ISSN:0005-9021    

DOI:10.1002/bbpc.19850890902

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

年代:1985

数据来源: WILEY

摘要:

AbstractInelastic neutron scattering has been applied for the first time to the study of matrix isolated species whose thermodynamically stable phase under normal conditions is the liquid. The aims of these investigations, which are complemented by far infrared studies, are to explore the aggregational behaviour of acetonitrile and the intermolecular dynamics of the respective aggregates in low temperature matrices of solid Ar and CCl4. The only aggregate observed, using a variety of different spectroscopic techniques and diverse experimental conditions, is an antiparallel dimer. In contrast to the external intermolecular modes of this aggregate, which were not accessible by vibrational spectroscopy, the internal modes could be described and assigned.

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890903

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

年代:1985

数据来源: WILEY

摘要:

AbstractPolarized single crystal absorption spectra of Ba[Pt1‐xMx(CN)4]·4H2O with M = Pd, Ni and 0 ≤x≤ 1 atT= 80 K are reported. The structure of the spectra depends on the concentrationx.This effect is interpreted by the variation of the relative concentration of different cluster

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890904

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

年代:1985

数据来源: WILEY

摘要:

AbstractPolarized single crystal absorption spectra of Mx[Pt(CN)4]·nH2O with M = Na, Sr, Ca, Ba, Mg atT= 10 K and 300 K are reported. From structural details of the spectra the energetic order of the low lying excited electronic states can be established

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890905

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

年代:1985

数据来源: WILEY

摘要:

AbstractDeuteron magnetic relaxation rates of the following isotopically substituted i‐propanols (CH3)2CHOD, (CH3)2CDOH, and (CD3)2CHOH have been measured as a function of the temperature and the frequency. Thus the present investigations were performed in the dispersion range. We have attempted to interpret these relaxation rates within the framework of the Woessner theory of internal rotation. The success was not satisfactory, the quadrupole coupling constants were smaller than expected. Proton magnetic relaxation rates of the two i‐propanols (CD3)2CDOH and (CH3)2CDOD have also been measured as a function of the temperature and the frequency. Separation of intra‐ and intermolecular contributions was performed by usual isotopic dilution technique. With the intramolecular relaxation rates again difficulties to describe internal rotation appeared. The dipole‐dipole coupling constant came out too small. The intermolecular relaxation rates could be related to intermolecular configurations fairly satisfactory, although dynamical descriptions still leaves open qu

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890906

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe complex permittivity of the following neat liquids has been measured in the frequency range from 20 MHz to 36 GHz at 20°C: (1) 2‐pyrrolidinone, (2) N‐methyl‐, (3) N‐vinyl‐, (4) N‐ethyl‐, (5) N‐cyclohexyl‐, (6) N‐benzyl‐2‐pyrrolidinone, (7) N‐methyl‐2‐piperidone and (8) N‐methyl‐caprolactam. The results can be described by one or two superimposed Debye‐type components. One component is due to rotational tumbling of single molecules. The additional component is ascribed to associates, possibly dimers, in the case of (1), but in the other cases, as far as occuring to a significant extent, that is with (

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890907

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe high fluorescence quantum yieldsϕfof most Triphenylmethane(TPM)‐dyes and carbon‐bridged TPM‐dyes in highly viscous solutions (ϕfranging from 0.3 to 0.8) decrease with increasing temperature by a factor>100, due to viscosity dependent nonradiative deactivation. The deactivation rateskrdof bridged model dyes are significantly smaller (by a factor of up to 170) as compared tokrdof the unbridged crystal violet. ‐ Application of the Twisted Intramolecular Charge Transfer (TICT)‐model to neutral and ionic TPM‐dyes yields an explanation for the different behaviour of similarly structured compounds. The influence of steric and electronic factors on various TPM‐dyes is discussed within this framework. This leads to a simple rule involving donor and acceptor properties of molecular subunits, which permits the prediction of fluorescence properties (high quantum efficiency for laser dyes or ultrafast deactivation for satur

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890908

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

年代:1985

数据来源: WILEY

摘要:

AbstractMolecular Dynamics simulations of liquid chloroform with 200 molecules in the basic cube have been performed at 295 and 325 K. The interactions were described by a rigid five‐site model with (12/6) Lennard‐Jones spheres and partial charges at the atom positions. At room temperature four simulation runs have been carried out. Three of them differ in the method with which the Coulomb forces have been truncated at the cut off distance. For the fourth one the charges have been removed in order to study their influence on the MD results. The intermolecular structure functions have been calculated from the simulation and are found in good agreement with results from an x‐ray measurement and with four out of five structure functions from neutron diffraction studies with isotopic substitution. Strong disagreement between simulation and experiment exists, however, for the six atom‐atom radial distribution functions. The origin of this discrepancy is traced back to the difference in one of the five neutron structure functions (CH37Cl3); because of the consistency of the simulation results with each other and with the other experimental data, it can be attributed to uncertainties of the neutron scattering experiment. It is also shown that the expansion of the molecular pair correlation function in terms of spherical harmonics does not converge rapidly enough for the calculation of the first five so called g‐coefficients with a sufficient degree of reliability from five neutron diffraction measurements. The self‐diffusion coefficients have been calculated for 295 and 324 K, respectively, and found in good agreement with experimental results. Rotational diffusion coefficients, the spectral densities of hindered translations and of the librations are reported. Various reorientational correlation functions have been calculated, which reproduce satisfactorily the corresponding experimental results. The MD calculations show clearly that the description of the dielectric relaxation needs a multi‐particle correlation function, whereas the far infrared absorption is due to single‐

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890909

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

年代:1985

数据来源: WILEY

摘要:

AbstractUsing the pressure jump technique, four reactions have been observed in the system BeSO4‐water‐glycol, three of which are concerned with the substitution of solvating molecules in the solvation layer of the beryllium ion by the sulfate ion: Of water, of monodentate glycol and of bidentate glycol. The fourth reaction could be attributed to the formation of a bisulfato beryllium complex. Equilibrium and rate constants for the involved reactions have been evaluated from conductivity measurements and from the kinetics. The results are compared with those obtained earlier in other solvent mixtures [1–6]: BeSO4in water glycol mixtures behaves similar as in other mixtures of hydrogen bond forming solvents (water, formamide, N‐methylformamide, methanol). The substitution rate in different solvatomers Be(H2O)i(glycol)2+4‐idepends only on the kind of solvent being substituted by the sulfate ion, and not on the specific solvatomer. However, the substitution of a bidentate solvating glycol occurs much faster than that of a monodentate one. Furthermore the formation of the bisulfato complex has not been observed in water, in water‐formamide and in water N‐methylformamide solutions, which due to their high dielectric constants form only relatively weak sulfato complexes and undetectable amounts of bisulf

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890910

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

年代:1985

数据来源: WILEY

摘要:

AbstractChemically modified electrodes are prepared by deposition of copper hexacyanoferrate (CuHCF) on glassy carbon. These electrodes are characterized by voltammetric and potentiometric measurements. After suitable conditioning they exhibit nearly Nernstian response to changes in activity of potassium or ammonium ions as well as good selectivity with respect to sodium ions. The kinetics of potassium ion exchange between the CuHCF film and aqueous solutions is studied and the diffusion coefficient of potassium ion in CuHCF is determined.

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890911

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

年代:1985

数据来源: WILEY