bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equation of State and Electrical Conductivity of Dense Fluid Hydrogen and Helium
Authors: Redmer Ronald , Juranek H. , Kuhlbrodt S. , Schwarz V. 
Published: December 2003

Abstract
The equation of state of fluid hydrogen, helium, and their mixtures is determined within fluid variational theory. Reactions between the constituents such as dissociation and ionization are considered. Results are given for densities and temperatures relevant for the interior of giant planets. Furthermore, the electrical conductivity is determined within linear response theory. Comparison is performed with available experiments and other theoretical work.
The Transition to the Metallic State in Alkali and Low-Z Fluids
Authors: Nellis W. J. , Chau R. , Edwards Peter P. , Winter Roland 
Published: December 2003

Abstract
We review here experiments that investigate how the electronic properties of five chemically dissimilar fluid elements, hydrogen, nitrogen, oxygen, rubidium and caesium, vary with density beyond their critical points. Remarkably, all five elements in their metallic regime have essentially the same electrical conductivities, close to the predicted minimum metallic conductivity of a high-temperature, disordered metallic fluid. The large differences in their respective metal-nonmetal transition densities are rationalized in terms of each chemical element’s unique atomic properties of size (radial extent of electronic wave function, N.F.Mott) and electronic polarizability (K.F.Herzfeld and D.A.Goldhammer). These experiments thereby highlight the pivotal role of atomic properties in dictating the metallic or nonmetallic status of chemical elements of the periodic classification.
Slow Dynamics Due to the Metal-Nonmetal Transition in Liquids
Authors: Yao Makoto , Kohno Hirotaka , Kajikawa Hiroaki 
Published: December 2003

Abstract
It is well known that the liquid dynamics slows down on approaching the liquid-gas critical point or the liquid-glass transition. Recently we have found by the sound attenuation measurements that the metal-nonmetal (M-NM) transition also induces slow dynamics. In the M-NM transition range of expanded liquid Hg, we have observed anomalous increase in the sound attenuation due to the structural relaxation process. Assuming a simple Debye-type relaxation, we have estimated that the relaxation time should be of the order of nanoseconds and revealed that the relaxation strength has a broad maximum in the M-NM transition range. Moreover, two types of anomalies have been observed also in the semiconductor-metal (S-M) transition range of liquid Te-Se mixtures. We present the recent experimental results of the sound attenuation measurements and discuss briefly the mechanisms of the slow dynamics in the metal-nonmetal transition range of liquids.
Volumetric Properties, Compressibilities and Volume Fluctuations in Phospholipid-Cholesterol Bilayers
Authors: Seemann H. , Winter Roland 
Published: December 2003

Abstract
We conducted detailed measurements of the apparent specific volume of dipalmitoylphosphatidylcholine (DPPC)–cholesterol mixtures in excess water as a function of pressure up to 70MPa (700bar) at 20, 38 and 50°C. The volumetric properties and the isothermal compressibility κ
T of the lipid vesicles were determined at cholesterol concentrations, χchol, ranging up to 50 mol. The thermodynamic data are compared with other physico-chemical properties of phospholipid–cholesterol mixtures. Furthermore, the thermodynamic properties of the system are discussed in the light of the various T, χchol–phase diagrams and computer simulation studies published in the literature.
The Network-Chain Transformation in the Liquid As-Te Mixtures near the Semiconductor-Metal Transition
Authors: Hoshino H. , Endo H. , Maruyama K. 
Published: December 2003

Abstract
The results of neutron diffraction and EXAFS measurements for l-Te and l-As-Te mixtures (10, 20, 30 and 40at. As) are discussed. The g(r) patterns of l-Te show a substantial overlap between the first and second peaks. The first minimum after the first peak of g(r) around 3.2Å is filled up at high temperature. Upon the addition of As to l-Te the first peak of g(r) becomes sharp, implying that As atoms bridge between Te chains and suppress the thermal fluctuations of the inter-chain distances. The filling of the first minimum around 3.2Å observed for l-As-Te mixtures at high temperature is associated with the inter-chain correlation in a densely packed configuration. From the EXAFS analysis of l-As-Te mixtures we conclude that the network structure composed of threefold coordinated As atoms and twofold coordinated Te atoms is transformed into a twofold coordinated chain structure. The network-chain transformation is accompanied by a gradual semiconductor to metal transition. The first sharp diffraction peak observed for l-As20Te80 and l-As40Te60 is related to the Te-Te intermediate range order in -Te-As-Te- or -Te-As-As-Te- chain molecules.
Local Structure of Liquid Te Studied by Neutron Diffraction and EXAFS
Authors: Endo Hirohisa , Maruyama K. , Hoshino H. , Ikemoto H. 
Published: December 2003

Abstract
Neutron diffraction measurements for liquid (l-) Te have been performed. The first minimum after the first peak of g(r) is well above zero and filled up with temperature, while the second peak diminishes substantially and flattens out at high temperature. The temperature variations of g(r) are analyzed combining the structural information available from our EXAFS results. The curve fitting of g(r) for l-Te predicts that two different inter-chain components coexist. The first corresponds to the short-distance inter-chain component around 3.2Å and the second corresponds to the long-distance inter-chain component around 3.8Å. The filling of the first minimum around 3.2Å at high temperature is clearly related to the metallization. EXAFS analysis on the basis of the model g(r) indicates that the short-distance inter-chain component (P2) responsible for the metallic conduction in l-Te as well as the nearest intra-chain component (P1) are required for fitting the oscillatory spectrum in the region of short-range sensitivity of the EXAFS signal. It is concluded that the S-M transition observed for l-Te arises from the transformation to the densely packed configuration composed of shortened chain molecules.
Wetting Transitions in Fluid K
x
KCl1−

x
Revisited
Authors: Dogel S. , Nattland D. , Freyland Werner 
Published: December 2003

Abstract
Spectroscopic ellipsometry and reflectometry were employed to study the wetting behaviour of the metal–molten salt system K
x
(KCl)1−

x
at the interface to an inert sapphire wall. We present new results on the wetting film spectra and on the film thickness at solid–liquid coexistence and in the homogeneous liquid phase. The film spectra clearly show the typical absorption of the liquid state F-centre. The wetting film thickness strongly increases approaching the monotectic temperature along the liquidus line. In the homogeneous regime the film thickness decreases at constant composition with increasing temperature and at constant temperature with decreasing salt concentration in agreement with complete wetting. For the interpretation within the framework of tetra point wetting we have developed a quantitative description of the excess Gibbs energy of the system.
To the Temperature Dependence of Carbon Particle Formation in Shock Wave Pyrolysis Processes
Authors: Emelianov A. , Eremin A. , Jander H. , Wagner H. Gg. 
Published: December 2003

Abstract
In this work the results of numerous experiments on carbon particle formation in combustion and pyrolysis of various carbon bearing molecules behind shock waves in the wide temperature range from 1200K to 3500K are analyzed. It is shown, that the discrepancy in the temperatures of the maximum particle yield could be attributed to the differences in the endothermicy of the pyrolysis of various molecules and the maximum optical density at 633nm in all mixtures can be related to the same temperture T=1600K. Based on this consideration, several statements were formulated. First – particle growth in all mixtures can be described by the uniform dependence of optical density D (at 633 nm) on time D~aτ0.4 indicating, that particle formation proceeds via homogeneous condensation. The second – decrease of the optical density at 633nm with the temperature rise is caused not by the decrease of particle yield, but the decrease of their size resulting in the fall of extinction at the given wavelength. Third – the reason of the fall of the final particle size with the temperature rise is the acceleration of the initial cluster formation process and a corresponding increase of the particle number density. And the last statement – the secondary particle growth, observed at T>2200K is completely determined by the primary clusters (nucleus) formed behind the incident wave and the coagulation of small carbon particles formed behind the reflected shock wave using these clusters.
Thermal Diffusion of Weak Electrolytes: IV. Relationship between the Transported Enthalpies of the Ionic and Molecular Form of the Solute
Authors: Domonkos L. , Liszi J. 
Published: December 2003

Abstract
It is established that during the thermal diffusion of weak electrolytes in dilute aqueous solution the total transported enthalpies of the molecular and ionic form of the solute component are practically identical.
Analysis of Semiconductor Cluster Beam Polarization Taking Small Permanent Dipole Moments into Account
Authors: Schnell M. , Herwig C. , Becker J. A. 
Published: December 2003

Abstract
Deflections of semiconductor cluster beams in an inhomogeneous electric field deliver enhanced polarizabilities for cold isolated Ga
N
As
M
clusters with odd number of atoms n=N+M up to n=17. One speculated that the high polarizabilities result from their electronic open shell structure. This was qualitatively confirmed by optical absorption cross section measurements, but the enhancement of polarizability is too large to be explained through a Kramers–Kronig-relation as purely electronic effect. Moreover, quantum chemical calculations gave permanent dipole moments of some tenths of a Debye for certain compositions. The clusters are too heavy to identify these dipole moments by beam broadening effects, but we will show in the present analytic investigation within classical top theory, that a slight reversible-adiabatic alignment of the clusters dipole moment in the electric field increases the average beam deflection and the derived polarizability values. This effect was up to now not taken into account and it offers a consistent explanation of the Ga
N
As
M
polarizabilities by small permanent dipole moments of some tenths of a Debye and a reasonable rotational temperature between 2 and 12K.
Prediction of Reduced Falloff Curves for Recombination Reactions at Low Temperatures
Authors: Cobos Carlos J. , Troe Jürgen 
Published: December 2003

AbstractStrong collision falloff curves for barrierless recombination reactions at low temperatures are calculated taking into account transitional modes only. Specific rate constantsk(E,J) from statistical adiabatic channel/classical trajectory (SACM/CT) calculations are used. Broadening factors of the falloff curves are found to depend only weakly on the temperature. A systematic analysis of the influence of the centrifugal barriersE0(J), which are governed by the potential energy surface of the bond energiesE0, and of the number of transitional modes is made. Guidelines for estimating center broadening factors and shape functions for the broadening factors are given.
Phase Separation in Ultracold Boson–Fermion Mixtures under Confinement
Authors: Akdeniz Z. , Tosi M. P. 
Published: December 2003

Abstract
A short review is given of recent progress in understanding the demixing transition in a mesoscopic gaseous cloud of bosonic and fermionic alkali atoms under the effect of their mutual repulsions at zero temperature. The mixture is confined inside a magnetic trap exerting external harmonic potentials on the atoms and the bosonic component is taken in a Bose-Einstein condensed state while the fermions are in a spin-polarized state. Main emphasis is placed on the role of the confinement: in a mesoscopic system (i) the phase transition becomes smooth as a function of the driving parameter, which is the boson-fermion s-wave scattering length; and (ii) various configurations of the phase-separated gaseous cloud are allowed, including some very exotic ones in an anisotropic trap. The transition inside a spherical trap leads to an egg-type structure, with the bosonic condensate being surrounded by a shell of fermions, and is best identified from a sharp upturn of the frequency of low-lying monopolar and dipolar oscillations of fermionic character. This dynamical signature of the transition appears when the overlap between the two components has already started to decrease, but is still quite appreciable. A system of specific experimental interest is the mixture of 6Li and 7Li isotopes, whose parameters could be driven towards the phase transition.
Can Alkali Metal Doped Zeolites be Metallic? – Microwave Conductivity of Rubidium Doped Zeolite Rho
Authors: Edmondson Michael J. , Barker Peter D. , Porch Adrian , Anderson Paul A. , Edwards Peter P. 
Published: December 2003

Abstract
Large crystallites of high purity zeolite rho have been synthesized by controlled monitoring of the aging and heating period of the mother gel. The microwave conductivity of Rb-rho samples doped with up to 20Rb atoms p.u.c. was measured over the temperature range 15–300K. Confirmation that the conductivity was due to rubidium doped zeolite rho and not decomposition products or residual rubidium metal was provided by XRD, TEM, and microwave loss measurements on zeolite supported silver particles, the latter providing the first experimental confirmation of the validity of the quasistatic analysis for highly conducting particles. At low concentrations of rubidium dopant the observed microwave responses were dominated by dielectric effects. In the sample Rb17/Rb-rho, a strongly temperature-dependent electronic contribution to the conductivity was observed above ~150K. In Rb20/Rb-rho, conductivities in the range 1.5–2.3 Sm−1 were observed between 15 and 300K. The residual conductivity at 15K indicates that the sample is indeed metallic, but the values of conductivity measured are low in comparison to conventional metals.
Density Dependence of the Interrelation between Single Particle Motion and the Collective Dynamics in Liquid Sodium
Authors: Pilgrim W.-C. , Morkel C. 
Published: December 2003

Abstract
Over a wide range of densities we have systematically investigated the single particle motion in liquid sodium in a series of quasielastic neutron scattering experiments. Our experimental results are in excellent agreement with predictions from molecular dynamics simulations and Mode-Coupling-Theory. The results allow to determine the microscopic mechanisms that control the single particle motion on atomic time- and length- scale and to relate these mechanisms to the values of the macroscopic diffusion coefficient at different densities. We can clearly distinguish three different density regimes where respectively three different coupling mechanisms between diffusive motion and collective modes dominate: At high density, particle diffusion is hindered and the main contribution to forward motion of a particle comes from a coupling to longitudinal density modes; however, at slightly reduced density the motion of the particle is coupled to transverse shear modes which cause an enhancement of the diffusive motion and hence of the diffusion coefficient. Only at very low density, the system gradually returns to particle dynamics which is controlled by binary collisions as predicted by simple hard sphere theories.
Novel Ionization Mechanisms of Molecular Clusters in Ultraintense Laser Fields
Authors: Last Isidore , Jortner Joshua 
Published: December 2003

Abstract
We explore extreme multielectron ionization of (Xe)
n
molecular clusters resulting in the formation of highly charged Xe
k

+, k=8–32, ions in ultraintense laser fields (intensity I= 1016–1019 W cm−2), which is driven by a compound, sequential-parallel, inner-outer ionization mechanism. A computational and theoretical study is advanced for the three fundamental processes of electron fs dynamics, which involve the barrier suppression of inner ionization of the constituents, the formation of an energetic electron-positive ion charged plasma within the cluster and the outer ionization of unbound electrons from the cluster. New features of the formation, characteristics, response and dynamics of the electron-positive ion charged plasma in molecular clusters in ultraintense laser fields were explored, providing novel information on a transient (1–100 fs) metallic state in finite chemical systems.
The Chemical Potential of Metal Atoms in Small Particles
Authors: Schäfer Rolf 
Published: December 2003

Abstract
The chemical potential of metal atoms in isolated clusters has been investigated in dependence of cluster size by means of molecular beam experiments. For that purpose the heat of condensation, which is released during a cluster deposition experiment, is measured with novel microcalorimeters. The experimentally determined heat of condensation enables one to determine the formation enthalpies of the isolated particles. Additional temperature dependent measurements gives insight in the melting behaviour of the isolated systems. The investigations allow one to discuss the size-dependence of the chemical potential of metal atoms in small particles in comparison to predictions on the basis of a simple thermodynamic droplet model.
Intramolecular Hydrogen Bond Interaction in Selected Diols
Authors: Plass Monika , Kolbe Alfred 
Published: December 2003

AbstractSolute descriptors characterizing major interactions in solution are accessible based on quantitative structure-property relationships (QSPR). Parameters of such relationships should be additive for functional groups. Because added parameters of monools describing molecular interaction do not meet the experimentally found intermolecular interaction parameters of diols and triols, it is assumed that intramolecular hydrogen bonding is responsible for these deviations. In this paper the intramolecular interactions in several diols are illuminated by IR measurements. Particularly, the influence of intramolecular hydrogen bonding on the absorbances of the OH groups is subject of investigation. Two conclusions can be drawn from the results: The terminal OH groups, which underlie an OH–OH interaction, also change their absorbance intensity in comparison to the free OH band. Secondly, the intermolecular interaction potential is strongly affected by intramolecular hydrogen bonding. The first observation is tentatively quantified as well as the position of the equilibrium between intramolecularly bonded and free diols.
Particle Entropies and Entropy Quanta V. The P–t Uncertainty Relation
Authors: Zimmermann Herbert W. 
Published: December 2003

Abstract
We consider the temporal evolution of an isolated system of N particles from a non-equilibrium state of entropy S = S′ to the equilibrium state of maximum entropy, S = S
max, S′ ≤ S
max. The application of usual density matrix theory to the temporal development of S leads us to dS/dt = 0: The entropy S does not change in time t. Thereby it is irrelevant, whether we consider a non-equilibrium state or an equilibrium state. Consequently, the system cannot irreversibly change by entropy production dS/dt > 0 from S′ to S
max. This is a paradoxial result, which contradicts the experience. It can be traced back to the von Neumann equation, which in principle describes reversible processes and hence is unsuitable for calculating the irreversible evolution of the entropy S in time t. Each irreversible process is accompanied by a positive entropy production P = dS/dt ≥ 0 inside the system, which only vanishes in case of the equilibrium state. In order to overcome the above mentioned difficulties, we assign an operator
P
to the entropy production P, which is defined by the eigenvalue equation
P
|u〉 = P|u〉 with the state vector |u〉 of the N-particle system. There was an extensive discussion about the relation between the production of entropy P on one hand and the progression of time t on the other. Making use of this concept, we combine the operator of entropy production
P
with the time-development operator
U
(t, t
0) of the system and finally deduce the infinitesimal unitary operator
U
(t+τ,t) = 1 + (i/k)τ
P
by means of very general assumptions. Here
P
means the generator of the infinitesimal progression of time τ = t − t
0 and k the Boltzmann constant, representing the atomic entropy unit. Similarly to P we also treat the time t as an observable, defined by
t
|u〉 = t|u〉. We apply the infinitesimal time-evolution operator
U
(t+τ,t) to the operator of time
t
and finally obtain the
P
–
t
commutation relation i[
P
,
t
] = k, which is independent of τ. It shows that the operators
P
and
t
do not commute, and hence P and t are not sharply defined simultaneously. Instead we have uncertainties ΔP and Δt on measuring P and t, which are given by the P–t uncertainty relation ΔPΔt ≥ k/2. It readily allows a discussion of the evolution of the entropy S of the
isolated system in time t from S′ to S
max. Now, the irreversible steps are correctly described by the entropy production P = dS/dt > 0, while the thermal equilibrium is given by P = 0, ΔP = 0, and thus the lifetime of the equilibrium state Δt = ∞. According to the P–t uncertainty relation, the Boltzmann constant k is similarly important to the quantum thermodynamics of irreversible processes like Planck′s constant h to usual quantum mechanics.
Ultramicroelectrode Voltammetric Investigation of the Micellar Phase of Sodium Dodecyl Sulfate in Aqueous Solution
Authors: Yang Zhenyu , Zhao Jinsheng , Xie Yu , Bai Yamin , Du Zhankui , Yang Zhengyu 
Published: December 2003

Abstract
Ultramicroelectrode voltammetric measurements have been made on Sodium Dodecyl Sulfate (SDS) in aqueous solutions using K4Fe(CN)6 as the electroactive probe and H2SO4 as the supporting electrolyte. By extrapolation, the SDS micellar diffusion coefficient (D
m), hydrodynamic radius (R
m), aggregation number (n), and the molecular weight of SDS micellar in aqueous solutions at various surfactant concentrations are obtained. The partition coefficients, KD
, of the electroactive probe between micelle and water continuous phase are also estimated. The results suggest that the probe is sensitive to the surfactant concentration and reflect the changes of the structure and the hydrophobic nature of micelles.
Thermodynamic, Transport and Collision-Induced Light Scattering Data of Xenon Gas Simultaneously Fitted by an Isotropic Interatomic Potential
Authors: El-Kader M.S.A. , Taher B. M. 
Published: December 2003

Abstract
An approximate empirical isotropic interatomic potential for xenon interaction is developed by simultaneously fitting the Morse-Morse-Morse Spline van der Waals potential form to interaction second pressure virial coefficient, viscosity, thermal conductivity and depolarized interaction-induced light scattering data. Absolute zeroth and second moments of the two-body depolarized spectrum have been measured and compared with theoretical calculations using various models for the interatomic potential. In additions, vibrational energy levels, third pressure virial coefficient and self-diffusion calculated for the new potential are compared with experimental ones. The results show that it is the most accurate potentials yet reported for this system. The use of the new potential in lattice sum calculations yields good results for several properties of solid xenon.