bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational levels and Franck–Condon factors of diatomic molecules via Morse potentials in a box
Authors: Ley‐Koo E. , Mateos‐Cortés S. , Villa‐Torres G. 
Published: December 2004

AbstractThis work deals with two shortcomings in the use of Morse potentials to describe energy spectra and transitions of diatomic molecules: (1) Morse's well‐known “exact” solution for purely vibrational states includes the unphysical region – ∞ < r < 0 of the internuclear separation, and (2) Franck‐Condon factors are evaluated in harmonic and anharmonic approximations to the Morse potentials. The method of confining the molecule in a spherical box is developed to obtain (1) purely vibrational energy spectra and eigenvectors of Morse potentials in the physical region 0 ⩽ r < ∞, and (2) the corresponding Franck‐Condon factors without any additional approximations. The method is applied to Li2, N2, CN, and CO molecules. © 1995 John Wiley & Sons, Inc.
Density functional theory including Van Der Waals forces
Authors: Lundqvist B. I. , Andersson Y. , Shao H. , Chan S. , Langreth D. C. 
Published: December 2004

AbstractA progress report is given of an extension of the density functional formalism to include long‐range interactions such as van der Waals or dispersion forces. This is done by proving a general expression for the so‐called exchange‐correlation energy to contain and to describe such interactions just as well as any other treatment. The proper long‐range forms of the interactions are derived explicitly in the cases of two neutral atoms, an atom outside a metal surface, and two parallel metal surfaces. The long‐standing problem of treating the attractive and repulsive forces on the same footing in this way gets a solution. For practical calculations, an approximate form, based on an analysis in the weakly inhomogeneous limit and on a limiting form of the three‐point function given by Rapcewicz and Ashcroft, is proposed and applied to some prototype cases. © 1995 John Wiley & Sons, Inc.
Subtle energies in density functional theory: Correlation and molecular dissociation
Authors: March N. H. 
Published: December 2004

AbstractIn nonrelativistic theory, heavy atoms with atomic number Z have binding energies that can be analyzed into a sum of decreasing terms: (i) the Hartree energy αZ7/3, (ii) a “boundary correction” αZ2 due to Scott, and (iii) exchange energy in the Dirac‐Slater approximation αZ5/3. Correlation varies grossly linearly with Z and a density functional interpretation is proposed. Generalization to diatomic molecules is then considered, the total overlap population being now an important ingredient. Both heteronuclear and homonuclear molecules are treated. Attention is then focused on the molecular dissociation energy D: a further “subtle” quantity for density functional theory because of Teller's theorem. Following the proposal of Mucci and March, in light molecules with N electrons, D/N2 is connected with the von Weizsäcker inhomogeneity kinetic energy Tw; this motivates a brief discussion of scaling properties of this latter quantity. Generalizing the treatment of atomic energies outlined above, the 1/6 power law relating D/N2 with Tar is obtained. Finally, for the valence electrons only in alkali metal clusters, D/N is related to Tw using pseudopotential calculations. © 1995 John Wiley & Sons, Inc.
Electron correlation: Keeping close to an orbital description
Authors: Hedin Lars 
Published: December 2004

AbstractThis article deals with excited‐state properties and spectroscopies which probe them. We argue that the orbitals obtained in local density theory form an excellent basis for discussing excited states and that the self‐energy operator (or optical potential) associated with one‐electron‐type excited states is closely diagonal in such a basis. This diagonality often leads to considerable simplifications. We also discuss the reasons for the successes of the “GW‐approximation” for the optical potential in predicting excited states. We further discuss a recent approach to calculate spectroscopic data. In particular, we present explicit results of this approach to photoelectron emission. The approach treats correlations within the target exactly but neglects some terms in the coupling between target and probe electron (= the photoemitted electron). This leads to closed expressions which exhibit a number of qualitative features. One is the cancellation of intrinsic and extrinsic losses at threshold excitation. Another is the broadening of the quasi‐particles; we have energy‐broadening for the occupied states but broadening through decaying wave functions for unoccupied states. © 1995 John Wiley & Sons, Inc.
Integral–geometrical consideration of density matrices
Authors: Zapol Boris P. 
Published: December 2004

AbstractThe ensemble N‐representability problem for the k‐th order reduced density matrix (k‐RDM) as well as the problem of reconstruction of the N‐particle system density matrices (N‐DM) from a given k‐RDM are studied. The spatial parts of the k‐RDM expansion in terms of spin tensorial operators Θ are represented using particular values (at specially chosen ) of the Radon transform of the N‐DM spatial parts (or their sums) 𝒟Nλ(x′ | x″) (here, is a d‐plane in the n‐space ℝn of x = (x′, x″)), with n = 6N, d = 3 (N − k), x′ ≡ (r′1, ⃛, r′N), x′ ≡ (r1″, ⃛, r″N ()). In this way, the problem is reduced to investigation of the properties of the functions . For a normalizable N – DM, it is proved that are bounded functions. The properties of implied by the N‐DM permutational symmetry, Hermiticity, and positive definiteness are found. A formal procedure of reconstruction of all N‐DM corresponding to a given k‐RDM is proposed. © 1995 John Wiley & Sons, Inc.
Solvent effects in density functional calculations of uracil and cytosine tautomerism
Authors: Paglieri Luca , Corongiu Giorgina , Estrin Darío A. 
Published: December 2004

AbstractThe effects of the solvent on the tautomeric equilibria of cytosine and uracil are studied using Onsager's reaction field model in the framework of density functional theory. In this model, the solute molecule is placed in a spherical cavity of radius ao immersed in a continuous medium with a dielectric constant e, treating the solute‐solvent electrostatic interactions at the dipole level. The cavity radius is evaluated by determining the molecular volume with a quantum mechanical approach. The solvent effect brings significant changes in the geometrical parameters of some cytosine tautomers, but only very small changes to those of the uracil tautomers. Our results are in good agreement with available experimental results and confirm that the polarization of the solute by the continuum has important effects on the absolute and relative solvation energies. Frequency shifts and intensity variations in the infrared spectra due to the presence of the solvent are also presented. © 1995 John Wiley & Sons, Inc.
Chemical reactivity trends of ergotamine and butenolide from electrostatic potentials and charge sensitivities
Authors: Mrozek Janusz , Michalak Artur 
Published: December 2004

AbstractA set of reactivity indices, including maps of the electrostatic potential and local and condensed Fukui function (FF) indices in the atomic resolution, are reported for two vasoconstricting mycotoxins: butenolide and ergotamine; both the finite difference approach of Parr and Yang as well as charge sensitivity analysis, determining the charge responses via the inversion of the hardness tensor, have been used to generate the FF data. These two routes of arriving at the atomic FF indices provide an opportunity to evaluate the available parametrizations of the semiempirical NDDO‐type of methods which have been used to determine the input charge distribution; namely, the best parametrization should generate consistent FF predictions resulting from both approaches. For butenolide, the MNDO parametrization was found to fulfill this consistency requirement. The chemical reactivity information has been used to trace possible similarities in reactivity trends of the butenolide molecule and the related fragment of ergotamine, toward hypothetical nucleophilic, electrophilic, and radical attacks. These predictions have been compared to experimental data available for other unsaturated lactones. © 1995 John Wiley & Sons, Inc.
A combined study by XPS, Raman, diffuse reflectance spectroscopy and analytical electron microscopy of the influence of the sequence of impregnation on the state and dispersion of cobalt in CoMo/Al2O3 catalysts
Authors: Apecetche M. A. , Houalla M. , Delmon B. 
Published: December 2004

AbstractXPS, Raman, diffuse reflectance spectroscopy and analytical electron microscopy techniques were used to investigate the influence of the sequence of impregnation (Mo or Co first) on the state and dispersion of cobalt in CoMo/Al2O3 catalyst in its precursory oxidic state (3 wt% Co3O4 and 12 wt% MoO3). The results indicate that impregnating Mo first promotes both the dispersion of the cobalt containing phase and the formation of CoAl2O4 like species at the expense of ‘free’ cobalt in Co3O4 like compounds.
Progress of the ASTM E‐42 committee on surface analysis
Authors: Powell C. J. 
Published: December 2004

AbstractThe American Society for Testing and Materials (ASTM) formed Committee E‐42 on Surface Analysis in 1976. Subcommittees have been established for the four surface‐analysis techniques in common use (AES, XPS, ISS, and SIMS) and for terminology, ion‐beam sputtering, standard reference materials, and editorial processing. The principal objective of the committee and its component groups is to advance the field of surface analysis and the quality of surface analyses through the development of appropriate standards, standard procedures, standard materials, roundrobins, symposia, workshops, and publications. A review is given of recent activities of the committee and of work in progress. The success of the committee will depend a great deal on adequate communication and coordination with other interested individuals and groups to ensure the adequacy and quality of proposed standards and to prevent unnecessary confusion or duplication of effort. Suggestions are made for this purpose.
Growth of a contamination layer
Authors: Ebel Maria F. 
Published: December 2004

AbstractThe energy dependence of the mean free path of electrons in a solid material can be used for a simple determination of the reduced thickness of a contamination layer without application of the variation of the electron take‐off angle. Moreover, it allows the observation of the growth of a contamination layer as well as the determination of the reduced thickness of the contaminations on other specimens in the sample chamber under the same experimental conditions.
Ellipsometric approach for evaluation of optical parameters in thin multilayer structures
Authors: Paneva A. , Szekeres A. 
Published: December 2004

AbstractAn ellipsometric approach has been proposed for the determination of the optical parameters of a transition layer existing between a substrate and a grown film. In the approach the functions tan ψ cos Δ and tan ψ sin Δ vs. top layer thickness are approximated by the appropriate polynomials. The absolute terms of the polynomials are connected with the ellipsometric angle ψ′ and Δ′ related to the substrate‐transition layer system. For finding the tan ψ cos Δ and tan ψ′ sin Δ′ vs. top layer thikness dependences it is necessary either to each gradually the top layer and to make ellipsometric measurements after each etching step or to trace ellipsometrically the growth process of the film in situ. Since the approximation does not require the complete removal of the top layer, the proposed approach is very useful for obtaining the optical parameters of a thin intermediate film in a double‐layer—substrate structure when complete removal of the top layer is impossible without damaging the layer underneath. The error introduced by the approximation is ∼0.016°, which is within the range of the standard ellipsometric accuracy for ψ and Δ.
Stabilizer insights by NMR spectroscopy
Authors: Fisch Michael H. 
Published: December 2004

AbstractDuring the past decade, advances in both hardware and software have made NMR spectroscopy an enormously powerful analytical technique. In this paper, the author presents examples of the use of NMR in support of vinyl stabilizer research; he also covers representative practical applications of proton, carbon, phosphorus, and tin NMR.
Color considerations in a world free of heavy metals
Authors: Reger Eric J. 
Published: December 2004

AbstractEnvironmental concerns have once again become the focus of social and political discussions. This concern has spawned a number of far‐reaching legislation. “SARA Title III” and “Prop 65” have become everyday terms and represent two attempts at addressing hazardous materials in our environment. This paper examines the impact of such legislation on colorants for plastics and discusses the options available. This impact is not only felt by the color concentrate producer; but also, on plastics processors and ultimately the consumer.
PVC markets survive regulations, greenpeace, and perestroika
Authors: Goodman Donald 
Published: December 2004

AbstractThe markets for PVC resins have survived the continuing challenges provided by government regulations, competitive adversaries, and the changing geopolitical arena. Recent regulations regarding what constitutes a hazardous waste, the presence of heavy metals in the PVC product or compound, and how PVC products are thrown away have threatened market share. Resilient and robust PVC is meeting these challenges while growing nationally and globally. This review examines how PVC markets have been able to thrive in the face of Greenpeace attacks against chlorine‐containing products. Projections are made about the global future of PVC markets with the advent of Europe 1992 and the opening of Eastern Europe and Russia.
Über ein neues Verfahren zur Herstellung von Metallboriden der Übergangsmetalle, insbesondere von Titan‐und Zirkonborid
Authors: Kieffer R. , Benesovsky F. , Honak E. R. 
Published: December 2004

AbstractDurch Umsetzung von metallischem Titan bzw. Zirkon mit Borcarbid unter Zusatz von Borsäureanhydrid bzw. TiO2 oder ZrO2, gelingt es, kohlenstoffarmes TiB2 und ZrB2 herzustellen. Das Borcarbidverfahren ist zur technischen Erzeugung von Metallboriden geeignet. — Es wurden einige physikalische Eigenschaften an Heißpreßkörpern aus TiB2 und ZrB2 bestimmt und mit den Werten anderer Diboride der Übergangsmetalle der 4., 5. und 6. Gruppe des Periodensystems verglichen.
Bindekräfte im Bortrifluorid und Tetrafluoroborat‐lon
Authors: Goubeau J. , Bues W. 
Published: December 2004

AbstractAus den Spektren von (10BF4)− wird die Bindekraft BF berechnet. Der erhaltene Wert wird mit der aus den bekannten Spektren von 10BF3 und 11BF3 berechneten Bindekraft verglichen. Der Zustand der BF‐Bindung im BF3 und BF4− wird diskutiert.
Über Acidiumsalze Ramanspektroskopische und viscosimetrische Untersuchungen über die Strukturen der wasserfreien Salpeter‐, Phosphor‐ und Überchlorsäure sowie des Phosphorsäureperchlorats
Authors: Simon A. , Weist M. 
Published: December 2004

AbstractEs werden die RAMAN‐Spektren der wasserfreien Säuren HNO3, HClO4 und H3PO4 sowie die Spektren von Mischungen von wasserfreier Überchlorsäure und wasserfreier Phosphorsäure in verschiedenen Molverhältnissen mitgeteilt. Während die wasserfreie Salpetersäure ein Acidiumsalz bildet und die NO3‐Hauptfrequenz auch im wasserfreien Zustand aufweist, bildet die wasserfreie Überchlorsäure weder Acidium‐ noch Hydroniumsalze. Die wasserfreie Orthophosphorsäure unterliegt beim Schmelzen einem freiwilligen Anhydrisierungsprozeß, bei dem 3 Moleküle Orthophosphorsäure übergehen in Pyrophosphorsäure und primäres Hydroniumphosphat, wobei nur das H2PO Ion das spektrale Bild bestimmt. Die H2PO‐Ionen sind über Wasserstoffbrücken miteinander verknüpft, so daß das Ion tetraedrische Struktur nach dem spektralen Befund hat. Bei Zusammengeben von wasserfreier Überchlorsäure und wasserfreier Phosphorsäure in verschiedensten Molverhältnissen resultieren beim Abkühlen feste Körper, die nach der Analyse stets die Zusammensetzung von einem Mol Überchlorsäure und einem Mol Phosphorsäure haben. In der Schmelze zeigen diese Körper neben der Pseudoform der Überchlorsäure auch die Linien des ClO4‐Ions und das Spektrum der wasserfreien Phosphorsäure. Das Kation P(OH)+4 hat wahrscheinlich auch tetraedrische Struktur.Mit diesen spektroskopischen Daten decken sich die Viscositätsmessungen, die bei den Mischungen der wasserfreien Säuren nur ein Maximum der Viscosität bei 50:50 Molprozenten aufweisen. Der Verlauf der Viscositätskurven zeigt, daß die Phosphorsäure durch Wasserstoffbrücken eine weitgehende Verknüpfung ihrer Moleküle aufweist, während das bei Salpetersäure und Überchlorsäure kaum der Fall zu sein scheint. Im System Überchlorsäure/Wasser ist aus den Viscositätskurven ein Hydroniumperchlorat und auch ein Dihydrat erkennbar.
Über Fluorokomplexe des Palladiums und des Goldes
Authors: Hoppe Rudolf , Klemm Wilhelm 
Published: December 2004

AbstractDie Darstellung von Verbindungen des Typs M2[PdF6] und M[AuF4] (M = Alk.‐met.) wird beschrieben. Cs2[PdF6] und Rb2[PdF6] kristallisieren im K2[PtCl6]‐Gitter, K2[PdF6] kristallisiert hexagonal. Alle Verbindungen sind hell zitronengelb bis gelb gefärbt und gegen Feuchtigkeit sehr empfindlich; unter Abgabe von HF findet Hydrolyse statt. Bei der Darstellung der Verbindungen M[AuF4] werden Reaktionszwischenprodukte abgefaßt, die rot aussehen und gegen Wasser beständiger als die Verbindungen M[AuF4] sind. Es handelt sich um Chloro‐Fluoro‐Aurate(III).
Schwefel‐Thermitverfahren zur Darstellung von Rein‐Silicium
Authors: Wartenberg H. V. 
Published: December 2004

AbstractEs wird der Mechanismus des alten KÜHNEschen Verfahrens klargestellt, aus Al, SiO2 und S nach einem Thermitprozeß eine an Si hochprozentige SiAl‐Legierung herzustellen (§ 1–4). Das Verfahren wurde apparativ und durch Verwendung reinster erhältlicher Materialien so weit ausgebildet, daß ein 64proz. Silumin resultierte, aus dem nach einem früheren Verfahren durch Chlorierung ein Si mit unter 10−20% Fe + Al hergestellt werden konnte (§ 5). Die Gründe werden erläutert, warum die Reinigung nicht weitergetrieben werden kann (§ 6). Der spez. Widerstand des gewonnenen Si war rund 15 Ω cm (§ 7).
Zur Struktur der Metawolframate
Authors: Schott G. , Harzdorf C. 
Published: December 2004

AbstractFür die Deutung der Struktur des Metawolframations stehen folgende Formulierungen zur Diskussion: magnified image die sich bezüglich ihrer Basizität bzw. ihres Konstitutionswassergehaltes unterscheiden. Untersuchungen an den Substanzen Li6[H2(W3O10)4] · aq, Na6[H2(W3O10)4] · aq und K6[H2(W3O10)4] · aq fällen die Entscheidung zugunsten des Strukturvorschlages II.
Zur Darstellung von Lösungen freien Hydroxylamins durch Ionen‐Austausch
Authors: Holzapfel Heinz 
Published: December 2004

AbstractEs wird gezeigt, wie man wäßrige Lösungen von freiem Hydroxylamin einfach und bequem durch Anionen‐Austausch an Wofatit L 150 in OH‐Form aus Hydroxyl‐ammonium‐Salzen gewinnen kann, wobei unmittelbar eine Konzentration von 5,2–5,7 Mol/l zu erreichen ist, die durch eine Modifizierung der Methode erhöht werden kann. Einfacher ist es noch, die nach unmodifizierter Methode dargestellten 5,2–5,7 m‐Lösungen durch Ausfrieren in sehr schonender Weise zu konzentrieren. Die gewonnenen Lösungen sind recht stabil, so hält sich eine 1 m‐Lösung bei Zimmertemperatur zehn Tage lang fast unverändert. Kupfer‐Ion katalysiert auch in minimaler Konzentration die Selbstzersetzung äußerst stark.Weiterhin wird eine sehr einfache Apparatur angegeben, die Austauscher‐Harz, z. B. Über Nacht, automatisch regeneriert und anschließend weitgehend auswäscht, so daß es am nächsten Morgen wieder einsatzbereit ist.
Darstellung und thermogravimetrische Untersuchung einer neuen Tellur—Brenzcatechin‐Verbindung
Authors: Antikainen P. J. , Mälkönen P. J. 
Published: December 2004

AbstractEs wird gezeigt, daß Tellursäure mit Brenzcatechin in wäßriger Lösung eine sehr schwer lösliche, kristallisierbare Te(IV)‐Verbindung bildet, die nach thermogravimetrischen Untersuchungen die Struktur Te
equation image
besitzt. Die thermischen Zersetzungsreaktionen dieser Verbindung werden diskutiert. Das IR‐Spektrum des Chelates wird mit den Spektren des Brenzcatechins und der Tellursäure verglichen. Ferner werden die thermogravimetrischen Kurven von Tellursäure und Brenzcatechin dargestellt. Es konnte weiterhin thermogravimetrisch beobachtet werden, daß Tellursäure und Brenzcatechin auch in der Schmelze miteinander reagieren und geringe Mengen der erwähnten Te(IV)‐Verbindung bilden.
Maßanalytische und gewichtsanalytische Untersuchungen an Kobaltpulver
Authors: Skaupy Franz , Herrmann Artur 
Published: December 2004

AbstractEine früher beschriebene(1) maßanalytische Methode wurde auf Kobaltpulver angewendet, das einige Schwierigkeiten bietet. Durch gewichtsanalytische Bestimmungen einerseits durch Reduktion, andererseits durch Oxydation der Pulver wurde ein Vergleich geschaffen.
On the nature of LUNDEL and KNOWLES rhenide ion
Authors: Ginsberg A. P. , Koubek E. 
Published: December 2004

AbstractEvidence is presented showing that the assumption that LUYUELL and KNOWLES rhenide is identical with the product obtained by reducing aqueous perrhenate with an alkali metal, recently shown to be a hydride, is incorrect. Absorption spectra of acid rhenide solutions show that. a complex of Re‐ cannot be present, and so it is concluded that rhenide is a hydride complex of rhenium different, from that obtained by reduction with alkali metals.
Über die Darstellung eines neuen Siliciumsubnitrides (Si6N2)n
Authors: Hengge E. 
Published: December 2004

AbstractCalciumdisilicid reagiert mit Ammonhalogeniden im feingepulverten Zustand beim Erhitzen unter Bildung eines Siliciumsubnitrides (Si6N2)n und dem entsprechenden Calciumhalogenid.
Über die Polymorphie von Natriummetavanadat
Authors: Lukács Ileana , Strusievici Constanta 
Published: December 2004

AbstractMit Hilfe von Röntgenaufnahmen (nach GUINIER), von IR‐Spektren und der Differentialthermoanalyse wurde fur das Xatriummetavanadat bei 403–405°C eine irreversible Umwandlung festgestellt.
Über Alkalichromate(V)
Authors: Scholder R. , Schwarz H. 
Published: December 2004

AbstractDarstellung und chemische Eigenschaften von Alkalichromaten(V) des Formeltyps Me3CrO4 (Me = Li, Na) werden beschrieben und die Ergebnisse der röntgenographischen und magnetochemischen Untersuchungen mitgeteilt. Versuche zur Darstellung von Alkalimetachromaten(IV), Me2CrO3, blieben ohne Erfolg; man erhält an Stelle der Chromate(IV) stets äquimolekulare Gemische von Me3CrO4 und MeCrO2.
New types of cation‐order in the rocksalt lattice: The structure of Li3SbO4 and Li3NbO4
Authors: Blasse G. 
Published: December 2004

AbstractLi3SbO4 and Li3NbO4 have structures based on a 3 : 1 order of univalent and pentavalent cations in the rock salt lattice, the order being different for the two compounds.
Stabilities of Bivalent Metal Chelates of 3‐hydroxy‐3‐phenyl‐l‐o‐chlorophenyltriazene
Authors: Purohit D. N. , Sogani N. C. 
Published: December 2004

AbstractStabilities of palladium, copper, nickel, zinc, and manganese chelates of 3‐hydroxy‐3‐phenyl‐1‐o‐chlorophenyltriazene have been determined in 70% v/v dioxan‐water mixture by employing BJERRUM‐CALVIN pH titration technique. The titration medium was maintained at a constant ionic strength (0.1 M, KCl) and at a temperature, 25±0.5°.log K, palladium 20.428, copper 19.856, nickel 14.115, zinc 13.167, and manganese 9.773.