ISSN:0005-9021    

DOI:10.1002/bbpc.19830870503

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe relaxation times characterizing the growth or decay of small perturbations from a stationary‐state established under continuous‐flow, well‐stirred conditions are derived for the autocatalytic sequences A +nB → (n+ 1) B, withn= 1 or 2. The results show how as the flow‐rate is varied, relaxation times may gradually become very long compared with the mean residence‐time of the system. This lengthening is accompanied by a change in the mathematical form, from an exponential to an inverse dependence on time. This is not, however, a critical phenomenon, nor are infinite valu

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870504

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe photochemistry of the di‐deuterated benzenes has been examined in the vapour phase over the wavelength range of 245 to 270 nm. The sensitized emission of biacetyl technique was used to obtain the triplet yields. The sums of the singlet and triplet yields for all three molecules were found to be unity between 255 and 265 nm. – Phosphorescence lifetimes in EPA and methylcyclohexane glasses have been recorded and found to be non‐exponential. – Mechanisms consistent with the experimental observations are presented and various rate constants have been e

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870505

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

年代:1983

数据来源: WILEY

摘要:

AbstractAfter irradiation of liquid cyclohexane with 0.5 ns electron pulses time resolved emission from the cyclohexane singlet state (RH(S1)) was observed. From the decrease of the cyclohexane fluorescence lifetime by adding solutes (S) as alkanes, alkenes and aromatics rate constants of the energy transfer reaction\documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {{\rm RH}({\rm S}^1) + {\rm S} \to {\rm S}({\rm S}^1) + {\rm RH}}&{(1)} \\ \end{array} $\end{document}were determined. The rate constants of reaction (1) showed a pronounced dependence on the zero‐zero singlet energy difference ΔEof the donor acceptor pair. Thisk1vs. ΔEdependence is explained in terms of changes in the Franck‐Condon vibrational overlap factors as well as by a classical model according to Rehm and Welle

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870506

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

年代:1983

数据来源: WILEY

摘要:

AbstractBased on experimental evidence from UV‐absorption and emission, transient UV‐absorption (laser flash photolysis), and light induced changes in NMR‐spectra, the electronic relaxation pathways of 2‐(2‐pyridinyl)‐1‐(3‐pyridinyl)‐ethanone are discussed, including proton transfer and isomerisation in both the excited state and the ground state. It is found that the relaxation mechanism is dependent on the s

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870507

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

年代:1983

数据来源: WILEY

摘要:

AbstractAn anomalous red‐shift of the FIR‐absorption band of CH3CN in n‐heptane with increasing temperature had been reported in Ref. [1]. This result is experimentally confirmed. We also observed the same effect in some other solvents (CCl4, CS2, and cyclohexane). In the case of n‐heptane the temperature dependence of the overall absorption intensity attains a maximum within the temperature range under examination. The theoretical interpretation of the anomalous red‐shift as given in previous papers is

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870508

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe quantum efficiency of dye sensitization at polycrystalline SnO2thin films can reach a high value close to ϕ = 1 if determined immediately after preparation, however it slowly drops down to low values (ϕ ∼ 0.01) after inserting the electrode into aqueous electrolyte solutions. The quantum efficiency decay rate depends on the electrolyte composition. Capacitance and cyclic voltammetry measurements indicate the formation of an insulating layer. Auger‐ and IR‐reflection spectra have been used to identify this layer as a mixed oxide/hydroxide formed by hydrolysis of the surface oxide. This layer acts as an energy barrier for the injection current from the excited dye molecule thus decreasing the sensitization quantum eff

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870509

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe reaction of H2O, H2O2, and NH3with an excess of F‐atoms was investigated in an isothermal flow system. The following rate constants were obtained\documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {k1({\rm F} + {\rm H}_2 {\rm O}) = (2.5 \pm 0.6) \cdot 10^{13} {\rm exp}\left({ - \frac{{(400 \pm 70){\rm K}}}{T}} \right)\frac{{{\rm cm}^3 }}{{{\rm mol s}}}243

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870510

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe absorption and desorption kinetics of H2is calculated for a system where dissociation or recombination of H2molecules and permeation of H atoms through a surface layer are the rate determining steps of the reaction. The model yield rate laws ν(T, x), time lawsx(t, T), and their dependence onp, T, andx.Two parameters introduced determine where simple equations for the limiting cases of surface or permeation control hold and where more complex relations for the transition region with two partial reactions as rate determining steps are valid. As rate laws for absorption ν ∝︁pnwith 0.5

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870511

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe mobility of hydrogen in cold‐rolled palladium specimens of different degree of plastic deformation was measured by employing the tritium tracer method. – In one set of experiments the temperature dependence of the diffusivity was determined at very low hydrogen to metal ratios below about 10−5. In another set of experiments the influence of precharged hydrogen on the tritium mobility was investigated at constant temperature. – The diffusion of tritium as a tracer in presence of hydrogen and within an imperfect lattice is treated on the assumption of local isotope distribution equilibrium between traps and interstitial sites. A trap binding energy of about 18 kJmol−1is obtained. – By means of a self‐consistent evaluation of the experimental data also the trap binding entropy, the concentration of traps, and the separation factor of the isotope distribution equilibrium is determined. – It is found that tritium is enriched in interstitial positions. The concentration of traps is doubled on going from 30% to 50% of deformation. The localized vibrations of tritium in trap sites are found to be distinctly softer than in interstitial positions. – We suggest dislocation cores and sites close to dislocation cores as operating traps. The interaction energy between hydrogen and dislocation traps is discussed in connection with the misfit energy of h

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870512

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

年代:1983

数据来源: WILEY