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21.
Hermanspahn N Haffner H Kluge H Quint W Stahl S Verdu J Werth G 《Physical review letters》2000,84(3):427-430
We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus. 相似文献
22.
Yu. A. Litvinov F. Attallah K. Beckert F. Bosch M. Falch B. Franzke H. Geissel M. Hausmann Th. Kerscher O. Klepper H.-J. Kluge C. Kozhuharov K. E. G. Löbner G. Münzenberg F. Nolden Yu. N. Novikov Z. Patyk W. Quint T. Radon C. Scheidenberger M. Steck L. Vermeeren H. Wollnik 《Hyperfine Interactions》2001,132(1-4):281-287
Projectile fragments of a 209Bi beam were separated in flight with the fragment separator FRS and injected into the experimental storage ring ESR. In the
ESR a beam containing up to about 100 different isotopes was cooled to a relative velocity spread of δv/v=10−6 by means of the electron cooler. The image currents of the ions induced in a Schottky pick-up probe at each turn were recorded.
A subsequent Fast Fourier Transformation of these signals yields the revolution frequencies of the different isotopes stored
in the ESR. Unknown masses of more than 150 neutron-deficient nuclides in the element range of 52≤Z≤85 have been measured directly by Schottky Mass Spectrometry and in addition more than 60 new masses have been obtained from
α-decay chains. These new mass data allow the location of the one-proton dripline and the prediction of the two-proton dripline
for heavy nuclides. The experimental masses are compared with different theoretical predictions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
23.
Literature published in the last decade concerning the use of mid-infrared spectrometry as a detection system in separation techniques employing a liquid mobile phase is reviewed. In addition to the continued use of isocratic liquid chromatographic (LC) techniques, advances in chemometric data evaluation techniques now allow the use of gradient techniques on a routine basis, thus significantly broadening the range of possible applications of LC-IR. The general trend towards miniaturized separation systems was also followed for mid-IR detection where two key developments are of special importance. Firstly, concerning on-line detection the advent of micro-fabricated flow-cells with inner volumes of only a few nL for transmission as well as attenuated total reflection measurements enabled on-line mid-IR detection in capillary LC and opened the path for the first successful realization of on-line mid-IR detection in capillary zone electrophoresis as well as micellar electrokinetic chromatography. Secondly, concerning off-line detection the use of micro-flow through dispensers now enables to concentrate eluting analytes on dried spots sized a few tens of micrometers, thus matching the dimensions for sensitive detection by mid-IR microscopy. Finally in an attempt to increase detection sensitivity of on-line mid-IR detection, mid-IR quantum cascade lasers have been used. Applications cover the field of food analysis, environmental analysis and the characterization of explosives among others. Best detection sensitivities for on-line and off-line detection have been achieved in miniaturized systems and are in the order of 50 ng and 2 ng on column, respectively. 相似文献
24.
Julia Kuligowski Guillermo Quintás Salvador Garrigues Miguel de la Guardia 《Chromatographia》2010,72(3-4):201-202
On-line gel permeation chromatography Fourier transform infrared (GPC-FTIR) is proposed as detection technique for the determination of the total polymer triacylglyceride (PTG) content in olive oil as an alternative to other conventional detectors such as the evaporative light scattering detector (ELSD) or the refraction index detector (RID). FTIR detection allowed confirmation additionally to quantification of the analytes via their characteristic infrared spectra. For the extraction of chromatograms, a multivariate method called science based calibration (SBC) was used. The SBC method employed a reference spectrum of triacylglycerides (TG) extracted from the injection of a fresh olive oil sample and data obtained from a blank injection as ‘noise’ matrix, to estimate a regression vector subsequently used to predict the relative concentration of the analyte during the GPC run. Results found evidenced that the use of SBC improved the selectivity, sensitivity and repeatability of the GPC-FTIR measurements as compared to the ‘classical’ approach based on the measurement of the spectral area in a defined spectral range. The developed method provided a limit of detection for PTGs of 0.19 mg mL?1, which corresponds to a 0.65% w/w for an oil sample mass of 300 mg. 相似文献
25.
G. Astray A. Cid J. A. Manso J. C. Mejuto O. Moldes J. Morales J. Quintás 《Journal of solution chemistry》2011,40(12):2072-2081
Aggregation numbers of micelles based on N-alkylamines and mixed systems CTACl/N-alkylamines have been determined using fluorescence
techniques. The values of aggregation number are compared as a function of hydrocarbon chain length and as a function of the
molar fraction in the mixed systems. 相似文献
26.
27.
A model was developed to simulate permeability decrease induced by hydrodynamic effects when injecting a fluid in a reservoir with respect to particle release and capture mechanisms and the parameters of the fluid–rock system. The kinetics of particle release and capture were integrated after computing the initial permeability of the porous medium with a square lattice of a two–dimensional network model. The rate of particle release is related to the difference between a microscopic velocity of the fluid and a critical velocity. The permeability decrease shows a direct link to the reduction of pore throat radii by three mechanisms of particle capture: straining and particle accumulation through direct interception or diffusion. Comparison between the simulations and the experimental results shows that the model reproduces the physics of the permeability decrease phenomenon, although the values are overestimated. The difference between the two sets of results can be explained by the fact that the simulations are realized at constant pressure whereas the experiments are realized at constant flow rate, and that re–entrainment of the trapped particles was not taken into account in the model. 相似文献
28.
Jean-Francois Bisson Hideki Yagi Takakimi Yanagitani Alexander Kaminskii Yuri N. Barabanenkov Ken-Ichi Ueda 《Optical Review》2007,14(1):1-13
Grain boundaries play a key role in determining several key properties of polycrystalline laser ceramics. Heat transfer measurements
at low temperature constitute a good tool to probe grain boundaries. We review the results of heat transfer measurements in
polycrystalline Y3Al5O12 garnets as well as Y2O3 and Lu2O3 sesquioxide materials obtained by self-energy-driven sintering of nano-particles. The average phonon mean free path in Y3Al5O12 was found to be significantly larger than the average grain size and to scale with temperature as T
−2 at low temperature. Existing models describing the interaction between phonons and grain boundaries are reviewed. Correct
temperature dependence of the mean free path and order of magnitude of scattering rates were found by assuming the existence
of a grain boundary layer having acoustic properties different from those of the bulk. A different temperature dependence
of phonon mean free path was found for the sesquioxides and was ascribed to the stronger elastic anisotropy of these materials.
The thermal resistance associated to the grain boundaries of laser ceramics was found to be lower than in other dense polycrystalline
ceramic materials reported in the literature. 相似文献
29.
30.
Jean-Francois Le Borgne 《Journal of organometallic chemistry》1976,122(2):129-137
The condensation of metallated aldimines, prepared from activated lithium dialkylamides, with different dihalogenoalkenes gives aldehydes with a halogenovinylic group. Acidic hydrolysis of these aldehydes leads directly to cyclopentenones. When treated with an excess of activated amide, halogenovinylic aldimines give γ-acetylenic aldehydes. 相似文献