic coupling terms as fields which are created by sources, located at degeneracy points, and which can be derived using the ordinary mathematical tools of field theory. It is shown that the curl-divergence equations as formed within a given Hilbert space [M. Baer, Chem. Phys. Lett. 35, 112 (1975)] can be converted into a set of inhomogeneous coupled Poisson equations which are solved for a given set of boundary conditions. The method is applied to the three-state Hilbert subspace of the H(3) system. The numerical results are compared with ab initio calculations for which a very encouraging fit is found.     

Effect of the morphology of polyethylene glycol esters on the distribution of C1–C4 carboxylic acids in the gas phase-sorbent system

The effect of the morphology of polymer films on the distribution of volatile C₁–C₄ carboxylic acids in the sorbent-gas system is discussed. The efficiency of sorption of vapors of formic, acetic, propionic, and butyric acids on films of polyethylene glycol esters of various structures formed on the electrodes of a piezoquartz resonator by means of static evaporation of a drop and immersion of the resonator into a sorbent solution is evaluated.     

Koordinationschemie von Dinitroresorcin mit Kupfer-, Kobalt-, Nickel-, Eisen- und Zinksalzen

The reactions of the bidentate dinitrosoresorcinol (DNR) with copper, cobalt, nickel, iron and zinc salts were investigated. This ligand was found to react with these metal salts in aqueous media where hydrogen ion was confirmed to be liberated except in case of iron. The solid complexes were prepared in alcoholic media. Chemical analyses, magnetic and spectral data were compatible to determine the structure of these complexes and their mode of chelation.

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Mit 2 Abbildungen     

Crystallization impedance in the case of D.C. superposition

An expression for the impedance frequency dependence in the case of d.c. superposition has been derived and analyzed for the crystallization process of metals taking into account the two-dimensional diffusion of ions in solution and the surface diffusion of adatoms and using the simplest surface model with parallel step lines. It is shown that in the general case it is impossible to present the crystallization impedance as the sum of the surface diffusion impedance and the Warburg impedance. It has been found that in the case of anode polarization an unusual effect of the impedance increasing with agitation intensity takes place which is typical of this mechanism. Possible methods for determination of the model parameters from impedance measurements are discussed. The authors suggest an iteration procedure which permits to determine all the parameters of the model under consideration including the surface diffusion coefficient of adatoms and the spacing between the growth step lines.     

Microstructure determination of poly-(1,3-pentadiene) by a combination of infrared, 60-MHz NMR, 300-MHz NMR,and X-ray diffraction spectroscopy

A quantitative procedure has been developed for characterizing the complete microstructure of polymers of 1,3-pentadiene, including the tacticity of any crystalline component. This can be accomplished by a combination of infrared spectroscopy, X-ray crystallinity, and 300-MHz NMR spectroscopy. A series of high structural purity polymers were synthesized with a series of previously unreported mixed microstructures. These samples were characterized by using the three techniques mentioned, including the previously unreported 300-MHz NMR data. With those results a 60-MHz NMR/IR method of spectroscopy was developed to determine the composition of poly(1,3-pentadiene)s in terms of percent cis-1,2-, cis-1,4-, trans-1,4-, and 3,4-pentadiene units.     

Studies in the furan series

A study was made of certain transformations of the bicyclic compounds of the fur an series synthesized from 3,4-bis(chloromethyl)furan, N-butyl-4H, 6H-furo [3,4-c]pyrrole and 4H,6H-thieno[3,4-c]furan. On the basis of the same dichloride, 3,4-dimethyl furan and furan-3,4-dialdehyde were synthesized.For part XLVI, see [10].     

Effect of the homogeneity of the column set on the performance of a simulated moving bed unit. I. Theory

Although it is impossible to manufacture identical columns for use in a simulated moving bed (SMB) process, theoretical studies assume that all the columns in an SMB unit have identical characteristics. In practice, calculations in modeling and optimization studies are made with the average values of each column parameter set. In this report, the effects on SMB process performance caused by column-to-column fluctuations of the parameters are discussed. As a first step, we show how the differences in porosity of the columns may be taken into account with a revised set of separation conditions. Reductions in the purity of the extract and the raffinate streams are quantitatively related to the column-to-column fluctuations of the retention times of the two components arising from these porosity differences. For the sake of simplicity, the discussion first addresses the case of a four-column SMB operating under linear conditions. Then, the scope is extended to the cases of SMB units incorporating several columns in each section and to SMB units operating under nonlinear conditions.     

Separation and identification of organic and organometallic compounds by use of a liquid chromatography-particle beam-glow discharge mass spectrometry combination

Evaluation of the particle beam glow discharge mass spectrometry (PB-GDMS) system as a detector for liquid chromatography (LC) is described for the analysis of polycyclic aromatic hydrocarbons, steroids, selenoamino acids, and alkyllead compounds. A particle beam interface is used to introduce analyte species from the LC into a glow discharge source for subsequent vaporization and ionization. Mass spectra display classic EI fragmentation patterns for the organic compounds, as well as elemental and molecular information for the organometallic compounds. Chromatographic separations display good temporal correlation between UV and PB-GDMS detection modes. Detection limits for Pb in lead nitrate, triethyllead, and triphenyllead fall in the sub-ppb (ng) range.     

Perturbation approach for frequency shifts in IR spectra of molecular clusters

A second order perturbation approach for the evaluation of the splitting and shifting of the infrared vibrational bands of molecular clusters, based on early publications of Buckingham, is presented. The Hamiltonian of the system comprises harmonic- and anharmonic intramolecular vibration terms, as well as the intermolecular potential. The anharmonic contributions of the intramolecular force field and the intermolecular potential are treated as a perturbation. In order to extend the applicability of the approach to homogeneous molecular clusters, the formalism of degenerate perturbation theory is employed. The new approach is applied to methanol clusters from dimer to hexamer for calculating the frequency shifts of the OH stretching mode (ω₁=3681.5 cm^?1), the CH₃ rocking mode (ω₇=1074.5 cm^?1), and the CO stretching mode (ω₈=1033.5 cm^?1). The numerical results compare favourably with experimental and previous theoretical data (except for ω₁), but with a tendency to overestimate the shifts.     

Mass spectra of permethylates of spirostanol tetraosides

The design of the new MKh 1310 mass spectrometer with double focusing permits the recording of the spectra of sparingly volatile natural compounds with molecular weights of up to 1700 and, in particular, the permethylates and peracetates of spirostanol and furostanol saponins. The results are given of an investigation of the mass spectra of five spirostanol tetraosides in the form of their permethylates. The spectra contain the peaks of the molecular ions and of the products of their decomposition at the glycosidic bonds. The most important feature of the spectra is the fragmentation of the skeletons of the terminal saccharide residues starting directly from M⁺ in directions close to the directions of decomposition of the nonreducing unit of permethylates of oligosaccharides. The origin of the ions (M -191)⁺, (M - 175)⁺, (M - 162)⁺, (M - 147)⁺, (M - 131)⁺, (M - 118)⁺, and (M - 102)⁺ arising this way have been confirmed by measurements of their elementary compositions.