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91.
Dynamics of Methanol in Ionic Liquids: Validity of the Stokes–Einstein and Stokes–Einstein–Debye Relations 下载免费PDF全文
Elisabeth Herold Matthias Strauch Dr. Dirk Michalik Andreas Appelhagen Prof. Dr. Ralf Ludwig 《Chemphyschem》2014,15(14):3040-3048
The validity of Stokes–Einstein (SE) and Stokes–Einstein–Debye (SED) relations for methanol in the physical environment of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide is studied by means of nuclear magnetic resonance (NMR) relaxation time experiments, viscosity measurements and molecular dynamics (MD) simulations. The reorientational correlation times of the hydroxyl groups of pure methanol and of methanol in the IL/methanol mixtures were determined. For that purpose an approach for estimating NMR deuteron quadrupole coupling constants, presented by Wendt and Farrar (Mol. Phys. 1998 , 95, 1077–1081), was confirmed. The self‐diffusion coefficients of methanol were taken from the MD simulations. The viscosities of all systems were then measured and the SE and SED relations validated. For pure methanol both relations are valid, whereas they become increasingly invalid with increasing IL concentration, as indicated by effective volumes and radii that are too low. The deviation from the SE and SED relations could be related to dynamical heterogeneities described by the non‐Gaussian parameter α(t) obtained from MD simulations. For pure methanol, α(t) is close to zero in accord with the validity of both relations. With increasing IL concentration the dynamical heterogeneities of methanol increase strongly. The times t* at the maximum of α(t) increase linearly with the relative number of methanol monomers in the mixtures. Thus, the dynamical heterogeneities are largest for single methanol molecules fully embedded in the IL environment. In their own environment methanol molecules are highly mobile, whereas in the IL‐rich region the mobility is strongly reduced leading to the non‐validity of SE and SED relations. 相似文献
92.
93.
94.
J. Herold 《Fresenius' Journal of Analytical Chemistry》1940,120(7-8):292-293
Ohne Zusammenfassung 相似文献
95.
Peter Mohr Motoo Tori Peter Grossen Peter Herold Christoph Tamm 《Helvetica chimica acta》1982,65(5):1412-1417
The title compounds have been synthesized starting from verrucarol and diacetoxyscripenol (anguidine), (E, Z)-muconic half ester and a derivative of verrucarinic acid. The latter has been prepared in optically active form from dimethyl 3-methylglutarate. 相似文献
96.
Es wird eine Analysenmethode beschrieben, die es gestagttet, geringe Mengen an Sauerstoff auf Oberflāchen quantitativ nachzuweisen. Grundlage der Methode ist die Kernreaktion 18O (p. α) 15N. Die Anzahl der bei dieser Kernreaktion “prompt” emittierten α-Teilchen ist ein Maβ fūr die Sauerstoffkonzentration auf der untersuchten Probenoberfläche. Die vorliegende Arbeit be faβt sich mit der Anwendung der Methoden auf die Korrosionsforschung. In Abhängigikeit von der korosiven Belastung kann der Sauerstoffgehalt dünner Oxidschichten (1 nm – 1 μm) an technisch interessanten Matyerialien bestimmt werden. Die experimentellen Einzelheiten des Verfahrens werden beschrieben. Die zur quantitativen Auswertung benötigten Gleichungen werden abgeleitet, und es wird die Nachweisgrenze abgeschātzt. Als Anwendungsbeispiel wird die thermische Oxydation von Nickel angeführt, für die sich unter den Versuchsbedingungen in guter Übereinstimmung mit der Literature ein logarithmisches Zeitgesetz ergibt. 相似文献
97.
We prove the Marcinkiewicz–Zygmund Strong Law of Large Numbers for U-statistics of strictly stationary, absolutely regular observations (ξi)i≥1. Under suitable moment conditions and conditions on the mixing rate, we show that for some γ≥0, in the non-degenerate case, and in the degenerate case. 相似文献
98.
A study of the metastable spectra from ethoxytrimethylsilane and the mass shifts of the deuterium-labeled species permitted the rationalization of the fragmentation mechanism for forming all major ions in the mass spectrum. A new mechanistic pathway for the formation of [Si(CH3)3]+ (m/z 73) is demonstrated. A strong metastable ion for elimination of neutral acetaldehyde from the parent ion was observed despite the absence of a detectable daughter ion. 相似文献
99.
Svetlana Borovkova Robert Burton Herold Dehling 《Transactions of the American Mathematical Society》2001,353(11):4261-4318
In this paper we develop a general approach for investigating the asymptotic distribution of functionals of absolutely regular stochastic processes . Such functionals occur naturally as orbits of chaotic dynamical systems, and thus our results can be used to study probabilistic aspects of dynamical systems. We first prove some moment inequalities that are analogous to those for mixing sequences. With their help, several limit theorems can be proved in a rather straightforward manner. We illustrate this by re-proving a central limit theorem of Ibragimov and Linnik. Then we apply our techniques to -statistics
with symmetric kernel . We prove a law of large numbers, extending results of Aaronson, Burton, Dehling, Gilat, Hill and Weiss for absolutely regular processes. We also prove a central limit theorem under a different set of conditions than the known results of Denker and Keller. As our main application, we establish an invariance principle for -processes , indexed by some class of functions. We finally apply these results to study the asymptotic distribution of estimators of the fractal dimension of the attractor of a dynamical system.
100.
B. Herold und K. H. Droege 《Fresenius' Journal of Analytical Chemistry》1978,289(4):285-286
Ohne Zusammenfassung
Determination of trimethyltin compounds in dimethylthindi(isooctylthioglycolate)相似文献