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221.
A. Haugeneder M. Hilmer C. Kallinger M. Perner W. Spirkl U. Lemmer J. Feldmann U. Scherf 《Applied physics. B, Lasers and optics》1998,66(3):389-392
Received: 19 January 1998 相似文献
222.
He Huang Yanxiu Li Yu Tong En‐Ping Yao Maximilian W. Feil Alexander F. Richter Markus Dblinger Andrey L. Rogach Jochen Feldmann Lakshminarayana Polavarapu 《Angewandte Chemie (International ed. in English)》2019,58(46):16558-16562
The growing demand for perovskite nanocrystals (NCs) for various applications has stimulated the development of facile synthetic methods. Perovskite NCs have often been synthesized by either ligand‐assisted reprecipitation (LARP) at room temperature or by hot‐injection at high temperatures and inert atmosphere. However, the use of polar solvents in LARP affects their stability. Herein, we report on the spontaneous crystallization of perovskite NCs in nonpolar organic media at ambient conditions by simple mixing of precursor–ligand complexes without application of any external stimuli. The shape of the NCs can be controlled from nanocubes to nanoplatelets by varying the ratio of monovalent (e.g. formamidinium+ (FA+) and Cs+) to divalent (Pb2+) cation–ligand complexes. The precursor–ligand complexes are stable for months, and thus perovskite NCs can be readily prepared prior to use. Moreover, we show that this versatile synthetic process is scalable and generally applicable for perovskite NCs of different compositions. 相似文献
223.
Application of a hexapole collision and reaction cell in ICP-MS Part II: Analytical figures of merit and first applications 总被引:1,自引:0,他引:1
I. Feldmann N. Jakubowski C. Thomas D. Stuewer 《Fresenius' Journal of Analytical Chemistry》1999,365(5):422-428
The application of an ion-guiding gas-filled hexapole collision/reaction cell in ICP-MS has been studied to characterize
the analytical figures of merit that can be achieved with this approach. For the elements investigated, application of a buffer
and a reaction gas resulted in improved sensitivities which are lowest for Be with about 7 · 107 cps per μg mL–1 and highest for Ba with about ?6 · 108 cps per μg mL–1. Relative standard deviations (RSD) < 0.1% were obtained. Application of the reaction gas H2 was used to suppress polyatomic ions caused by argon. The reduction amounted up to four orders of magnitude so that elements
such as Ca, K, Cr, Fe, As and Se could be analyzed in nitric and hydrochloric acid or in methanol. Detection limits of 6 pg
mL–1 for Cr in 2% methanol, 23 pg mL–1 for As and 9 pg mL–1 for Se in 0.28 M HCl were achieved. For other elements detection limits ?< 1 pg mL–1 were realized in the medium and high mass range. Accuracy was proved using the NIST 1643d standard reference material.
Received: 10 May 1999 / Revised: 4 June 1999 / Accepted: 12 June 1999 相似文献
224.
Siethoff C Feldmann I Jakubowski N Linscheid M 《Journal of mass spectrometry : JMS》1999,34(4):421-426
The quantitative determination of nucleotides from DNA modified by styrene oxide is described using a combination of inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) and electrospray ionization mass spectrometry (ESI-MS), both interfaced to reversed-phase high-performance liquid chromatography (HPLC). LC/ICP-MS (resolution > 1500 to discriminate against 15N16O+ and 14N16OH+) was employed to determine quantitatively the content of modified nucleotides in standard solutions based on the signal of phosphorus; phosphoric acid served as an internal standard. By means of the standard addition technique the sensitivity of the LC/ESI-MS approach was subsequently determined. Since a comparison of UV, ICP and ESI-MS data suggested that in ESI-MS the ionization efficiency of the adducts is identical within the error limits, quantitative determination of all adducts is possible. For LC/ESI-MS with single ion monitoring, the detection limit for styrene oxide adducts of nucleotides was determined to be 20 pg absolute or 14 modified in 10(8) unmodified nucleotides in a 5 micrograms DNA sample, which comes close to the best methods available for the detection of chemical modifications in DNA. 相似文献
225.
S Wolf F Winter R Pöttgen N Middendorf W Klopper C Feldmann 《Dalton transactions (Cambridge, England : 2003)》2012,41(35):10605-10611
By reacting Fe(CO)(5) and SnI(4) in the ionic liquids [XIm][NTf(2)] (XIm: 1-ethyl-3-methylimidazolium/EMIm, 1-ethyl-imidazolium/EHIm, 1-propyl-3-methylimidazolium/PMIm; NTf(2): bistrifluoridomethansulfonimide), the compounds [XIm][FeI(CO)(3)(SnI(3))(2)] are obtained as transparent, dark red crystals. According to single-crystal structure analysis, the title compounds crystallize monoclinically and contain the anionic carbonyl complex [FeI(CO)(3)(SnI(3))(2)](-) as well as [EMIm](+), [EHIm](+) or [PMIm](+) cations. The anionic carbonyl is composed of a Sn-Fe-Sn barbell-shaped building unit with Fe-Sn distances of 252.0(1) pm. Herein, tin is coordinated distorted tetrahedrally by iodine; iron is coordinated pseudo-octahedrally by three carbonyl ligands, one iodine atom and two tin atoms. Bonding situation and valence state are investigated in detail for [EMIm][FeI(CO)(3)(SnI(3))(2)] based on bond-lengths considerations, infrared spectroscopy, M?ssbauer spectroscopy, density functional theory and DFT-based Mulliken population analysis. Hence, the formal oxidation state of the metal atoms can be concluded to Fe(±0) and Sn(3+). 相似文献
226.
Michel Feldmann 《Foundations of Physics Letters》1995,8(1):41-53
Using the new concept of "stochastic gauge system", we describe a novel loophole to circumvent the Einstein-Podolsky-Rosen (EPR) paradox. We derive a "realistic" (i.e., classical) model, free from any paradox, which exactly emulates the spin EPR experiment. We conclude that Bell's inequalities are violated in classical physics as well, or, conversely that quantum mechanical theory is logically consistent with relativity. 相似文献
227.
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229.
The influence of the pulsation of a plasma torch over the lateral intensity of the radiation and the radial temperature profile was studied. For the case of pulsation of the axis of a torch following a Gaussian distribution the exact integral equation was obtained relating the lateral intensity with and without pulsation. For a particular case the lateral distributions of radiation intensity were calculated for three different values of the Gaussian standard deviation. For the spectral line ArI 435.8 nm the radial temperature distributions with and without pulsations were calculated. The results show how pulsations can affect experimental results. 相似文献
230.
P. Feldmann 《Fresenius' Journal of Analytical Chemistry》1906,45(3-4):258
Ohne Zusammenfassung 相似文献