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  • Articles  (53)
  • 36.40.+d  (28)
  • equation of state  (25)
  • Springer  (53)
  • American Institute of Physics
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  • 1995-1999  (28)
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  • Articles  (53)
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  • 1995-1999  (28)
  • 1990-1994  (25)
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  • 1
    Electronic Resource
    Electronic Resource
    Static and dynamical distortions of helium clusters (1995)
    Springer
    The European physical journal 98 (1995), S. 421-428 
    Details
    ISSN: 1434-6036
    Keywords: 36.40.+d ; 33.70.Jg ; 67.40.Yv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We examine the effects of impurities (“doping”) and rotational excitation on the structural and energetic properties of helium clusters. Quantum Monte Carlo (QMC) techniques are used to study ground and rotationally excited states of pure and doped clusters. We use exponentially correlated wave functions and treat the molecular impurities as rigid. Whereas pure HeN show essentially monotonic decay of density from a central maximum value, addition of impurities induces local ordering of He to an extent dependent on the impurity-He binding. Rotational excitation of HeN gives rise to extremely large centrifugal distortions. The location of impurities also appears to change upon rotational excitation. The implications of these distortions on impurity spectra are discussed for SF6HeN, and compared to recent experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01338418
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  • 2
    Electronic Resource
    Electronic Resource
    CARS diagnostics of a CO2-laser pyrolytic experiment for the production of nanosized ceramic powders (1995)
    Springer
    Applied physics 61 (1995), S. 367-375 
    Details
    ISSN: 1432-0649
    Keywords: 36.40.+d ; 42.65.Dr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spatial distributions of rotational temperatures and molecular number densities of C2H2 and H2 were measured with CARS during the production of ultrafine SiC powders in a laser pyrolytic process flame. By means of a CO2 laser, the reaction gases SiH4 and C2H2 (or alternatively C2H4) are converted into SiC and H2. From the CARS measurements temperature gradients are determined between 8.8 × 105 K/m and 1.6 × 106 K/m with corresponding heating rates of 1.8 × 106 K/s and 1.3 × 106 K/s. The CARS data also allow an estimation of the gas expansion behaviour in the reaction zone. Moreover, they show that diffusive velocity components of the hydrogen in the hot reaction zone do not exceed 0.4 m/s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081537
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  • 3
    Electronic Resource
    Electronic Resource
    The dimer sputtering mechanism of Cu(001) at low bombarding energy (1992)
    Springer
    Applied physics 55 (1992), S. 364-371 
    Details
    ISSN: 1432-0630
    Keywords: 79.20.N ; 36.40.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The emission of dimers during bombardment of a Cu(001) surface by Cu atoms of 300 and 1000eV energy is studied. A molecular dynamics simulation method based on many-body potentials is employed. At 300eV bombarding energy, around 81% of the sputtered dimers originate from second-nearest neighbor sites. 58% of these are ejected in a collision sequence correlated by the projectile. These dimers lead to a second maximum in the kinetic energy distribution of emitted dimers at around 8eV, besides a maximum at 4eV. Only the latter is found at 1000eV bombarding energy. As in this case mostly next-neighbor surface atoms are sputtered, the specific emission mechanism found at 300eV is irrelevant. Finally, we show that the direction of the angular momentum of sputtered dimers is correlated with the original surface site of the dimers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324086
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  • 4
    Electronic Resource
    Electronic Resource
    Calculation of the dispersion of the third-order optical nonlinearity in C60 films (1995)
    Springer
    Applied physics 60 (1995), S. 49-55 
    Details
    ISSN: 1432-0630
    Keywords: 42.65.An ; 36.40.+d ; 31.20.Sy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Using wave functions determined from ground-state local-density calculations, we have calculated the wave-dispersed free response of the optical nonlinear polarizabilityγ (3)(−3ω;ω,ω,ω), for the C60 molecule andχ (3)(−3ω;ω,ω,ω) i.e. Third-Harmonic Generation (THG) for films using a sum-over-states approach. The influence of screening was determined by applying an external static electric field in separate selfconsistent calculations to evaluate induced dipole moments which was used to determine the static linear and nonlinear polarizabilities. The polarizabilities calculated in the static limit were used to determine an effective screening parameter which was, in turn, used together with an RPA approach to calculate screened wave-dispersed, third-order nonlinear optical properties such asγ (3)(−3ω;ω,ω,ω) andχ (3)(−3ω;ω,ω,ω). Comparing evaluated polarizabilities with experimental values we found that the non-resonant free polarizability compares well in absolute magnitude with experimental results. Inclusion of screening results in a polarizability about two orders of magnitude below the experimental values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01577612
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  • 5
    Electronic Resource
    Electronic Resource
    Oscillation of the radial distribution function (1992)
    Springer
    Journal of statistical physics 68 (1992), S. 1065-1087 
    Details
    ISSN: 1572-9613
    Keywords: Nonnegative operator ; hard-sphere model ; radial distribution function ; equation of state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We prove that the radial distribution function oscillates at low density in a system with a short-range nonnegative potential and investigate the branching of the solutions of an approximate equation of state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048885
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  • 6
    Electronic Resource
    Electronic Resource
    Application of a new selection algorithm to the development of a wide-range equation of state for refrigerant R134a (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 101-110 
    Details
    ISSN: 1572-9567
    Keywords: equation of state ; R 134a ; refrigerants ; simulated annealing ; stepwise regression ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Refrigerant R134a (1,1.1,2-tetrafuoroethane) is a leading substitute for refrigerant R12. As such, there has been worldwide activity to develop accurate wide-range equations of state for this fluid. In this study. we have developed a new selection algorithm for determining high-accuracy equations of state in the Helmholtz representation. This method combines least-squares regression analysis with simulated annealing optimization. Simulated annealing, unlike stepwise regression, allows for the controlled acceptance of random increases in the objective function. Thus, this procedure produces a computationally efficient selection algorithm which is not susceptible to the function-space local-minima problems present in a purely stepwise regression approach. Two equations are presented in this work and compared against experimental data and other high-accuracy equations of state for R134a. One equation was produced strictly by using stepwise a regression algorithm, while the other was produced using the simulated-annealing selection algorithm. In both cases the temperature dependence of the equations was restricted to have no terms whose exponents were greater than live.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438961
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  • 7
    Electronic Resource
    Electronic Resource
    Equations of state for the thermodynamic properties of R32 (difluoromethane) and R125 (pentafluoroethane) (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 79-89 
    Details
    ISSN: 1572-9567
    Keywords: difluoromethane (R32) ; equation of state ; pentafluoroethane (R125) ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermodynamic properties of difluoromethane (R32) and pentafluoroethane (R125) are expressed in terms of 32-term modified Benedict-Webb-Rubin (MBWR) equations of state. For each refrigerant, coefficients are reported for the MBWR equation and for ancillary equations used to fit the ideal-gas heat capacity and the coexisting densities and pressure along the saturation boundary. The MBWR coefficients were determined with a multiproperty fit that used the following types of experimental data: PVT: isochoric, isobaric, and saturated-liquid heal capacities; second virial coefficients; and properties at coexistence. The respective equations of stale accurately represent experimental data from 160 to 393 K and pressures to 35 MPa for R32 and from 174 to 448 K and pressures to 68 MPa for R125 with the exception of the critical regions. Both equations give reasonable results upon extrapolation to 500 K and 60 MPa. Comparisons between predicted and experimental values are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438959
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  • 8
    Electronic Resource
    Electronic Resource
    A fundamental equation of state for 1,1-difluoroethane (HFC-152a) (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 91-100 
    Details
    ISSN: 1572-9567
    Keywords: equation of state ; Helmholtz free energy ; HFC-152a ; refrigeranis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A fundamental equation ofstale for HFC-152a ( 1,1-dilluorocthane) is presented covering temperatures between the triple-point temperature ( 154.56 K) and 435 K for pressures up to 311 M Pa. The equation is based on reliable (p, g, T) data in the range mentioned above. These are generally represented within ±0.1 % of density. Furthermore. experimental values of the vapor pressure, the saturated liquid density, and some isobaric heat capacities in the liquid were included during the correlation process. The new equation of state is compared with experimental data and also with the equation of state developed by Tamatsu et al. Differences between the two equations of state generally result from using different experimental input data. It is shown that the new equation of state allows an accurate calculation of various thermodynamic properties for most technical applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438960
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of thermodynamic properties from the speed of sound (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 663-673 
    Details
    ISSN: 1572-9567
    Keywords: equation of state ; speed of sound ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe methods by which all of the observable thermodynamic properties of a compressed gas, including the compressibility factor and the isochoric heat capacity, may be determined from sound speed data by numerical integration of a pair of partial differential equations. The technique may be employed over a wide range of conditions. Initial values are required. but we demonstrate that values specified on an isotherm close to the critical temperature are sufficient for application of the method to the entire homogeneous fluid region at subcritical densities. The method may also be extended to higher densities at temperatures above the critical. The effects of errors in both the initial values and the speed of sound are examined in detail by means of analytic and numerical results. The results indicate that all of the observable thermodynamic properties may be obtained with an uncertainty equal to or less than that achievable by the best available alternative techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438851
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular simulation and theory of associating chain molecules (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 705-713 
    Details
    ISSN: 1572-9567
    Keywords: associating fluids ; chain fluids ; computer simulations ; equation of state ; hydrogen bonding ; Lennard-Jones ; Monte Carlo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A closed-form statistical mechanical based equation of state for associating chain fluids is presented. A Lennard-Jones chain is used as a reference to account for the repulsive, dispersive and anisotropic (size) contributions, while the short-range directional attraction is treated as a perturbation expansion based on Wertheim's first-order theory of associating fluids. A model fluid composed of a chain of tangently bonded Lennard-Jones spheres with an associating square-well site at one of the end spheres is studied. Isobaric-isothermal Monte Carlo simulations were performed for this model at subcritical and supercritical temperatures at a association strength typical of hydrogen-bonding systems. The theory is seen accurately to predict the simulation results subject to the limitations of the equation of state of the reference fluid. The system studied has some of the main complexities found in associating chain molecules such as organic acids, alkanols, and primary amines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438855
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  • 11
    Electronic Resource
    Electronic Resource
    Equation of state for mixtures of nonpolar fluids: Prediction from experimental constants of the components (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 1053-1060 
    Details
    ISSN: 1572-9567
    Keywords: equation of state ; gases ; mixtures ; nonpolar fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a simple procedure by which an analytical equations of state for a mixture of normal fluids can be predicted from the constantsT c (critical temperature),p c (critial pressure), and ω (Pitzer acentric factor) for each pure component. The equation covers the range from the dilute vapor or gas to the highly compressed liquid or supercritical fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01141215
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  • 12
    Electronic Resource
    Electronic Resource
    A new nonrandom lattice fluid model and its simplification by two-liquid theory for phase equilibria of complex mixtures (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 723-731 
    Details
    ISSN: 1572-9567
    Keywords: complex mixtures ; equation of state ; multiphase equilibria ; nonrandom lattice theory ; polymer solutions ; supercritical fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new riogorous equation of state (EOS) and its simplified version have been proposed by the present authors based on the full Guggenheim combinatorics ] of the nonrandom lattice hole theory. The simplified EOS. with the introduction of the concept of local composition, becomes similar to the density-dependent UNIQUAC model. However, im the present approach we have a volumetric EOS instead of the excess Gibbs function. Both EOSs were tested for their applicability in correlating the phase equilibria behavior of pure components and complex mixtures. Comparison of both models with experiment includes such systems as nonpolar nonpolar, nonpolar polar, and polar polar hydrocarbons, supercritical systems, and polymer solutions. With two parameters for each pure component and one binary interaction energy parameter, results obtained to date demonstrate that both formulations are quantitatively applicable to complex systems oer a wide range of temperatures, pressures, and concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438857
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  • 13
    Electronic Resource
    Electronic Resource
    Thermodynamic properties of the generalized Murnaghan equation of state of solids (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1009-1026 
    Details
    ISSN: 1572-9567
    Keywords: Anderson-Grüneisen ; bulk modulus ; equation of state ; expansivity ; high pressure ; Murnaghan equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the Murnaghan approximation, an isothermal relation between pressure (P) and volume (V) for solids is derived from the assumption that the isothermal bulk modulus (B) is a linear function ofP. This paper presents a thermodynamic analysis of a generalized form of the equation, based on treating all its various parameters [viz., V, B, and (∂B/∂P) T atP=0] as functions of temperature. Extending a previous study, the effect ofT upon (∂B/∂P) T is accounted for by using a dimensionless parameter introduced by us, which is used in formulating general expressions for the volume dependence of various thermophysical quantities,viz., the thermal expansion coefficient (α), the productαB, and the Grüneisen and Anderson-Grüneisen parameters. Some combinations of these parameters are identified, which show a simple dependence uponP. The new expressions are used in analyzing current approximations and the behavior of the solid in the low-compression range. In particular, an expression forα at highP is reported which generalizes the Anderson equation and previous results by us.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02093479
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  • 14
    Electronic Resource
    Electronic Resource
    Application of nonlinear regression in the development of a wide range formulation for HCFC-22 (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1155-1164 
    Details
    ISSN: 1572-9567
    Keywords: chlorodifluoromethane ; equation of state ; HCFC-22 ; nonlinear fitting ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An equation of state has been developed for HCFC-22 for temperatures from the triple point (115.73 K) to 550 K, at pressures up to 60 MPa. Based on comparisons between experimental data and calculated properties, the accuracy of the wide-range equation of state is ±0.1% in density, ±0.3% in speed of sound, and ±1.0% in isobaric heat capacity, except in the critical region. Nonlinear fitting techniques were used to fit a liquid equation of state based onP-ρ-T, speed of sound, and isobaric heat capacity data. Properties calculated from the liquid equation of state were then used to expand the range of validity of the wide range equation of state for HCFC-22.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02081283
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  • 15
    Electronic Resource
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    Vapor-liquid equilibrium, coexistence curve, and critical locus for binary HFC-32/HFC-134a mixture (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1175-1184 
    Details
    ISSN: 1572-9567
    Keywords: binary interaction parameter ; critical density ; critical temperature ; equation of state ; R-32/134a mixture ; vapor-liquid coexistence curve ; vapor-liquid equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two kinds of equilibrium measurements of binary R-32/134a mixtures were carried out. The vapor-liquid equilibria were measured by the static method in the temperature range between 283 and 313 K. On the basis of the present experimental data, the temperature dependence of the binary interaction parameterk 12 for two equations of state, namely, the Soave-Redlich-Kwong equation and Carnahan-Starling-De Santis equation, was discussed. The vapor-liquid coexistence curve near the critical point was also measured by the observation of meniscus disappearance. The critical temperatures and critical densities of 30 and 70 wt% R-32 mixtures were determined on the basis of the saturation densities along the coexistence curve in the critical region. In addition, a correlation of the critical locus for this mixture is proposed as a function of composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02081285
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  • 16
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    The use of an MHV-2 equation of state for modeling the thermodynamic properties of refrigerant mixtures (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1165-1174 
    Details
    ISSN: 1572-9567
    Keywords: activity coefficient ; equation of state ; MHV-2 ; refrigerants ; R32 ; R134a ; R125 ; vapor-liquid equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02081284
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  • 17
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    Prediction of multiphase equilibria in associating fluids by a contact-site quasichemical equation of state (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1287-1297 
    Details
    ISSN: 1572-9567
    Keywords: associating fluids ; contact-site model ; equation of state ; group contribution ; monomer fraction ; multiphase equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A contact-site quasichemical equation of state has been used Tor the modeling of different kinds of fluid phase equilibria (between a gas phase and one or more liquids) over a wide range of conditions. Among the systems of interest are the ternary mixtures water + alkanols + hydrocarbons (alkanes or alkynes), water + alkanols (or acetone)+ CO2, water + polyoxyethyleneglycol ethers + heavy alkanes. The model has been applied to describing the thermodynamic properties of the binary subsystems and to predict the phase behavior of the ternary systems. For longer-chain alkanols and hydrocarbons a group-contribution approach is implemented, which allows the modeling when no experimental data are available. The model gives reasonable predictions of phase behavior and the correct trends in the calculated phase diagrams in most cases. The concentrations of associates in liquid and gas phases are estimated by the model and compared with some experimental and computer simulation data. The predictive abilities of the model, its limitations, and possible ways of its improvement are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02081296
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  • 18
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    A New equation of state for square-well molecules (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1277-1286 
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    ISSN: 1572-9567
    Keywords: equation of state ; molecular simulation ; perturbation theory ; second virial coefficient ; square-well molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper presents a new equation of state for the square-well fluid based on perturbation theory. This equation has the exact second virial coefficient behavior, converges to the correct mean-field behavior at high densities, and accurately interpolates between the two limits. Monte Carlo simulations were performed to evaluate the limiting behavior of the theory in the dilute-gas regime. Comparison of the theory with the simulation results shows excellent agreement between the equation-of-state predictions and the data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02081295
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  • 19
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    Ideal-gas thermodynamic properties for natural-gas applications (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1381-1392 
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    ISSN: 1572-9567
    Keywords: caloric properties ; equation of state ; ideal gas ; isobaric heat capacity ; natural gas ; speed of sound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of thec p 0 correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were adjusted to selectedc p 0 data calculated from spectroscopic data for temperatures ranging from 10 to 1000 K. The data sources used are discussed and compared with literature data deduced from theoretic models and caloric measurements. The parameters presented will be applied in a current GERG project for evaluating equations of state (e.g., the AGA 8 equation) for their suitability for calculating caloric properties.
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    URL: http://dx.doi.org/10.1007/BF02083547
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  • 20
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    An analytical method of predicting Lee-Kesler-Plöcker equation-of-state binary interaction coefficients (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1393-1411 
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    ISSN: 1572-9567
    Keywords: computer algorithm ; binary interaction coefficient ; equation of state ; mixture ; nonpolar and polar substances ; thermodynamic properties ; reduced properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analytical method is proposed for finding numerical values of binary interaction coefficients for the Lee-Kesler-Plöcker (LKP) equation of state. The method is based on solving simultaneous equations from Plöcker's mixing rules for pseudocritical parameters of a mixture and the Lee-Kesler equation for the saturation line. For mixtures of hydrocarbons containing from two to nine carbon atoms, the divergence between calculated and experimentally based interaction coefficients (ICs) is no more than ±0.4%. The method is extended to mixtures of polar substances. For polar mixtures, aneffective molar composition concept is introduced which takes into account the impact of dipole moments on the process of molecular associations. Formulas for finding the effective molar composition of mixtures containing polar and/or nonpolar constituents and the binary interaction coefficient (κ ij) based on this effective composition and pure component properties are shown. Calculatedκ ij values for 12 binary mixtures of polar substances differ by 0.4 % or less from correspondingκ ij values obtained by processing experimental data on saturated pressure (P s) and saturated temperature (T s) lines for these same mixtures. A simplified alternativeκ ij approximation method with an error (2–5 %) is also given for mixtures of polar substances.
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    URL: http://dx.doi.org/10.1007/BF02083548
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  • 21
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    A corresponding-states principle for the equation of state of linear homonuclear fused-hard-sphere fluids (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1413-1419 
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    ISSN: 1572-9567
    Keywords: equation of state ; corresponding states ; fused-hard-sphere fluids ; hard spheres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A theoretically based corresponding-states principle previously developed for the equation of state of hard-convex-body fluids is extended to rigid linear homonuclear fused-hard-sphere fluids. Effective volumes and shapes are introduced in order to account for the nonconvexity of the molecules. The excess compressibility factor, reduced by means of a parameter which can be determined analytically, is a common function of the effective packing fraction. The analytical expression for the function can be obtained from the equation of state of the hard-sphere fluid. Existing simulation data for diatomics, triatomics and tetraatomics show excellent agreement with the corresponding-states principle.
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    URL: http://dx.doi.org/10.1007/BF02083549
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  • 22
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    An analytical equation of state for molten alkali metals (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1429-1438 
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    ISSN: 1572-9567
    Keywords: cohesive energy ; equation of state ; molten alkali metals ; statistical mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper brings the molten alkali metals into the scope of a new statistical mechanical equation of state that is known to satisfy normal fluids over the whole range. As for normal fluids, the latent heat of vaporization and density at freezing temperature are the only inputs (scaling factors). The correspondingstates correlation of normal fluids is used to calculate the second virial coefficient,B 2(T), of alkali metals, which is scarce experimentally and its calculation is complicated by dimer formation. Calculations of the other two temperature-dependent constants,α(T) andb(T), follow by scaling. The virial coefficients of alkali metals cannot be expected to obey a law of corresponding states for normal fluids. The fact that two potentials are involved may be the reason for this. Thus, alkali metals have the characteristics of interacting through singlet and triple potentials so that the treatment by a single potential here is fortuitous. The adjustable parameter of the equation of state,γ, compensates for the uncertainties inB 2(T). The procedure used to calculate the density of liquids Li through Cs from the freezing line up to several hundred degrees above the boiling temperatures. The results are within 5 %.
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    Shell effects in the equation of state of metals (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 315-329 
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    ISSN: 1572-9567
    Keywords: equation of state ; high pressures ; ionization ; quasiclassical approach ; Thomas-Fermi model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A simple quasiclassical Z-scaling model (QMT) is proposed to calculate the electron equation of state (EOS) for matter with a high energy concentration. This model may be employed over a wide range of densities and temperatures from the Saha model region of application to the corrected Thomas-Fermi model model (TFC) area of use. The treated model describes ab initio typical step behavior of the ionization state and energy as a result of successive shell ionization with increased temperature. The model naturally includes the effects of electron-ion interaction with increased density. This EOS model may be interesting for gas dynamics, energetics, astrophysics, etc.
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    Measurements of the virial coefficients and equation of state of the carbon dioxide+ethane system in the supercritical region (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 1011-1032 
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    ISSN: 1572-9567
    Keywords: carbon dioxide ; densities ; equation of state ; ethane ; PρT ; mixtures ; virial coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Gas-phase densities of the system carbon dioxide+ethane were measured with a Burnett apparatus at 320 K and at pressures up to approximately 10 MPa. Measurements were made on systems having carbon dioxide mole fractions of 0, 0.25166, 0.49245, 0.73978, and 1. Second and third virial coefficients were determined for each composition, and the cross virial coefficients were calculated. Comparisons were made with other recent high-quality measurements on this system. For each mixture compositionPρT measurements were made on five isochores having densities within ±30% of the critical density. Temperatures varied from 288 to 320 K. The two-phase boundary was determined and estimates are given forT c andP c for each composition.
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    Equation of state for fluid alkali metals: Binodal (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 533-543 
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    ISSN: 1572-9567
    Keywords: alkali metals ; binodal ; corresponding states ; equation of state ; fluid metals ; rectilinear diameter ; thermodynamic similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The three-parameter generalized van der Waals equation of state for liquids and gases is analyzed. This equation contains the generalized expressiona/V" for the molecular pressure: here the parametern takes into account the specificity of intermolecular attractive forces for various substances. The equation is presented in the reduced form, from which follows the single-parameter law of corresponding states with the thermodynamic similarity parametern. 11 is established that for alkali metals the value of the parameter it is the same and does not depend on temperature substantially. From the given generalized equation, the expressions for the binodal (equilibrium curve of the liquid and vapor phases) are obtained. For cesium. rubidium, and potassium, the temperature dependence of density is calculated over the temperature range from their melting point to the critical point: the results of the calculations agree with experimental data. It is established that for alkali metals, the law of rectilinear diameter breaks down in the vicinity of the critical point.
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    A thermodynamic property formulation for cyclohexane (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 519-531 
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    ISSN: 1572-9567
    Keywords: cyclohexane ; equation of state ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A formulation for the thermodynamic properties of cyclohexane is presented. The equation is valid for single-phase and saturation states from the melting line to 700 K at pressures up to 80 MPa. It includes a fundamental equation explicit in reduced Helmholtz energy with independent variables of reduced density and temperature. The functional form and coefficients of the ancillary equations were determined by weighted linear regression analyses of evaluated experimental data. An adaptive regression algorithm was used to determine the final equation. To ensure correct thermodynamic behavior of the Helmholtz energy surface the coefficients of the fundamental equation were determined with multiproperty fitting, Pressure-density-temperature (P-p-T) and isobaric heat capacity (C p -P-T) data were used to develop the fundamental equation, SaturationP-p-T values, calculated from the estimating functions, were used to ensure thermodynamic consistency at the vapor-liquid phase boundary. Separate functions were used for the vapor pressure, saturated liquid density, saturated vapor density. ideal-gas heat capacity. and pressure on the melting curve, Comparisons between experimental data and values calculated using the fundamental equation are given to verify the accuracy of the formulation. The formulation given here may be used to calculate densities within ±0.1 %, heat capacities to within ±2 %. and speed of sound to within ± 1 %, except near the critical point.
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    Thermodynamic properties of methane in the critical region (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 671-684 
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    ISSN: 1572-9567
    Keywords: coexistence curve ; critical phenomena ; equation of state ; methane ; sound velocity ; specific heat ; thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An equation of state is presented for the thermodynamic properties of methane in the vicinity of the critical point. It incorporates the scaled asymptotic critical behavior predicted theoretically and supplements a global analytic equation of state for methane recently developed by Setzmann and Wagner.
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    Describing vapor-liquid equilibria in methanol +n-alkane systems by means of an equation of state with association (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 227-236 
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    ISSN: 1572-9567
    Keywords: association ; equation of state ; false liquid-liquid split ; methanol +n-alkane systems ; mixing rule ; vapor-liquid equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ability of an equation of state incorporating association to describe vapor-liquid equilibrium of methanol +n-alkane systems has been tested. An equation of state with association is divided into “physical” and “chemical” parts, where the Patel-Teja cubic equation of state is used for the description of the physical part and an association tenn forms the chemical part. Five two- and threeparameter mixing rules were tested and compared with an equation of state without association. On the average for the first eight n-alkanes, the improvement in fit of pressure using association was 30–50 % and the calculated vapor compositions were also much improved. In addition, there were lewer points with unstable liquid phase (false liquid-liquid split). Both with and without association, density-dependent mixing rules based on a local-composition concept gave the best result.
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    The selection of international standards for the thermodynamic properties of HFC-134a and HCFC-123 (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 781-790 
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    ISSN: 1572-9567
    Keywords: environmentally acceptable refrigerants ; equation of state ; thermodynamic properties ; international standards
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    Topics: Physics
    Notes: Abstract The objectives and activities of the International Energy Agency-Annex 18 are summarized. One of the goals of the Annex was to determine the formulations that best represent the thermodynamic properties of HFC-134a and HCFC-123. The formulations selected were those which accurately represented the experimental data and simultaneously exhibited thermodynamic consistency. Methods of comparison include analysis of the experimental data, statistical comparisons of values calculated from the property formulations to experimental values, and graphical analyses of the thermodynamic surface. The analytical methods used are summarized in this paper. The equations of state reviewed in these comparisons represented the most accurate formulations available in December 1992. Four equations of state were reviewed for HFC-I34a and three equations of state were considered for HCFC-123. These equations represented the work of independent researchers in Germany, Japan, and the United States. The formulations selected as international standards are presented.
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    Pairing effects in metal clusters (1992)
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    The European physical journal 22 (1992), S. 659-666 
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    ISSN: 1434-6079
    Keywords: 74.20.Fg ; 36.40.+d
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    Topics: Physics
    Notes: Abstract Motivated by the experimental finding of oddeven alternations in the mass spectra and ionization potentials of metal clusters, we have investigated the possibility of interpreting these results as evidence for pairing correlations among the electrons. For the present exploratory calculations, we have used a spherical BCS model which we have applied, as an example, to some Al clusters. Additional model calculations have been carried out for Na N with 34〈N〈100 in order to illustrate a possible systematics.
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    Production and properties of CO2 cluster anions (1992)
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    The European physical journal 24 (1992), S. 289-296 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 35.20
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    Topics: Physics
    Notes: Abstract Stoichiometric and non-stoichiometric negatively charged CO2 cluster ions have been produced in a crossed neutral cluster/electron beam ion source. The abundance and stability of these ions have been studied with a double focussing sector field mass spectrometer. The observed abundance anomalies (“magic numbers”) in the mass spectra of (CO2) n − and (CO2) n O− ions correlate with corresponding small and large metastable fractions of these ions (for loss of one CO2 unit). Variation of the measured metastable fractions as a function ofn are related to corresponding changes in the monomer binding energies. In addition, we have observed for the first time (CO2) n O 2 − ions (i.e. at electron energies above 8 eV with an energy resonance at about 14 eV) and we discuss possible production mechanisms for these ions. Relative electron attachment cross sections have been determined in the energy regime O〈E≦20 eV for (CO2) n − , (CO2) n O− and (CO2) n O 2 − withn=1 to 20. The shape of the cross section function for (CO2) n O− is strongly dependent on the cluster sizen.
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    Cluster size effects (1992)
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    The European physical journal 24 (1992), S. 247-275 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 31.20.Ej ; 35.20-i ; 33.80.-b
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    Topics: Physics
    Notes: Abstract In this paper we address some of the unique, novel and basic features of clusters, which involve the physical and chemical consequences of their large surface/volume ratio and the size dependence of the properties of large finite systems. Energetic, quantum, electronic, spectroscopic, and electrodynamic size effects in clusters were quantified by cluster size equations (CSEs), which describe the gradual “transition” from the large finite cluster to the infinite bulk system, with increasing the cluster size. Some progress was also accomplished in the description of the “transition” from cluster microsurfaces to macrosurfaces, which can be described in terms of surface CSEs. The analysis implies a nonuniversality principle for cluster size effects, with different physical properties being described in terms of distinct CSEs. The CSEs provide a quantitative answer to a central question in the area of cluster chemical physics: What is the minimal cluster size for which its properties become size invariant and do not differ in any significant way from those of the macroscopic sample of the same material? A unified (but not universal) description is advanced for the merging between the properties of microscopic large finite systems and those of a macroscopic bulk material.
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    On the electrostatic energy of charged alkali clusters (1992)
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    The European physical journal 23 (1992), S. 269-274 
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    Keywords: 36.40.+d
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    Topics: Physics
    Notes: Abstract In the framework of the jellium model an algorithm is presented to calculate the electrostatic energy of charged metal clusters of arbitrary shape. Explicit expressions are given for some special shapes.
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    Molecular dynamics of 300 keV (D2O)100 clusters on Ti-D (1992)
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    The European physical journal 24 (1992), S. 385-394 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 52.20.Hv ; 79.20.Nc
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    Topics: Physics
    Notes: Abstract We use the molecular dynamics code DAMSEL to predict the velocity distributions for beam and lattice atoms after bombardment of Ti-D “foils” of thickness 20.86 Å by 300 keV (D2O)100 cluster ions. From these distributions we estimate the D-D nuclear fusion yield. We find that cluster bombardment reduces the overall energy deposition of the beam in the lattice compared to that of the individual beam atoms of the same velocity. However, a small portion of lattice atoms (〈1%), and a larger percentage of beam atoms (∼30%), have energies above the maximum present in the case of bombardment by individual D or O atoms. The folding of the standard D-D fusion cross sections over the relative velocity distributions produced by beam and lattice deuterons produce a fusion yield estimate of ∼1×10−21 fusions per cluster, with the high-energy distributions of beam deuterons playing the most important role. This is nine orders of magnitude lower that the data of Beuhler et al. While transient (∼10 fs) atom densities 50% higher than that of the initial lattice are recorded in the course of the simulation, the average energy transferred per lattice atom — 23 eV — is insufficient to support any “collision spike” explanation of the observed fusion yield.
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    Collision induced fragmentation of mass-selected (CO2) n + clusters (1992)
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    The European physical journal 22 (1992), S. 521-527 
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    Keywords: 36.40.+d ; 34.90.+q
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    Topics: Physics
    Notes: Abstract The collisional velocity dependence of the cross sections for fragmentation of mass-selected (CO2) n + (n+2...7) clusters in collisions with Ar atoms is presented. Interesting structure can be observed in the cross sections which indicate that the collision occurs between the Ar atom and one CO2 molecule within the cluster. The results may be explained by assuming that the collision leads to either vibrational excitation of a loosely bound CO2 monomer which then leaves the cluster or excitation of the entire cluster to a dissociative state.
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    Electronic structure calculations of small Al n (n=2–8) clusters (1992)
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    The European physical journal 22 (1992), S. 641-644 
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    Keywords: 31.20.Ej ; 36.40.+d
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    Topics: Physics
    Notes: Abstract The electronic states of small Al n (n=2–8) clusters have been calculated with a relativistic ab-initio MO-LCAO Dirac-Fock-Slater method using numerical atomic DFS wave-functions. The excitation energies were obtained from a ground state calculation of neutral clusters, and in addition from negative clusters charged by half an electron in order to account for part of the relaxation. These energies are compared with experimental photo-electron spectra.
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    Helium cluster ions RgHe x + (Rg=Ne, Ar and Kr,x≦14) formed in a drift tube cooled by liquid helium (1992)
    Springer
    The European physical journal 22 (1992), S. 645-650 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 35.20.Wg
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    Topics: Physics
    Notes: Abstract Rare gas ions Ne+, Ar+ and Kr+ are injected into a drift tube which is filled with helium gas and cooled by liquid helium. Helium cluster ions RgHe x + (Rg=Ne, Ar and Kr,x≦14) are observed as products. Information regarding the stability of RgHe x + is obtained from drift field dependence of the size distribution of the clusters, and magic numbers are determined. The magic numbers arex=11 and 13 for NeHe x + andx=12 for ArHe x + and KrHe x + . NeHe x + , Ar+ and Kr+ are proposed as the core ions for NeHe 13 + , ArHe 12 + and KrHe 12 + , respectively.
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    Ab-initio study of localization of an excess electron in sodium halide clusters (1992)
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    The European physical journal 23 (1992), S. 91-98 
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    Keywords: 31.20.Di ; 31.20.Ej ; 31.90.+s ; 36.40.+d
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    Topics: Physics
    Notes: Abstract The equilibrium geometries of Na n F n and Na n F n−1 are optimized forn=2, 3, 4 at the SCF level. The Na n F n molecules appear as formed by Na+ and F− ions. The paper studies the localization of the excess electron in the Na n F n−1 molecules. Na n F n−1 is obtained by removing from Na n F n a fluorine atom, and the excess electron takes the place of this lacking center, and allows a weak bond between the neighbouring Na atoms. Secondary minimum geometries, for which the excess electron has no defined place, are also studied.
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    Ab initio calculation of the vertical excitation energies of small helium cluster ions (1992)
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    The European physical journal 22 (1992), S. 741-745 
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    ISSN: 1434-6079
    Keywords: 31.20.Tz ; 33.20.Lg ; 36.40.+d
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    Topics: Physics
    Notes: Abstract Quantum chemical ab initio calculations have been performed for the vertical excitation energies and oscillator strengths of all low-lying electronically excited states of small helium cluster ions, He n + ,n=2, ..., 7. The geometrical structures of the ions were fixed at the equilibrium geometries of the respective ground states, for He 4 + and He 5 + also one alternative structure was considered. The low-lying excited states can be classified into two categories: the electronic transition can occur either within the central He 2 + or He 3 + unit or from the peripheral weakly bound He atoms to this unit. The latter transitions are very weak (f≈0.001), closely spaced, with vertical excitation energies of about 5.7 eV. The He 2 + and He 3 + units have strong transitions at 9.93 and 5.55 eV, respectively; these transitions are only slightly blue-shifted if He 2 + or He 3 + are placed as “chromophores” into the centre of a larger He n + cluster. The large difference in the vertical excitation energy of the strong transition should enable an experimental decision of the question whether the cluster ions have He 2 + or He 3 + cores.
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    Effects of surface roughness on the electronic structure of metallic clusters (1992)
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    The European physical journal 24 (1992), S. 57-63 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 31.20.Pv ; 05.40.+j
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    Topics: Physics
    Notes: Abstract We study the electronic level density in spherical clusters. Due to the granularity of the ionic background the surface is irregular at the microscopical level. We show that this affects the shell structure and that the level statistics display from the bottom to the top of the spectrum a transition from a poissonian behaviour to one consistent with the predictions of random matrices theory.
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    Infrared molecular beam depletion spectroscopy of size-selected methanol clusters (1992)
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    The European physical journal 24 (1992), S. 277-287 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 33.20.Ea
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    Topics: Physics
    Notes: Abstract Molecular beam depletion spectroscopy has been employed to study the dissociation of small methanol clusters in the spectral region between 1000 and 1100 cm−1 which covers thev 8 CO stretch (1033.5 cm−1) and thev 7 CH3 rock (1074.5 cm−1) monomer vibrations. Size selection has been achieved by dispersing the (CH3OH) n cluster beam by a secondary He beam. Aside from the recently published CH3OH dimer absorption bands at 1026.5 and 1051.6 cm−1 which are assigned to the excitation of the CO stretching vibrations in the non-equivalent subunits of the hydrogen-bonded complex, a previously unobserved band was found at 1071.3 cm−1. This absorption band is attributed to the excitation of the CH3 rocking vibration in the dimer. It appears that this transition which is very weak in the free methanol monomer receives substantial oscillator strength due to the intermolecular interaction in the complex. A splitting of this band could not be observed. The trimer and tetramer spectra feature single peaks for the CO stretching vibration being centered at 1042.2 cm−1 and 1044.0 cm−1, respectively. This observation is consistent with the cyclic structures of these species. The trimer and tetramer rocking vibrations are observed near 1060.5 cm−1 but cannot be localized exactly, due to a gap in the CO2 laser tuning range.
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    Mechanisms of anion formation in O2, O2/Ar and O2/Ne clusters; the role of inelastic electron scattering (1992)
    Springer
    The European physical journal 25 (1992), S. 77-85 
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    ISSN: 1434-6079
    Keywords: 34.70.+e ; 34.80.Gs ; 36.40.+d ; 34.80.−i
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    Topics: Physics
    Notes: Abstract Measurements are reported on the formation of negative ions in O2, O2/Ar and O2/Ne clusters aimed at establishing the mechanisms of anion formation and the role of inelastic electron scattering by the cluster constituents on negative ion formation in clusters. In the case of pure O2 clusters the main anions we detected are of two types: O−(O2) n≧0 and (O2) n ≧1− . The yields of O−(O2) n showed maxima at 6.3, 8.0 and ∼14.0 eV and the data suggest O− as their precursor; the maxima at 8 and ∼14 eV are due to the production of O− via symmetry forbidden dissociative attachment processes in O2 at these energies which become allowed in clusters. The yields of (O2) n − showed a strong maximum at near-zero energy (∼0.5 eV) and also at 6.3, 8 and ∼14 eV. With the exception of the near-zero energy resonance, the (O2) n − anions at 6.3, 8 and ∼14 eV are attributed to nondissociative attachment of near-zero energy “secondary” electrons to O2 clusters. The slow secondary electrons result predominantly from scattering via the O 2 − negative ion states of incident electrons with energies in their respective regions. Similar results were obtained for the mixed O2/rare gas clusters except that now a feeble and distinctly structured contribution in the yields of O−(O2) n , (O2) n − (and Ar(O2) n − ) was observed at energies 〉10 eV. These anions are believed to have the lowest negative ion states of Ar*− (Ne*−) as their precursors.
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    Theoretical study of the 4f photoemission spectrum in Au55 aggregates (1995)
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    The European physical journal 32 (1995), S. 337-341 
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    ISSN: 1434-6079
    Keywords: 36.40.+d ; 79.60.−i ; 36.20.Kd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the photoemission process of a core level electron a satellite structure may appear due to the simultaneous excitations of valence electrons (many-electron effects). We study this phenomenon in Au55 aggregates. In this calculation we assume that the excitations can be limited to the 6s electrons which are described by means of tight-binding Hamiltonians in the initial (no core hole) and the final (hole present on a core level) states. An extension of a Anderson's formula strictly valid for the bulk is discussed and the possible use of the phase shift concept is analyzed. Our calculated satellite structure depends only on two parameters: Δ, the core hole attractive diagonal term and β, the normal transfer integral. We fix Δ/β=3 by comparison of our results to experiment performed on Au55 (P Ph3)12Cl6 compounds. The various experimental features are roughly reproduced by the calculation (number of peaks as well as their intensities and positions). Another interpretation of the experimental structure was proposed in the original experimental work. A more extensive investigation on other polyhedral metallic aggregates is necessary for allowing a choice between the two models.
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    Direct temperature measurement in alkali halide cluster beam (1995)
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    The European physical journal 34 (1995), S. 135-138 
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    ISSN: 1434-6079
    Keywords: 71.50.+t ; 36.40.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The temperature of a sodium fluoride cluster beam produced by laser vaporization is estimated from the rotationally-resolved laser spectroscopy of the Na2 dimer. The cluster beam is obtained by laser vaporization of a sodium rod in a mixture of helium containing a small amount (1%) of SF6. Both rotational and vibrational temperatures (respectively 170 K and 400 K) are much higher than expected from a simple theoretical model of a supersonic beam. These temperatures can be lowered to 70 K and 250 K respectively by cooling the nozzle to liquid nitrogen temperature.
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    URL: http://dx.doi.org/10.1007/BF01439388
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  • 45
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    Theory for the atomic shell structure of the cluster magnetic moment and magnetoresistance of a cluster ensemble (1995)
    Springer
    The European physical journal 35 (1995), S. 273-278 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 72.15.Gd ; 75.30.Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a simple theory for the cluster size dependence of the average cluster magnetic moment of transition metal clusters. Assuming a local environmental dependence of the atomic magnetic moments, the cluster magnetization exhibits a magnetic shell structure, reflecting the atomic structure of the cluster. Thus, the observed oscillations of the average cluster magnet moment may serve as a fingerprint of the cluster geometry. We also discuss the giant magnetoresistance (GMR) exhibited by an ensemble of magnetic clusters embedded in a metallic matrix. It is shown that the magnetic anisotropy affects strongly the magnetization of the cluster ensemble under certain conditions. Since the GMR depends on the cluster ensemble magnetization, it can be used to determine the cluster magnetic anisotropy energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01745530
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    Photoionization studies of free sodium ammonia clusters (1992)
    Springer
    The European physical journal 22 (1992), S. 651-658 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 33.80.Eh ; 82.40.Dm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Free sodium ammonia clusters Na(NH3) n up ton=45 were generated in a pickup source by injecting a beam of neutral sodium atoms into the expansion zone of a piezo driven pulsed nozzle. The clusters thus formed are studied by one-photon ionisation in the region of 266 nm to 520 nm, time-of-flight mass spectrometry as well as photoelectron spectrometry. Ionisation thresholds for clusters up ton=18 and dissociation energies for the neutral Na(NH3) n up ton=6 are reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426368
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  • 47
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    Sub-picosecond laser ionization of free C60 and C70 at 248 nm (1992)
    Springer
    The European physical journal 23 (1992), S. 195-196 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 33.80.Rv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Delayed ionization is found to be absent for sub-picosecond laser excitation of free C60 and C70 at 248 nm. The autocorrelation trace obtained for C 60 + in a laser time-of-flight (TOF) mass spectrometer using two time-delayed and collinear 248 nm ultrashort laser pulses has a width of 1.1 ps (715 fs for sech2 pulses), in agreement with the laser pulse duration measurement in NO gas. Both above observations can be explained by direct ionization of C60 via coherent two-photon absorption by the high intensity sub-picosecond 248 nm laser excitation avoiding the channel leading to delayed ionization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437394
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  • 48
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    Electron impact ionization of silver clusters Ag n ,n≦36 (1992)
    Springer
    The European physical journal 22 (1992), S. 517-520 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron impact ionization of gas phase silver clusters Ag n ,n≦36 has been achieved in the threshold region. The vertical ionization potentials in this region clearly demonstrate the evidence of shell effects as well as a distinct even-odd oscillation up ton≃20. Their general size dependence is somewhat different from that of the alkali metal clusters due to the presence of thed-electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426093
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  • 49
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    Resonant two-photon two-color photoionization (R2P2CI) spectra of aniline-Ar n clusters: Isomer strutures and solvent shifts (1992)
    Springer
    The European physical journal 22 (1992), S. 529-539 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 35.20.Vf ; 33.80.Eh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present resonant two-photon two-color photoionization (R2P2CI) spectra of a series of Aniline-Ar n complexes (n=1−6). An apparently anomalous blue shifted spectra for An-Ar3 is explained by a modified spectral shift additivity rule which assigns different shifts to different relative positions of the Ar with respect to aniline. Evidence is presented for the existence of several isomers of clusters withn≧2. It is shown that, by changing the nucleation conditions, it is possible to control the relative populations of the various isomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426095
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  • 50
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    Distribution of interatomic distances in large metallic clusters (1992)
    Springer
    The European physical journal 22 (1992), S. 541-545 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 61.50.Cj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spherically averaged pseudopotential (SAPS) calculations have been done for Mg n clusters, withn up to 250 within the framework of density functional theory. The electronic structure is computed resorting to the Thomas-Fermi-Dirac-Weizsäcker (TFDW) approximation for the kinetic energy. The equilibrium geometries have been obtained by minimizing the total cluster energy with respect to the atomic positions using the steepest-descent method. The ground state geometries obtained in this way are formed by spherical atomic shells, the number of them increasing with cluster size, up to a number of four for the biggest sizes considered here. An analysis of the distribution of the interatomic distances shows that the more internal is the shell, the more contracted are the interatomic distances. This effect diminishes progressively with increasing cluster size. For the purpose of comparison, similar calculations have been done with Cs n clusters in the same size range, allowing us to reproduce previous results obtained using a more elaborated density functional technique (Kohn-Sham method). The inhomogeneous contraction of interatomic distances then appears as a general fact for simple metallic clusters and not only for alkaline ones.
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    URL: http://dx.doi.org/10.1007/BF01426096
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    Simulation of cluster impact fusion (1992)
    Springer
    The European physical journal 22 (1992), S. 547-551 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 79.20.Rf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report molecular dynamics simulations of the impact of TiD clusters on TiD targets. In each cluster collision the total fusion probability seems to be due to a single deuterium deuterium collision. The kinetic energies of incident deuterium atoms gradually level off around the initial cluster energy, but do not reach the high energy tail of a corresponding Maxwell-Boltzmann distribution. Neither any other support for a thermonuclear fusion mechanism was observed. On the contrary, our simulations imply that the enhanced fusion rate is rather due to channeled many atom collision cascade type mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426097
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  • 52
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    Ionic core effects on the mie resonance in lithium clusters (1995)
    Springer
    The European physical journal 32 (1995), S. 329-336 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 78.20.−e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the effects of the atomic cores on the Mie resonance in lithium metal clusters, perturbing a jellium Hamiltonian with zero-range pseudopotentials. The resonance is red-shifted with respect to the classical formula by core effects, most important of which is the increased effective mass due to the core potentials. Much of the large shift seen in lithium clusters is thereby explained if the strength of the pseudopotentials is taken from band structure calculations. However, such pseudopotentials cause the resonance to be greatly broadened, contrary to observation.
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    URL: http://dx.doi.org/10.1007/BF01437277
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    Mass distribution of cluster ions produced from laser ablation of metal-composite-oxides Y-M-Cu-O (M=Ba, Sr, Ca, Mg) (1995)
    Springer
    The European physical journal 34 (1995), S. 257-261 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 35.20.Wg ; 34.10.+x
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Laser ablation of YMCuO metal-composite-oxides (M=Ba, Sr, Ca, Mg) in high vacuum produced cluster ions with various sizes and compositions. Mass spectra of the cluster ions were recorded by a home-built time-of-flight (TOF) mass spectrometer and the mass distributions were analyzed by a statistical model. For YBa2Cu3O7−x (YBCO) high-Tc superconducting samples, six series of cluster ions were observed. Replacement of barium in the metal-composite-oxide sample with other alkaline earth metal, such as strontium, calcium, or magnesium, not only removed the superconductivity, but also changed the compositions and distributions of the laser generated cluster ions. For instance, copper was only found in the compositions of cluster ions generated from YBCO sample. From comparison of the experimental results, interactions among components of the metal-composite-oxides and the function of alkaline earth metal in superconducting material were discussed.
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    URL: http://dx.doi.org/10.1007/BF01437571
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