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1.
Laser light is used for two-step photoionization of Na2. the first step depends on the moleculer orientation, the second step doesnot. This yields a method for the analysis of molecular alignment. 相似文献
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G. Grünefeld H. Schlüter P. Andresen E. W. Rothe 《Applied physics. B, Lasers and optics》1996,62(3):241-247
A commercial tunable excimer laser consists of an oscillator-amplifier combination. The oscillator produces high-quality light that is sent to the amplifier and is distributed throughout the amplifier cavity via Cassegrain optics. We describe here two alternative approaches, a single-pass configuration for use with KrF and a triple-pass configuration with ArF, both of which do away with the Cassegrain optics. In each approach, the beam energy is the same as with Cassegrain optics. For KrF, the changes provide better locking, a higher degree of linear polarization, and a better spatial beam homogeneity, but a poorer beam divergence. For ArF, there is also better beam homogeneity, but the locking efficiency and divergence are not as good as with Cassegrain optics. 相似文献
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Sub-micrometer-sized anionic polystyrene latices have been coated with uniform layers of iron compounds by aging, at elevated temperature, dispersions of the polymer colloid in the presence of aqueous solutions of ferric chloride, urea, hydrochloric acid, and polyvinylpyrrolidone. The thickness of the deposited layers could be altered by suitable adjustment of the reactant concentrations, and they could also be increased by further aging of the coated particles in the presence of aqueous solutions of ferric chloride. Hollow colloidal spheres of iron compounds were obtained by calcination of the so-coated polystyrene latices at elevated temperature in air. Different chemical compositions of hollow colloidal spheres were obtained by heating them in hydrogen. Copyright 2000 Academic Press. 相似文献
7.
G M Rothe 《Electrophoresis》1988,9(7):307-316
Molecular mass, Stoke's radius, frictional coefficient and isomer-type of non-denatured proteins can be obtained by time-dependent gradient gel electrophoresis by evaluating the resulting data using a two-step mathematical procedure. Provided a histochemical staining procedure is available to locate the position of an enzyme in the gel, crude cell extracts can be used for estimating their molecular size properties. The computation of molecular properties of non-denatured proteins is demonstrated for isozymes of aspartate aminotransferase (EC 2.6.1.1), peroxidase (EC 1.11.1.42) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) from current-year needles of spruce. The resulting data as well as those which were calculated for esterase (EC 3.1.1.1), glutamate dehydrogenase (EC 1.4.1.4), isocitrate dehydrogenase (EC 1.4.1.42), and shikimate dehydrogenase (EC 1.1.1.25) are in accordance with those reported in the literature. The method described may be applied to various scientific areas such as genetics or environmental pollution. It could be shown here that current-year needles of injured spruce (damage class 3) contained two more peroxidase isozymes and one more glucose-6-phosphate dehydrogenase isozyme than those from non-injured trees. These differences may mark two genotypes of spruce of different susceptibilities towards present-day air and soil pollutants. 相似文献
8.
Walther C Rothe J Fuss M Büchner S Koltsov S Bergmann T 《Analytical and bioanalytical chemistry》2007,388(2):409-431
Polynuclear species of zirconium in acidic aqueous solution are investigated by combining X-ray absorption spectroscopy (XAFS)
and nanoelectrospray mass spectrometry (ESI-MS). Species distributions are measured between pHC 0 and pHC 3 for [Zr] = 1.5–10 mM. While the monomer remains a minor species, with increasing pH the degree of polymerization increases
and the formation of tetramers, pentamers, octamers, and larger polymers is observed. The high resolution of the mass spectrometer
permits the unambiguous determination of polynuclear zirconium hydroxide complexes by means of their isotopic patterns. The
relative abundances of mononuclear and polynuclear species present simultaneously in solution are measured, even if one of
the species contributes only 0.1% of the Zr concentration. For the first time it has been directly observed that the hydrolysis
of polynuclear Zr species is a continuous process which leads to charge compensation through the sequential substitution of
water molecules by hydroxide ligands until doubly charged polymers dominate at conditions (H+ and Zr concentrations) close to the solubility of Zr(OH)4(am). The invasiveness of the electrospray process was minimized by using very mild declustering conditions, leaving the polynuclear
species within a solvent shell of approximately 20 water molecules.
Figure Schematic Diagram of Multiplexed Measurement of 9 Anti-Nuclear Antibodies Using the AtheNa Multilyte Assay 相似文献
9.
J. Rothe J. Pollmann R. Franke J. Hormes H. Bönnemann W. Brijoux K. Siepen J. Richter 《Fresenius' Journal of Analytical Chemistry》1996,355(3-4):372-374
Transition metal colloids are potential precursors of heterogeneous catalysts with application to selective chemical reactions. Sample preparation techniques are described. Experimental details are given of the characterization of these often air-sensitive particles by X-ray photoelectron and X-ray absorption spectroscopy. First results obtained with both techniques for a Rh-colloid show that the metal is mainly present in the zerovalent chemical state. But the spectra indicate further chemical states of Rh which can be assigned to the outermost metal atoms of the colloid interacting with organic ligands or to the educt Rh-halides. 相似文献
10.
M. Trautmann K. W. Rothe J. Wanner H. Walther 《Applied physics. B, Lasers and optics》1981,24(1):49-53
This paper describes a new method for the determination of the deuterium content in water samples. The absorption of the radiation
of a cw deuterium fluoride laser by HDO in water vapor is measured by means of a nonresonant spectrophone (optoacoustic detector).
This method enables one to evaluate the isotope ratio of hydrogen in a rather simple and straightforward way. Advantage is
taken of the fact that HDO absorbs some of the DF laser lines whereas H2O shows no absorption. Due to the small concentration in natural water deuterium is practically entirely present as HDO. Therefore
a selective determination of the deuterium content is possible. In the course of the investigation the absorption coefficients
of HDO for the different laser lines were determined. It was thereby established that there exists a strong coincidence of
an HDO absorption line with the 2P2 DF laser line. The detection sensitivity of the method was then examined for some selected laser lines. The concentration
of HDO in natural water samples could be determined with an accuracy of better than 10%. The experiments, however, show that
with appropriate improvements it should be possible to achieve an accuracy of better than 1%. This makes the method very interesting
as an analytical tool in hydrology. 相似文献