Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Implementation of a dual linear image sensor for measurements of transient absorption spectra in the picosecond time regime (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2504-2507 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to enhance the picosecond absorption spectroscopy, a dual linear image sensor was used for simultaneous intensity measurements of the probing and reference lights by a single polychromator. This detector enabled us to record a fairly well stabilized transient absorption spectrum, and its signal-to-noise (S/N) ratio was much improved. Although the base line spectrum (not averaged) recorded by using a broadband continuum (a self-phase modulation light generated by focusing the fundamental light pulse from a ruby laser into a BK-7 glass block) revealed that the base line fluctuation and drift were less than ±0.04 absorbance units, the five-times spectral average gave rise to the base line fluctuation and drift of less than ±0.01 absorbance units. For an absorption spectrum recorded at a slit width of ≤0.2 mm, the spectral resolution was found to be better than that recorded by a commercial spectrophotometer with a bandwidth of 1.0 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143911
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Construction of a convenient multiple-purpose spectrophotometer system for measurements of the emission (and/or its excitation) and absorption spectra at a temperature ranging from 10 up to 313 K (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 876-882 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to enhance research in the field of low-temperature photophysics or photochemistry, a convenient multiple-purpose spectrophotometer system was constructed. This system enabled us to measure the emission (and/or its excitation) and absorption (even under steady-state photolysis) spectra of liquid and solid samples at a temperature ranging from 10 up to 313 K. The spectral resolutions (or the peak separations) were estimated to be ∼0.10–0.31 and ∼1.0–7.3 nm for an emission and its excitation spectra, respectively, recorded at a slit width between 0.05 and 0.5 mm. For an absorption spectrum recorded at a slit width of 0.5 mm, the resolution was still better than that recorded by a commercial spectrophotometer with a bandwidth of 0.2 nm. By recording a number of emission spectra (normalized by the excitation-light intensities at various excitation wavelengths), a contour mapping for the simultaneous intensity representation of the emission and its excitation spectra was also possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144136
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Dielectric friction theory of the viscosity of electrolyte solutions (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 7312-7317 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The B coefficient of the Jones–Dole equation for the viscosity of electrolyte solutions is calculated theoretically in the framework of the sphere-in-continuum model. For this purpose, the Hubbard–Onsager electrohydrodynamic equation, where the coupling of the viscous and dielectric frictions are fully taken into account, is numerically solved. The resultant B coefficients are always larger than those given by the well-known Einstein theory. The present theory is compared with the early dielectric friction theory by Clark. In methanol, our results show better agreement with experiment. In water, however, the limitations of the applied continuum model are recognized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451370
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Test of Hubbard–Onsager's dielectric friction theory for ion migration in mixed solvents. I. Ethanol–water systems (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 2776-2782 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to test the Hubbard–Onsager (HO) dielectric friction theory for ion mobility in mixtures of polar solvents, the theory has been generalized within the same framework to a system which has two dielectric relaxation times by using the superimposed Debye polarization fields related to the two kinds of dipoles. The same form of linear differential equation for the determination of the velocity field is reached only with the modified definition of the HO radius. The numerical solutions to the differential equation are fitted to a polynomial to facilitate a systematic application of the HO theory. The HO theory is reasonably well successful in predicting the dependence of the residual friction coefficient Δζ (=ζ−4πηR) on ion size and solvent composition for the alkali metal and halide ions even if no effects of the ions on solvent properties are taken into account. It turns out that the HO theory is by far better than the Zwanzig theory. Limitations of the HO theory combined with bulk properties of solvent are exhibited for the relatively large ions, in particular, below the solvent composition where the solvent has a maximum viscosity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450834
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effect of dielectric friction on the viscosity B coefficient for electrolyte in methanol–water mixture (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 5734-5738 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The viscosity B coefficient for electrolyte solution is obtained in a convenient analytical form on the basis of the Hubbard–Onsager electrohydrodynamic equation. Our dielectric friction theory is successful in predicting the general increase in the B coefficient for the small ion like Li+ with increasing the methanol content in the methanol–water mixture; the early dielectric friction theory by Clark predicts too sharp a rise and the Einstein theory, which completely neglects the dielectric friction, predicts no solvent effect. As limitations of the continuum model, our theory cannot explain the minimum of the B coefficients obtained for the larger ions in the water-rich region as well as their negative values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452500
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Test of Hubbard–Onsager–Felderhof's dielectric friction theory for ion rotation in solution (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 4654-4659 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Hubbard–Onsager–Felderhof's (HOF) dielectric friction theory for rotational motion of ions is tested by using NMR orientational relaxation times recently measured for such polyatomic ions as ClO−4,SO2−4,PO3−4, etc. in D2O and CD3OD at infinite dilution. The HOF theory combined with the bulk solvent properties is qualitatively successful in explaining how rotational friction coefficients for ions with a high surface charge density depend on ion size and valence, temperature, and solvent. In the case of a low surface charge density, the continuum model shows its inherent limitations in the treatment of ion dynamics, rotational or translational. It turns out that the HOF theory serves an important theoretical framework for the interpretation of the semiempirical relation between orientational relaxation times of ions and the solvent viscosity divided by temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451762
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Test of Hubbard–Onsager's dielectric friction theory for ion migration in mixed solvents. II. Dioxane–water systems (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 6979-6983 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Hubbard–Onsager's (HO) dielectric friction theory for the limiting ionic conductance is tested for various monovalent ions in solvent mixtures of dioxane and water by taking the residual friction coefficient which is defined as the overall friction coefficient subtracted by the Stokes friction coefficient for slip. The HO theory combined with the bulk solvent properties is successful in predicting the ion size and solvent composition dependencies of the residual friction coefficients Δζ for the alkali metal and halide ions except in the dioxane-rich region. The HO theory works much better than the early dielectric friction theory by Zwanzig because the effect of the coupling of the viscous and dielectric frictions on the velocity field is neglected in the latter theory. It turns out that the HO theory serves an important theoretical framework for the interpretation of the limiting ionic conductances experimentally obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450618
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Hydrodynamic interactions and concentration dependence of orientational relaxation times of ions in dilute solution (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 386-391 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We derived a theoretical expression for the limiting concentration dependence of ionic rotational friction coefficients using the approximations of point force and point torque and a form of hydrodynamic interaction between a pair of ions, the central ion rotating and the neighbor one translating or rotating. The pairwise hydrodynamic interactions were calculated by the reflection method and summed over all the surrounding ions in solution using the ionic distribution function due to the Debye–Hückel theory. Ionic rotational friction coefficients are predicted to increase linearly with concentration in dilute enough solution; the slope is determined by the translation rather than rotation of the countercation. The limiting slope increases with an increase in the surface charge density of the countercation if the charge effect on the cation friction coefficient is taken into account. The continuum theory has been applied to aqueous MNO3 solutions (M=Li, Na, K, Cs) at 25 °C for comparison with experiment; the theoretical predictions are in qualitative agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456485
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Effect of relaxation of ionic atmosphere on the short-time dynamics of diffusion-controlled reaction (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 7323-7329 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effect of the relaxation of the ionic atmosphere on the rate of diffusion-controlled reaction at short times was investigated. The generalized diffusion equation, in which the time-dependent friction is taken into account, was solved numerically together with the radiation boundary condition to predict the short-time behavior of the rate constant of an encounter reaction between a neutral target molecule at rest and migrating ions. The time-dependent friction kernel for a moving ion was assumed to be given as the sum of the δ function one and the Debye–Falkenhagen one where the effect of the relaxation of the ionic atmosphere was taken into account. The resultant rate constant is larger at short times than that for the time-independent friction; this prediction is in qualitative agreement with experiment. Other types of friction kernel examined could not account for experiment; the rate constant for the Gaussian kernel is smaller at short times than that for the time-independent friction, while the exponential kernel behaves in the same manner as that of the time-independent friction at all times. When the intrinsic reaction constant at the reaction radius becomes small, the effect of the time-dependent friction vanishes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458217
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The effect of dielectric friction on the viscosity B coefficient for electrolytes. Temperature dependence (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5015-5019 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We tested the dielectric friction theory of the viscosity B coefficient for the ion in solutions which was derived using the Hubbard–Onsager electrohydrodynamic equation. The temperature dependence of the B values for some monovalent ions in water, methanol, formamide, and N-methylacetamide was examined using the literature values. The theory predicts that there is almost no temperature dependence of B. However, most of the observed B values in the nonaqueous solvents decrease with increasing temperature. The B values for medium-sized ions (such as I−) in water increase with increasing temperature. These observations cannot be explained by the theory. This result lends support to the popular idea that the sign of the temperature coefficient of B can be used as a measure of the structural effect of the ion in water. The parallelism between electrolyte viscosity and conductance is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455645
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...