ISSN:0005-9021    

DOI:10.1002/bbpc.199500049

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.199500051

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.199500053

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractIR absorption spectroscopy of HF clusters in synchronized pulsed supersonic jet expansions and at thermal equilibrium is combined with a 1 +2 + 3 body decomposition scheme of the potential energy surfaces, different quantum chemical approaches and multidimensional vibrational quantum Monte Carlo calculations to characterize all major constituents (HF)n(n= 1–8) of the strongly associated HF vapor phase in terms of their structure, spectra, energetics, dynamics and abundance. From this data base, a microscopic quantum statistical model of HF vapor up to moderate pressures is constructed. Comparison to existing bulk thermodynamic data confirms that the model provides a globally correct and detailed microscopic description of this unique association phenomenon together with its explanatio

ISSN:0005-9021    

DOI:10.1002/bbpc.199500055

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe structure of liquid Chloroform at 298 K is determined with Reverse Monte Carlo simulations. Three independent neutron and one X‐ray scattering experiments are fitted simultaneously to obtain higher evidence in the structural results. The structure is described in form of atom pair correlation and angular distribution functions. Furthermore, the atom pair correlation functions are used to calculate a probability that gives the spatial correlation of atoms of neighbouring molecules around a center molecule. The results are compared with Molecular Dynamics simulations of chloroform from literature and a very good agreement between both methods is found. The aim to reproduce experimental results with statistical mechanical calculations based on site‐site Ornstein Zernike (SSOZ or R1SM) theory in combination with the HNC closure fails. The comparison between statistical mechanical calculations and simulations reveals the unability of the SSOZ theory to describe the short range order of liquid chloroform. SSOZ theory predicts correlations of the hydrogen atom at short distances which clearly are not possible in the real liq

ISSN:0005-9021    

DOI:10.1002/bbpc.199500056

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe isobaric thermal expansivities (αp) of n‐hexane and of methane measured over large pressure and temperature ranges have been proposed as a thermodynamic property test for theoretical and semi‐empirical equations of state for simple liquids at high densities. The correlation equations for αp(p, T) and the coordinates of the crossing point of isotherms of αpare given for both substances. A number of selected equations of state with various modifications of the attractive and repulsive contribution to the pressure have been tested with respect to their ability to reproduce the proposed test property. The analysis has revealed that at high densities the equations of state with modified repulsive term reproduce the test property better than the equations with modified attractive term. A reproduction of the most characteristic feature of the test property, the crossing of isotherms of αpcan be only obtained with equations in which the repulsion term is made softer than the simple rigid‐sphere termR T/(Vm–b). The best reproduction of the test property was obtained with the soft‐sphere equation constructed on 8–4 Lennard‐Jones intermolecular pair potential. The anisotropy in molecular shape of n‐hexane and methane has only a little influence on the

ISSN:0005-9021    

DOI:10.1002/bbpc.199500057

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractNonlinear dielectric effect (NDE) was measured in mixtures of 1,3‐dimethoxybenzene with n‐alkanes. The mixtures were found to exhibit an apparent critical point, concealed below the melting point of the mixture and manifesting itself by anomalous NDE behaviour in the vicinity of the critical concentrations in the stable liquid ph

ISSN:0005-9021    

DOI:10.1002/bbpc.199500058

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe alkali‐excess system [M13X12]+and the corresponding excess‐electron cluster M13X12are studied with ab initio methods. Selected reaction energies of cationic alkali‐excess clusters, especially of [M23X22]+, are reported using results for the stoichiometric cluster M10X10and a comparison between sodium chloride and lithium fluoride is presented. Finally, a fully internal anion defect and an edge defect location are investigated for the clusters [Na14Cl12]2+and [Na14Cl12]+, to resolve previous discrepancies in the liter

ISSN:0005-9021    

DOI:10.1002/bbpc.199500059

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on theVolterraintegral technique, a universal method to calculate the sorption uptake curves of multi‐component gas mixtures in porous solids under variable high pressure conditions with non‐ideal behavior of the gas phase has been proposed. It takes into account a non‐linearly behaving concentration dependence at the surface of the porous medium. The applicability of the introduced method presupposes an isothermic gas phase and a constant diffusivity matrix. For the description of the non‐ideal gas phase behavior, equations of state were u

ISSN:0005-9021    

DOI:10.1002/bbpc.199500060

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe UV absorption cross sections of acetyl peroxynitrate (PAN) and trifluoroacetyl peroxynitrate (FPAN) were determined at 298 K in the wavelength ranges 220–325 nm and 230–305 nm, respectively. Both peroxynitrates were prepared from nitric acid and the corresponding peroxy acids in n‐tridecane solution. The UV spectra were measured in a large cell (v= 420 dm3) equipped with White mirror systems for the simultaneous detection of gas phase species by long‐path UV and IR absorption. Impurities in the samples were quantified by their IR and/or UV absorption, and the UV spectra were corrected for contributions from these impurities using appropriate reference spectra. Concentrations of acetyl peroxynitrate and trifluoroacetyl peroxynitrate were derived from their IR absorptions by application of Beer's law. IR absorption coefficients were determined based on pressure measurements of the pure compound (for PAN) or on the stoichiometric CO2yield in the thermal decomposition of the peroxynitrate in the presence of NO and O2(for FPAN). The resulting UV absorption cross sections of PAN are larger than literature values, leading to photolysis rate constants on the Earth's surface which are higher by a factor of 4 than previous values (Senum et al., 1984). The absorption cross sections of FPAN were measured for the first time and result in photolysis rate constants which are slightly higher than those of PAN, suggesting that CF3C(O)O2NO2and, by analogy, other haloacetyl peroxynitrates have too short a lifetime in the upper troposphere to be of importance for the transport of halogens into the strat

ISSN:0005-9021    

DOI:10.1002/bbpc.199500061

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY