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31.
H. Krause H. J. Neusser 《Journal of photochemistry and photobiology. A, Chemistry》1994,80(1-3):73-83
Delayed pulsed-field ionization of long-lived high Rydberg states yields vibrationally and partly rotationally resolved spectra of polyatomic molecular ions and of cluster ions when the resulting threshold ions are measured as a function of the excitation energy. The field ionized threshold ions are monitored and separated from the non-energy-selected ions in a reflecting field mass spectrometer with high mass resolution. The decay of the molecular or cluster ion core is monitored by the appearance of threshold ions at the daughter ion mass as a function of the selectively excited vibrational state. In this way, upper limits for dissociation thresholds of neutral and ionized dimers are obtained which are smaller than recent theoretical values from the literature. The appearance of daughter fragment ions after delayed pulsed-field ionization indicates that high Rydberg orbits are not destroyed by the dissociation of the core. Possible applications of our technique for the production of state-selected ions are discussed. 相似文献
32.
A. Krause M. Uhlemann A. Gebert L. Schultz 《Journal of Solid State Electrochemistry》2007,11(6):679-685
The present work demonstrates the possibilities and the limits of the in situ electrochemical scanning tunneling microscopy
for investigation of nucleation processes in magnetic fields on the examples of Cu and Co electrodeposition onto Au(111) electrodes
from sulfate electrolytes with pH 3. Cyclic voltammograms of Cu in the underpotential range (UPD) exhibit no significant change
in the cathodic and anodic peaks recorded in magnetic fields parallel to the surface. In magnetic fields of a permanent magnet,
the reconstruction of Au has been annihilated during UPD of Cu. In the overpotential range, the dissolution of Cu is inhibited.
This triggers the formation of a Cu–Au surface alloy. The UPD deposition of Co onto Au(111) could be proven without magnetic
field, which leads to the formation of two monolayers. The nucleation in an applied field could not be observed due to higher
induced fluctuations and microconvective effects.
Contribution to special issue “Magnetic field effects in Electrochemistry”. 相似文献
33.
Relative quantification of erythropoietin receptor-dependent phosphoproteins using in-gel 18O-labeling and tandem mass spectrometry 总被引:2,自引:0,他引:2
Körbel S Schümann M Bittorf T Krause E 《Rapid communications in mass spectrometry : RCM》2005,19(16):2259-2271
On examining different proteomics approaches for the investigation of structure-function relationships of erythropoietin (EPO) receptor signaling, it was found that two-dimensional gel electrophoresis/mass spectrometry procedures are clearly limited in their ability to detect low-expressed signaling proteins. Instead it was found that a strategy involving anti-phosphotyrosine immunoprecipitation, one-dimensional gel electrophoresis (1DE), and capillary liquid chromatography/tandem mass spectrometry (LC/MS/MS) provides the sensitivity required for identification of signaling proteins. In the present work the immunoprecipitation/1DE/LC/MS approach was combined with an in-gel 18O-labeling technique to analyze EPO receptor-dependent proteins. Identification and relative quantification of more than 180 EPO receptor-dependent proteins were achieved directly based on the in-gel 18O-labeling approach. 相似文献
34.
Kraus M Janek K Bienert M Krause E 《Rapid communications in mass spectrometry : RCM》2000,14(13):1094-1104
The self-assembly of beta-sheet peptide domains resulting in the formation of fibrillar aggregates (amyloids) is a feature of various neurodegenerative disorders. In order to evaluate mass spectrometric methods for the characterization of intermolecular beta-sheet structures the hydrogen/deuterium exchange behaviour of model peptides DPKGDPKG-(VT)(n)-GKGDPKPD-amide (n = 3,4,5,6,7,8), (VT)(n)-peptides, composed of a central beta-sheet-forming domain and N- and C-terminal nonstructured octapeptide sequences, was measured by electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The kinetic analysis of the hydrogen/deuterium exchange (HX) shows that intermolecular beta-sheet structures contain slowly exchanging protons (k =0.001 1/min). Localization of beta-sheet domains was achieved by monitoring the hydrogen exchange of peptide fragments generated via collision-induced dissociation (CID) or post source decay (PSD). The hydrogen exchange kinetics and the beta-sheet domains determined by ESI- and MALDI-MS were found to correlate with the length and stability of the beta-structure domain of the (VT)(n)-peptides. 相似文献
35.
We report simulations of laser-driven many-electron dynamics by means of the time-dependent configuration interaction singles (doubles) approach. The method accounts for the correlation of ground and excited states, is capable of describing explicitly time-dependent, nonlinear phenomena, and is systematically improvable. Lithium cyanide serves as a molecular test system in which the charge distribution and hence the dipole moment are shown to be switchable, in a controlled fashion, by (a series of) laser pulses which induce selective, state-to-state electronic transitions. One focus of our time-dependent calculations is the question of how fast the transition from the ionic ground state to a specific excited state that is embedded in a multitude of other states can be made, without creating an electronic wave packet. 相似文献
36.
37.
In contrast to the N-heterocyclic carbene (NHC) 1, the homologous N-heterocyclic silylene (NHS) 4 acts as a bridging ligand to Pd(0), giving rise to the dinuclear complex 5 which is catalytically active in Suzuki reactions. 相似文献
38.
Markus Follmann Nils Griebenow Michael G. Hahn Ingo Hartung Franz‐Josef Mais Joachim Mittendorf Martina Schfer Hartmut Schirok Johannes‐Peter Stasch Friederike Stoll Alexander Straub Peter Jeschke Ralf Nauen Michael Edmund Beck Hans‐Wilhelm Engels Hans‐Georg Pirkl Reinhard Albers Rolf W. Albach Jens Krause Andreas Hoffmann Holger Casselmann Jeff Dormish 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(36):9503-9503
39.
Ingolf Kahle Stefan Krause Cornelius Krasselt Alexander Jakob Alexander Oehlke Colin Georgi Steffen Schulze Heinrich Lang Michael Hietschold Stefan Spange Christian von Borczyskowski 《Applied Physics A: Materials Science & Processing》2014,115(2):617-625
Optical properties of nanomaterials such as semiconductor and metal quantum dots are important for sensors and photovoltaic applications. We report on optical, microscopic, and AFM investigations on bulk and single nanoobjects such as metal and semiconducting nanoparticles. Firstly, of special interest is the investigation of Ag metal nanoaggregates formed in zeolites. Here, the defined structure of the zeolite serves both as size directing and a stabilizing agent. The size selected Ag aggregates fluoresce in the zeolite cages even after storage under ambient conditions for almost one year. In addition, single Ag particles escape the cages and can be investigated by fluorescence microscopy also with respect to sensor applications. Secondly, with respect to photovoltaic applications, energy transfer among organic dye molecules and semiconductor quantum dots is of great importance. We report on the extension of the optical absorption of ZnSe quantum dots into the UV regime and investigate excitation energy transfer within self-assembled nanoaggregates of surface functionalized QDs and fluorescent styrylpyridine dyes. 相似文献
40.
The phosphonate analogue of α-N-benzoyl protected phenylalanine methylester has been prepared by catalytic synthesis. Commonly used Rh-complexes has been applied in asymmetric hydrogenation to check their usefulness in the standard reaction. 相似文献