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71.
Richard C. Brewster Geňa Hahn Stacey Wynn Lamont Chester Lipka 《Discrete Mathematics》2012,312(10):1638-1645
The reconstruction number of a graph is the smallest number of vertex-deleted subgraphs needed to uniquely determine the graph up to isomorphism. Bollobás showed that almost all graphs have reconstruction number equal to three. McMullen and Radziszowski published a catalogue of all graphs on at most ten vertices with reconstruction number greater than three. We introduce constructions that generalize the examples identified in their work. In particular, we use lexicographic products of vertex transitive graphs with certain starter graphs from the work of Myrvold and from the work of Harary and Plantholt to generate new infinite families of graphs with high reconstruction numbers. In the process, we settle a question of McMullen and Radziszowski. 相似文献
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74.
F. E. Hahn D. Le Van L. Wittenbecher M. C. Moyes T. Von Fehren R. Fröhlich 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1863-1867
The stable singlet carbenes N,N '-bis(2,2-dimethylpropyl)-benzimidazolin-2-ylidene 1 and 1,3,4,5-tetramethylimidazol-2-ylidene 2 react with phosphaalkynes P L C-- t Bu ( 3a ) or P L C--N i Pr 2 ( 3b ) regioselective to give the aromatic 1,2,4-triphosphole derivatives ( 1 or 2 + 3a M 6a or 6b , respectively) or 1,2,3-triphosphetene ( 1 + 3b M 7 ) or azaphospholene ( 2 + 3b M 9 ) in almost quantitative yields. The mechanisms of the surprising formation of compound 9 under C--H-activation was studied by quantum chemical DFT calculations. 相似文献
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76.
Constanze Keck Dr. Jennifer Hahn Divanshu Gupta Prof. Dr. Holger F. Bettinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(5):e202103614
The boron-nitrogen analogue of ortho-benzyne, 1,2-azaborinine, is a reactive intermediate that features a formal boron-nitrogen triple bond. We here show by combining experimental and computational techniques that the Lewis acidity of the boron center of dibenzo[c,e][1,2]azaborinine allows interaction with the silicon containing single bonds Si−E through the silicon bonding partner E (E=F, Cl, OR, H). The binding to boron activates the Si−E bonds for subsequent insertion reaction. This shows that the BN-aryne is a ferocious species that even can activate and insert into the very strong Si−F bond. 相似文献
77.
Investigation of fill factor losses on 20.2% efficient n‐type mono‐like silicon solar cells with laser contact opening 下载免费PDF全文
Alexander Frey Josh Engelhardt Gabriel Micard Giso Hahn Barbara Terheiden 《固体物理学:研究快报》2016,10(2):143-147
Large area (243.36 cm2) back‐junction passivated emitter, rear totally diffused (PERT) solar cells with laser contact opening (LCO) on n‐type mono‐like crystalline Si with efficiencies of 20.2% are presented. Boron emitters with high electrical quality (implied open circuit voltage iVOC up to 700 mV) are formed during a co‐diffusion step using SiOx:B layers. Increasing the rear metal contact coverage, we observed a decrease in fill factor (FF) instead of the expected increase due to the decrease of the back side series resistance. We show that it can be attributed to recombination centers (RCs) in the space charge region underneath the contact spots inducing an increasing second diode contribution. The presented empirical model for the RCs implemented in Synopsys Sentaurus TCAD allows for a successful reproduction of the FF, pseudo FF and VOC behaviour with contact coverage. According to this model, the RCs induced by laser ablation and subsequently evaporation of Al have a shallow exponential distribution with a characteristic length of LT = 0.2 µm and an effective surface density of N *T0 = 25 cm–1. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
78.
Lucas Ueberricke Dr. Bahiru Punja Benke Tobias Kirschbaum Dr. Sebastian Hahn Dr. Frank Rominger Prof. Dr. Uwe H. F. Bunz Prof. Dr. Michael Mastalerz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2043-2049
A six-step synthesis towards a tribenzotriquinacene (TBTQ) bearing three quinoxalinophenanthrophenazine (QPP) units is presented. The optoelectronic properties are investigated and the effect of the three-dimensional arrangement of the individual QPP planes is examined using optical spectroscopy, electrochemical analysis and quantum-chemical calculations. 相似文献
79.
Influence of higher harmonics of the undulator in X‐ray polarimetry and crystal monochromator design 下载免费PDF全文
Berit Marx‐Glowna Kai S. Schulze Ingo Uschmann Tino Kämpfer Günter Weber Christoph Hahn Hans‐Christian Wille Kai Schlage Ralf Röhlsberger Eckhart Förster Thomas Stöhlker Gerhard G. Paulus 《Journal of synchrotron radiation》2015,22(5):1151-1154
The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel‐cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs. 相似文献
80.
Yang Li Yuan‐Yuan An Jian‐Zhong Fan Xiao‐Xu Liu Xin Li F. Ekkehardt Hahn Yao‐Yu Wang Ying‐Feng Han 《Angewandte Chemie (International ed. in English)》2020,59(25):10073-10080
A series of supramolecular assemblies of types [Ag8( L )4](PF6)8 and [Ag4( L )2](PF6)4, obtained from the tetraphenylethylene (TPE) bridged tetrakis(1,2,4‐triazolium) salts H4‐L(PF6)4 and AgI ions, is described. The assembly type obtained dependends on the N‐wingtip substituents of H4‐L(PF6)4. Changes in the lengths of the N4‐wingtip substituents enables controlled formation of assemblies with either [Ag4( L )2](PF6)4 or [Ag8( L )4](PF6)8 stoichiometry. The molecular structures of selected [Ag8( L )4](PF6)8 and [Ag4( L )2](PF6)4 assemblies were determined by X‐ray diffraction analyses. While H4‐ L (PF6)4 does not exhibit fluorescence in solution, their tetra‐NHC (NHC=N‐heterocyclic carbene) assemblies do upon NHC–metal coordination. Upon irradiation, all assemblies undergo a light‐induced, supramolecule‐to‐supramolecule structural transformation by an oxidative photocyclization involving phenyl groups of the TPE core, resulting in a significant change of the luminescence properties. 相似文献