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Dr. Safak Bulut Dr. Philipp Eiden Witali Beichel Dr. John M. Slattery Dr. Tom F. Beyersdorff Dr. Thomas J. S. Schubert Prof. Dr. Ingo Krossing 《Chemphyschem》2011,12(12):2296-2310
A series of bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) with classical as well as mildly functionalized cations was prepared and their viscosities and conductivities were determined as a function of the temperature. Both were analyzed with respect to Arrhenius, Litovitz and Vogel–Fulcher–Tammann (VFT) behaviors, as well as in the context of their molecular volume (Vm). Their viscosity and conductivity are highly correlated with Vm/T or related expressions (R2≥0.94). With the knowledge of Vm of new cations, these correlations allow the temperature‐dependent prediction of the viscosity and conductivity of hitherto unknown, non‐ or mildly functionalized ILs with low error bars (0.05 and 0.04 log units, respectively). The influence of the cation structure and mild functionalization on the physical properties was studied with systematically altered cations, in which Vm remained similar. The To parameter obtained from the VFT fits was compared to the experimental glass temperature (Tg) and the Tg/To ratio for each IL was calculated using both experimental values and Angell’s relationship. With Walden plots we investigated the IL ionicity and interpreted it in relation to the cation effects on the physical IL properties. We checked the validity of these Vm/T relations by also including the recently published variable temperature viscosity and conductivity data of the [Al(ORF)4]? ILs with RF=C(H)(CF3)2 (error bars for the prediction: 0.09 and 0.10 log units, respectively). 相似文献
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Dipl.‐Chem. Tobias Köchner Dr. Sebastian Riedel Dipl.‐Chem. Anna J. Lehner Dr. Harald Scherer Dr. Ines Raabe Tobias A. Engesser Dipl.‐Chem. Franziska W. Scholz Dipl.‐Chem. Urs Gellrich Dipl.‐Chem. Philipp Eiden Dipl.‐Chem. Roberto A. Paz Schmidt Prof. Dr. Dietmar A. Plattner Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2010,49(44):8139-8143
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Fritz Eiden 《Chemie in Unserer Zeit》2007,41(4):316-323
Carl Hagemann (1867–1940), well known for his collection of German Expressionist paintings, was a successful chemist and manager at Farbenfabriken Bayer, Cassella and IG Farben company. 1893 he described a simple method of synthesizing methyl‐cyclohexenone‐carboxylic acid ethylesters, one is connected with the author's name to “Hagemann's ester”. It and many derivatives are used for synthesizing natural products and pharmaceuticals. Surprisingly, the Hagemann painting collection survived the spiteful actions of Hitler's regime and the dangerous Allied bombing raids and moreover today's chemists are still interested in Hagemann's ester. 相似文献
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Charles J. Barinaga Gregory C. Eiden Michael L. Alexander D. W. Koppenaal 《Fresenius' Journal of Analytical Chemistry》1996,355(5-6):487-493
Investigations using ion trap devices for analytical atomic spectroscopy purposes have focused on the use of an inductively coupled plasma (ICP) ion source with ion trap mass spectrometric (ITMS) detection. Initial studies were conducted with an instrument assembled by simply appending an ion trap as the detector to a fairly conventional ICP/MS instrument, i.e. leaving an intermediate linear quadrupole between the plasma source and the ion trap. The principal advantages found with this system include the destruction of nearly all problematic and typical ICP/MS polyatomic ions (e.g., ArH+, ArO+, ArCl+, Ar2+, etc) and a dramatic reduction of the primary plasma source ion, Ar+. These results prompted the development of a second-generation plasma source ion trap instrument in which direct coupling of the ICP and ion trap has been effected (i.e. no intermediate linear quadrupole); the same performance benefits have been largely preserved. Initial operation of this instrument is described, characterized, and compared to the originally described ICP/ITMS and conventional ICP/MS systems. In addition, experiments aimed at improving ICP/ITMS sensitivity and selectivity using broadband resonance excitation techniques are described. Finally, the potential for laser optical detection of trapped ions for analytical purposes is speculated upon. 相似文献
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Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Sch?ler 《Fresenius' Journal of Analytical Chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for
the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight. 相似文献
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G. C. Eiden C. J. Barinaga D. W. Koppenaal 《Journal of the American Society for Mass Spectrometry》1996,7(11):1161-1171
An experimental study of resonant ion excitation in an rf quadrupole ion trap is reported. Atomic ions are generated in an inductively coupled plasma and injected into the ion trap where, after collisional cooling, they are irradiated by a low-voltage, dipole coupled waveform. Single frequency, narrowband, and broadband excitation pulses have been used. Absorption lineshapes (plots of observed ion signal versus excitation frequency) are shown for variations in buffer gas pressure and the amplitude and duration of the single frequency pulses. The absorption lineshapes are usually asymmetric and tail toward lower frequencies. At sufficiently low buffer gas pressure or potential well depth, the lineshapes broaden and become more asymmetric to the point that absorption by ions with adjacent mass-to-charge ratios overlaps. This overlapping absorption reduces the selectivity with which a single mass-to-charge ratio ion can be excited and ejected relative to nearby mass-to-charge ratio ions. The rate of ion ejection is different on the low versus high frequency edges of the absorption lines. This difference in ejection rates provides an important key to understanding the shape of the absorption lines. All of these observations are explained in terms of the known kinematic behavior of ions in real traps, that is, traps with substantial higher order symmetry components in the trapping field (“nonlinear” fields). The importance of the nonlinearity of the trapping field in understanding the observed lineshapes and their time dependencies is discussed. We also report resonant ejection results obtained using multiple frequency (narrow or broad bandwidth) excitation. Multiple frequency excitation allows ions with different mass-to-charge ratio values to be ejected from the trap using one excitation waveform. The finite ion storage capacity of the ion trap is thereby reserved for the ion(s) of interest. We show that ejection of 89Y ions can be ~ 105 times more efficient than ejection of ions at either m/z 88 or 90. 相似文献