bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of the Influence of Concentration on the Photoluminescence Decay Time of Solutions
Authors: Twardowski R. , Bojarski C. 
Published: February 2015

Abstract
A formula for the donor photoluminescence decay time in its dependence on the concentrations of donor D and acceptor A has been derived from equations for the non-radiative excitation energy transfer between randomly distributed donor and acceptor molecules within a nonactive medium. In the limit [D]/[A] → 0 the formula becomes identical with that of Galanin [7], while in the absence of concentration quenching the fluorescence decay time does not depend on the concentrations.
Solvent Effects on the Spectral Properties of the Methine Dyes
Authors: Salamon Z. , Skibiński A. 
Published: February 2015

Abstract
The spectral characteristics (absorption, fluorescence and lifetimes of fluorescence) of methine dyes in different solvents are presented. The results show that the methine dyes in polar solvents emit a dual fluorescence. From the dependence of the fluorescence spectrum on the dye con-centration it is suggested that excimer formation is responsible for the second band of fluorescence.
Conformation and Structure of Ethylbenzene in the Vapour Phase
Authors: Scharfenberg Peter , Rozsondai Béla , Hargittai István 
Published: February 2015

Abstract
The molecular structure of ethylbenzene has been studied by gas electron diffraction. Experi-mental intensities and radial distribution are well reproduced by an average structure with r = 70(3)°, where r is the angle between the C—C—C(H3) plane and the ring plane, mean (rg) bond lengths (C-C)phenyi = 139.9(3) pm, Cphenyi-C(H2) = 152.4(9) pm, C(H2)-C(H3) = 153.5(12) pm, C—H = 109.4(4) pm, and bond angle C-C-C(HS) = 111.8(15)°. (Estimated total errors are parenthesized.) An also acceptable perpendicular model (r = 90°) is accompanied by very large vibrational amplitudes, while the coplanar conformation (r = 0°) is excluded. Mixtures of conformers fit the experimental data as well. The barrier to rotation of the phenyl group is estimated from the average structure to be about 7 kJ mol -1 . According to CNDO/2 calculations, only the perpendicular form is stable. The results of a geometry optimization are shown.
Vibrational Total Energy Distributions in Terms of Symmetry Coordinates, Forces and Momenta
Authors: Alix Alain J. P. , Rytter Erling 
Published: February 2015

Abstract
The fundamental definitions of the Total Energy and of the Vibrational Total Energy Distributions are presented in details in terms of either symmetry coordinates, or generalised symmetry forces, or generalized symmetry coordinates. This, give now a uniform tool for physicists and chemists in the field of characterisation of the normal vibrational modes of polyatomic molecules.
A Contribution to the Investigation of T2-Relaxation with a Pulse Spectrometer
Authors: Beslmann G. , Dreizler H. 
Published: February 2015

Abstract
We investigated the pressure dependence of the T2- relaxation time for several rotational transitions of acetal-dehyde, CH3CHO. No difference in the relaxation of A- and E-species transitions could be detected. The analysis was performed in the time and frequency domain.
Eine kanonische Transformation als Lösungsvorschlag für eine Funktionalgleichung
Authors: Wahl F. 
Published: February 2015

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
Experimental Evidence for two Kinds of Defects in Amorphous Fe80B20
Authors: Nold E. , Steeb S. , Lamparter P. 
Published: February 2015

The scattering of cold neutrons (λ = 1 nm) with amorphous Fe80
11B20 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
Dipole Moment and Dielectric Relaxation of Some Aromatic Ethylenes and Butadienes
Authors: Hanna F. F. , Abdel-Nour K. N. , Risk J. E. 
Published: February 2015

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 -OCH3 group in the 1,1-bis-p-methoxy-phenylethylene is hindered to a large extent. The orientation of the -OC2H5 and -OC3H7 groups in the corresponding molecules are restricted due to steric hindrance
Exciton Phosphorescence of p-Terphenyl Crystal at 300 K
Authors: Morikawa Eizi , Kotani Masahiro 
Published: February 2015

Abstract
Exciton phosphorescence from pure p-terphenyl crystals was observed at 300 K. The 0-0 band of the phosphorescence spectrum was found at 20.4 X 103 cm-1 . The vibrational progression of 1.46 x 103 cm-1 is present. The maximum exciton lifetime observed was 200 ms. The excitation spectrum of the exciton phosphorescence differs considerably from that observed in glassy solution, but is poorly structured as well. The absorption coefficient near the origin is small. The absence of sensitized delayed fluorescence from doped tetracene suggests that the triplet energy transfer to this guest is not diffusion limited.
EPR Study of the Nematic Liquid Crystals: PEBAB and EBRA
Authors: Rao A. S. N. , Murty P. Narayana , Murty C. R. K. , Reddy T. Rs. 
Published: February 2015

Abstract
By EPR two nematic liquid crystals PEBAB and EBBA were investigated. The experimental variation of the order parameter with temperature is corroborated with theory. In EBBA a spectrum reminiscent of glassy nature is observed at - 60° C.
Repulsion Phenomena in Thin Layers of Alcoholic Solutions of Tetrabutylammonium Iodide
Authors: Peschel G. , Belouschek P. 
Published: February 2015

Abstract
The structural disjoining pressure of methyl-, ethyl-, n-propyl, and n-butyl alcohol was deter-mined in thin layers between highly smooth rutile surfaces when tetrabutylammonium iodide was added. The a verage thickness of the oriented solvation layers per interface turned out to be largest for methyl alcohol (about 1.5 nm) and decreases like the disjoining pressure when passing to the related alcohols with longer chain lengths. Tetrabutylammonium iodide clearly reduces the thickness of the boundary layer with increasing concentration.
Limitations on Mass Separation by the Weakly Ionized Plasma Centrifuge
Authors: Wijnakker M. M. B. , Granneman E. H. A. 
Published: February 2015

bstract
A In weakly ionized argon and xenon rotating plasmas the rotational velocity and the temperature and pressure distribution have been measured.
The stationary discharge is generated by two opposed cathode-anode configurations. The arc current of 100 A is drawn across an axial magnetic field up to 0.26 T. The filling pressure ijs varied between 1 and 10 torr.
The rotational velocity is found to be proportional to the discharge current and the magnetic field and inversely proportional to the viscosity of the neutral gas. The rotational kinetic energies of the particles in the argon and xenon discharge are about equal. Because the temperature of the argon discharge is lower than that of the xenon discharge, the pressure rise in radial direction due to centrifugal forces is steeper for the former.
A theoretical analysis taking into account viscous dissipation as the only heating mechanism yields a heavy particle temperature T which imposes an upper limit to the ratio X =½m υθ
2/kT of order unity. The maximum attainable separation factor α is therefore limited in these types of centrifuges. Experimentally, in the parameter region studied, X is found not to exceed a value 0.4 in argon discharges and 0.2 in xenon discharges. A rough estimate shows that besides viscous dissipation other heating mechanisms are also important. Ohmic heating, for instance, is at least a factor 6 larger than the viscous dissipation.
Über einige präparative Probleme zum Hexachlorotechnetat und ihren Einfluß auf die Messung der Zerfallskonstanten des 99mTc in Hexahalogenokomplexen / About some preparative problems concerning hexachlorotechnetate and their influence on the measuring of the decay constant of 99mTc in hexahalogeno complexes.
Authors: Dostal K.-P. , Bayerl B. 
Published: February 2015

Abstract
A discrepancy between theoretical and experimental values concerning the variation of decay constant of 99m Tc is cleared up. A new preparation of hexachlorotechnetate complex by reduction of pertechnetate ion with hydrazine is given. The corrected experimental results are
λ(TcO4-) -λ(TcCl6--) = (1,93 ± 0,12) · 10-3 1λ,
λ(TcO4-) -λ(TcBr6--) = (2,44 ± 0,30) · 10-3 λ,
λ(TcO4-) -λ(TcJ6--) = (3,22 ± 0,29) · 10-3 λ.
Die Viskositätsabhängigkeit der Fluoreszenz - Anisotropie und der Lebensdauer von Trans-Stilben / Influence of Viscosity upon the Anisotropic Fluorescence and Lifetime of trans-Stilbene
Authors: Alicka M. , Bauer R. K. , Kawski A. 
Published: February 2015

Abstract
The fluorescence anisotropy r and lifetime τF of trans-stilbene in different solvents has been measured and the dielectric relaxation time from Perrin and Debye equations has been determined. The fluorescence lifetime in the viscosity region from 0.321 to 61.92 Nm-2s, varies between 30 and 152 ps.
Investigation of Molecular Motion in Smectic Phases of the Liquid Crystal TBBA by NMR Relaxation Dispersion
Authors: Mugele Th. , Graf V. , Wülfel W. 
Published: February 2015

Abstract
The proton spin T1 relaxation dispersion in the smectic A and C phase of TBBA, and for comparison also in the nematic phase, have been studied using time dependent fast field-cycling techniques in the Larmor frequency range from νp = 100 Hz to 44 MHz. Our measurements considerably extend recent ones by Blinc et al., performed with other NMR methods for frequencies ≧ 140 kHz. The new experimental data are consistent with the reported ones for Sm C but not for Sm A, the difference being that the essential T1 dispersion observed with our technique occurs at much lower frequencies, namely below about 100 kHz. As a consequence, the relaxation dispersion for both smectic phases looks very similar. It can be described quantitatively in terms of relaxation by "nematic-like" order fluctuations, self-diffusion, and by a third molecular mechanism with (for simplicity) Debve-like power spectrum, which is possibly a second type of order fluctuation or a molecular rotation about the short axis. The analysis reveals surprisingly far going parallels between the spin relaxation of simple smectics and that of high-temperature nematics like PAA.
The Influence of the Grain Shape on X-Ray Line Broadening
Authors: Schattschneider P. , Wagendristel A. 
Published: February 2015

Abstract
The analysis of X-ray reflections allows for the determination of the grain dimension in the direction of the bisector of the incident and scattered radiation. It is shown that correct results will be obtained only as long as the grain dimensions perpendicular to this direction are sufficiently large. The possible errors are estimated. The conditions for the determination of the shape anisotropy are discussed.
Semiempirical Studies of Inner-Core Energy Levels. IV. ESCA Shifts of Nitrogen Atoms in Different Chemical Environments by the SCC-MO Method
Authors: Maksić Z. B. , Rupnik K. 
Published: February 2015

Abstract
The binding energy shifts of the Is levels of nitrogen atoms in 15 different bonding situations are calculated by the self-consistent charge molecular orbital (SCC-MO) method employing an electrostatic potential model in the point charge approximation. The standard deviation of the obtained correlation is ~ 0.5 eV, which is substantially better than the earlier CNDO/2 GPM and RPM results. The scatter of the correlated values is diminished to roughly 1/3 of the previous CNDO/2 results. The merits and shortcommings of the electrostatic potential model are briefly discussed. It is concluded that the present approach provides a useful tool for studying ESCA shifts in large molecules of biochemical interest.
Effect of Acceptor Concentration upon Donor Fluorescence Decay and Quantum Yield
Authors: Bojarski C. , Grabowska E. 
Published: February 2015

Abstract
The fluorescence decay times (τ/τ0) and quantum yields (η/η0) of rhodamine 6G (donor) in their dependence on the concentration of malachite green (acceptor) in ethanol were measured for the donor to acceptor concentration ratios γᴅ/γᴀ 3.48 and 0.35. At fixed γᴀ, the values of τ/τ0 and η/η0 are markedly lower for the systems with higher γᴅ/γᴀ. The experimental results are compared with the theory of a multistep excitation energy transfer from donor to acceptor. Good agreement between theory and experiment was found for the critical distances ROD = 60.7 Å and ROA = 53.8 Å calculated from spectroscopic data. In the case of γᴅ/γᴀ = 0.35, the experimental results can also be properly described using the Förster-Galanin theory, whereas for the system with γᴅ/γᴀ - 3.48 the multistep energy transfer plays a significant role.
Functional Quantum Theory of the Nonlinear Spinor Field as a Lepton-Hadron Model with Quark-Confinement
Authors: Stumpf H. 
Published: February 2015

Abstract
The non-canonical Heisenberg dipole regularization of a nonlinear spinor field is interpreted as a system of lepton quark pairs in the one-particle sector. In the frame-work of functional quantum theory a method is given to derive an independent lepton-quark dynamics with quark confinement from the fundamental spinor field.
Kraftkonstanten des VO4
3- -Ions im Zirkon-Gitter [1] / Force Constants of the VO4
3- Ion in the Zircon Lattice
Authors: Escobar Marta E. , Baran Enrique J. 
Published: February 2015

Abstract
Force Constants of the VO4
3- Ion in the different rare earth orthovanadates of the zircon type have been computed using a modified valence force field and recently reported Raman data. It is shown that the V-O bond strenghtening runs parallel to the unit cell contraction. The Raman spectrum of the tetragonal modification of LaVO4 is reported for the first time.
Diffusion in Binary Nonelectrolyte Solutions
Authors: Haase R. , Jansen H.-J. 
Published: February 2015

Abstract
For binary liquid mixtures of nonelectrolytes, we consider the dependence of the diffusion coefficient on composition and temperature, making use of an analytical expression for the kinematic diffusion coefficient (diffusion coefficient divided by thermodynamic factor). We present recent experimental data for the ideal liquid system chlorobenzene + bromobenzene and for the non-ideal liquid system water -f methanol as well as literature data for other non-ideal mixtures.
Determination of a High Potential Barrier Hindering Internal Rotation from the Analysis of the Ground State Spectrum: The Case of Ethyl Cyanide
Authors: Boucher D. , Dubrulle A. , Demaison J. , Dreizler H. 
Published: February 2015

Abstract
The ground state rotational spectrum of ethyl cyanide has been reinvestigated between 8 and 250 GHz. The barrier potential V3 is calculated from 11 high J, ground state transitions which were found split into doublets. V3 is 3007 cal/mole, assuming Iα = 3.167 u Å2 and ∢ (i,a) = 48.65°. The splittings of the K-doublet transitious have also been analyzed.
Non-Equilibrium Relaxing Gas Flow Behind Three Dimensional Unsteady Curved Shock Wave
Authors: Sharma V. D. , Shyam Radhe 
Published: February 2015

Abstract
A shock wave is assumed to exist in a three-dimensional unsteady flow of a relaxing gas. The variation of flow parameters at any point behind the shock surface is determined in terms of the shock geometry and the upstream flow conditions. The expressions for the vorticity and the curvature of a streak line at the rear of the shock surface are also determined in terms of the known quantities.
Internal Cation Mobilities in the Molten Systems (Li-Na)NO3 and (Na-Cs)NO3
Authors: Yang Chao-cheng' , Takagi Ryuzo , Okada Isao 
Published: February 2015

Abstract
For the molten salt systems (Li-Na)NO3 and (Na-Cs)NO3, relative differences of internal mobilities have been measured with the Klemm method. The internal mobilities, b, are calculated from these data and the available conductivity data. In the mixtures of the former system, bNa is always greater than bLi. In the latter system, the Chemla crossing point occurs. It is found that bLi and bNa in the binary alkali nitrate systems so far investigated are well expressed, except at small molar volumes, by b = {A/(V - V0)} exp(- E/RT) with constant A and E, where V is the molar volume and F° a constant for bu and nearly a constant for The values of bCs at equal concentrations of CsNO3 in the systems (Li-Cs)NO3 and (Na-Cs)NO3 are practically equal. The internal mobilities obtained are discussed in terms of free space, mutual ionic attraction and thermal agitation.
Einfluß von Substituenten auf die Fluoreszenzquantenausbeute bei Donator-Akzeptor-substituierten trans-Stilbenen
Authors: Gloyna D. , Kawski A. , Gryczyński I. 
Published: February 2015

Abstract
For 4'-acceptor substituted 4-dimethylaminostilbenes 1 the fluorescence quantum yield φf increases in n-heptane and toluene with decreasing acceptor interaction (i.e. with decreasing polarity in the S1-state). At the same time, the lifetimes τf
w change with φf so that kf
n remains approximately constant. Changes in φf for compounds 1 result from a strong change of the rate constant ktp of radiationless deactivation. This is interpreted in terms of the decreased stabilization of the Si-state occurring with the increase in the polarity of the investigated compounds in non-polar solvents, and remains in good agreement with the calculations carried out previously.
Reaction of the Ground and Metastable Excited C+ and N+ Ions with C2H4, CH3Cl and SO2 Gases at 300 K
Authors: Rakshit Asit B. 
Published: February 2015

Abstract
Rate coefficients and product distributions were measured for the reactions of C+ and X+ ions with C2H4, CH3Cl and SO2. The reactant ions were produced by electron impact using electron energies of 30 V and 100 V and then injected into a flow tube. The product ion distributions for these reactions depend significantly on the electron energy at which the reactant ions are formed. Reactions with CH3Cl and SO2 of ions formed at 100 V yield product ion distributions with a preference for fragmentation channels. In the case of C2H4, the simple charge transfer channel is favoured at high energy. Various new product ions have been identified from these studies, some of which having not been observed previously 7 . Rate coefficients for these reactions at 30 V agree closely with the calculated values using Langevin and ADO theory.
Collision Broadening and Shift of the 535.0 nm Tl Line Accompanying the Photodissociation of Thallium Iodide Perturbed by Noble Gases
Authors: Lisicki E. , Bielski A. , Szudy J. 
Published: February 2015

Abstract
The shape and shift of the 535.0 nm thallium line resulting from the photodissociation of thallium iodide perturbed by krypton and xenon were investigated at low densities. The Doppler and collision broadening components of the line shape have been determined. The linear dependence of both the Lorentzian half-width and the shift on the perturbing gas density was found and interpreted in terms of Van der Waals and Lennard-Jones potentials.
Rotational Motions of Synthetized Yt-Base, Free or Bounded to Adenine, in Solvents of Various Viscosities
Authors: Gryczyński I. , Kawski A. , Paszyc S. , Skalski B. 
Published: February 2015

Abstract
Mean lifetimes in the singlet excited state and emission anisotropics of Yt base and Yt (CH2) 5-adenine were measured as a function of solvent viscosity. Effective volumes of the molecules studied and the cor-responding radii were determined. The fluorescence depolarization of Yt-base in solutions was found to be due to the rotational motion, for the most part about the main x-axis.
Magnetic Field Dependence of Molecular Quantum Beat: Biacetyl
Authors: Henke W. , Selzle H. L. , Hays T. R. , Schlag E. W. 
Published: February 2015

Abstract
The effect of an external magnetic field on the decay of an excited single rotational state of the 1Au electronic state of biacetyl is observed in a hypersonic jet experiment after narrow bandwidth laser excitation. The lifetime of the ex-cited state decreases already at low magnetic fields and the molecular quantum beat vanishes.
Host Spin-Lattice Relaxation Narrowing in Pr2Co3(NO3)12 · 24 H2O: Mn2+ \ Gd3+ Single Crystals
Authors: Jain Vimal Kumar 
Published: February 2015

Abstract
Electron paramagnetic resonance of Mn2+ and Gd3+ in single crystals of Pr2Co3(NO3)12 · 24 H2O has been studied at X-band at 305 and 77 K. Mn2+ substitutes at two types of Co2+ sites whereas Gd3 substitutes at the single type of Pr3+ site in the lattice. The spin-Hamiltonian parameters have been evaluated. Observation of resolved Mn2+ and Gd3+ spectra at 305 K and their broadening on lowering the temperature are discussed in terms of host spin-lattice relaxation narrowing.
The Spectrum of Lanthanum Oxide: A Reanalysis of the Rotational Data
Authors: Bernard A. , Sibaï A. M. 
Published: February 2015

Abstract
A consistent set of improved rotational constants is derived for the X2Σ+, A′2⊿r, A2Πr, B2Σ+,and C2Πr electronic states of lanthanum oxide from the reanalysis of all available data. These constants are obtained from a global fit of the respective bands by a "Direct Approach" technique using complete Hamiltonian matrices for the description of Π and ⊿ states. In order to fit the lines accurately it is shown necessary to include centrifugal distortion effects in the spin-orbit interactions (AJ, AJ and AJJ respectively in A′, and A and C states) as well as in Λ-doubling (PJ pJJ,qJ in C state) and spin-rotation interactions (γJ in B state).
More reliable values for the internal partition function and dissociation equilibrium constant of La O are computed for temperatures between 1000 and 8000 K, by taking account of all the known electronic states and using present or recent values for the molecular parameters and dissociation energy.
Some Luminescence Properties of the Laser Dye Stilbene 3
Authors: Bauer R. K. , Balter A. , Kowalczyk A. 
Published: February 2015

Abstract
Absorption and emission spectra of stilbene 3 (Na-bis-ortho-stilbene-sulphonate) were measured and discussed on the basis of quantum-chemical calculations. The decay of the polarized fluorescence was investigated, yielding information about the rotational behaviour of stilbene 3 in solutions.
Raman-spektroskopische Untersuchungen an PCl5
Authors: Brockner Wolfgang , Demircan Bülent 
Published: February 2015

Abstract
Raman spectra of some solid and molten AuCl3-PCl5 mixtures have been recorded. In the system investigated only the compound AuCl3 · PCl5 is found. This adduct is built up by ionic PCl4
+ and AuCl4- units and it should be formulated as PCl4AuCl4. These complex ions are present in the melt too. The thermal stability of AuCl4- is noteworthy, and it is explained by pressure influenced equilibria. Only PCl4AuCl4, besides excess PCl5 or AUCl3, is present in the mixtures.