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991.
In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology acco... 相似文献
992.
The Ramanujan Journal - In Maier and Tenenbaum (Invent Math 76(1):121–128, 1984), Tenenbaum and the first author proved an old conjecture of Paul Erd?s about the propinquity of divisors... 相似文献
993.
994.
Dr. Matthias Müller M. Sc. Steffen Maier Olena Tverskoy Dr. Frank Rominger Dr. Jan Freudenberg Prof. Uwe H. F. Bunz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(5):1982-1985
In combination with bulky substituents at the core, fourfold benzannulation at the cata-positions stabilizes a nonacene sufficiently to allow its isolation and characterization by 1H NMR and X-ray analysis. The four benzo units blueshift the absorption spectrum in comparison to a solely linear nonacene, but significantly increase the stability in the solid state. 相似文献
995.
Tobias Stohr Dr. Joachim Brötz Prof. Dr. Mehtap Oezaslan Dr. Falk Muench 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(14):3030-3033
Autocatalytic deposition represents a facile, versatile, and scalable wet-chemical tool for nanofabrication. However, the intricate component interplay in plating baths containing multiple metal species impedes alloy deposition. We resolved this challenge in the bimetallic copper-platinum system by exploiting the kinetic stability of platinum complexes, which allows adjusting their ligand sphere and thus reactivity independently from the present copper ions in a preceding, thermally activated ligand exchange step. By using metastable PtIV precursors of varying degrees of complexation, copper-platinum alloys of adjustable atomic ratio were plated from solutions of identical composition and concentration, but differing local coordination environment. Due to its excellent conformity and nanoscale homogeneity, the reaction is compatible with ambitious 3D substrate morphologies, as demonstrated in the template-assisted fabrication of nanotubes with high aspect ratio. The ability to generate additional synthetic degrees of freedom by decoupling the metal complex speciation from the solution composition is of large interest for redox-chemical synthesis techniques, such as electrodeposition or nanoparticle colloid production. 相似文献
996.
Bettina S. J. Heller Matthias Lexow Francesco Greco Dr. Sunghwan Shin Dr. Gabriel Partl Dr. Florian Maier Prof. Dr. Hans-Peter Steinrück 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(5):1117-1126
Using angle-resolved X-ray photoelectron spectroscopy (ARXPS), we investigate the topmost nanometers of various binary ionic liquid (IL) mixtures at different temperatures in the liquid state. The mixtures consist of ILs with the same [PF6]− anion but two different cations, namely 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF6], and 1-butyl-3-methylimidazolium hexafluorophosphate, [C4C1Im][PF6], with 10, 25, 50 and 75 mol % content of [PFBMIm][PF6]. We observe a preferential enrichment of the fluorinated chain in the topmost layer, relative to the bulk composition, which is most pronounced for the lowest content of [PFBMIm][PF6]. Upon cooling the mixtures stepwise from 95 °C until surface charging effects in XPS indicate solidification, we observe a pronounced increase in surface enrichment of the fluorinated chain with decreasing temperature in the liquid state. In contrast to the mixtures with lower [PFBMIm][PF6] contents, cooling the 75 mol % mixture additionally shows an abrupt decrease of the fluorinated chain signal before complete solidification occurs, which is assigned to partial precipitation effects. 相似文献
997.
Kapil Shyam Lokare Beatrice Braun‐Cula Christian Limberg Marcel Jorewitz John T. Kelly Knut R. Asmis Stephen Leach Carsten Baldauf Itziar Goikoetxea Joachim Sauer 《Angewandte Chemie (International ed. in English)》2019,58(3):902-906
Even though aluminas and aluminosilicates have found widespread application, a consistent molecular understanding of their surface heterogeneity and the behavior of defects resulting from hydroxylation/dehydroxylation remains unclear. Here, we study the well‐defined molecular model compound, [Al3(μ2‐OH)3(THF)3(PhSi(OSiPh2O)3)2], 1 , to gain insight into the acid–base reactivity of cyclic trinuclear Al3(μ2‐OH)3 moieties at the atomic level. We find that, like zeolites, they are sufficiently acidic to catalyze the isomerization of olefins. DFT and gas phase vibrational spectroscopy on solvent‐free and deprotonated 1 show that the six‐membered ring structure of its Al3(μ2‐OH)3 core is unstable with respect to deprotonation of one of its hydroxy groups and rearranges into two edge‐sharing four‐membered rings. This renders AlIV?O(H)?AlIV units strong acid sites, and all results together suggest that their acidity is similar to that of zeolitic SiIV?O(H)?AlIV groups. 相似文献
998.
999.
1000.
Summary Future generations of electronic components need new methods for thickness measurement. This paper demonstrates that electron spectroscopy is exact enough to measure thicknesses up to 15 nm with an accuracy better than 5%. The model of a constant mean free path of the electrons only varying with the material has to be modified. One has to observe the complete set of all parameters for such thickness measurements.
Schichtdicken-Messung dünner Dielektrica mit Hilfe der Electronenspektroskopie相似文献