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The 3,4-dimethoxybenzyl group as solubilizing protective group for the in situ deprotection/deposition of extended aromatic thiolate monolayers

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Nano research 2023年第1期16卷 1695-1702页

作者： Adrian Wiesner Sonja Katzbach Dariusz Bebej Martina Dettenhöfer Michael Zharnikov Andreas Terfort institut für Anorganische und Analytische chemie Johann Wolfgang Goethe Universität FrankfurtMax-von-Laue-Straße 7Frankfurt am Main D-60438Germany Angewandte physikalische chemie Universität HeidelbergIm Neuenheimer Feld 253Heidelberg D-69120Germany

While self-assembled monolayers(SAMs)of aromatic thiolates are frequently used in a wide range of applications,their formation is often hampered by the low solubilities of their *** we introduce the 3,4-dimethoxybenzyl group as a protective group for the thiol moiety,which increases the solubility and stability of the precursor,but becomes cleaved off during monolayer formation,especially at elevated temperature(60°C)and in presence of protons(trifluoroacetic acid).for a series of substituted terphenylthiols as model systems,it could be demonstrated by using ellipsometry,infrared-reflection absorption spectroscopy,and scanning-tunneling microscopy that the resulting SAMs have the same structure and quality as the ones obtained from the respective unprotected *** protective group has the additional advantage to be stable under Pdcatalyzed C–C bond formation reaction conditions,facilitating the syntheses of the respective precursors.

关键词： self-assembled monolayers protective group solubility scanning-tunneling microscopy infrared-reflection absorption spectroscopy

Aromatic self-assembled monolayers with pentafluoro-λ^(6)-sulfanyl(−Sf_(5))termination:Molecular organization and charge transport properties

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Nano research 2023年第5期16卷 7991-8002页

作者： Yangbiao Liu Marc Zeplichal Sonja Katzbach Adrian Wiesner Saunak Das reas Terfort Michael Zharnikov Angewandte physikalische chemie Universität HeidelbergIm Neuenheimer Feld 253D-69120 HeidelbergGermany institut für Anorganische und Analytische chemie Johann Wolfgang Goethe Universität FrankfurtMax-von-Laue-Straße 7D-60438 Frankfurt am MainGermany

A series of molecules with oligophenylene backbone,thiolate anchoring group,pentafluoro-λ^(6)-sulfanyl(−Sf_(5))tail group was synthesized and used as precursors to form self-assembled monolayers(SAMs)on Au(111)*** resulting SAMs feature dense molecular packing,upright molecular orientation,chemically homogeneous SAM-ambient interface,comprised entirely of the−Sf_(5)*** SAMs exhibit exceptional wetting and electrostatic properties,showing advancing water contact angles up to 103°and work function values up to 5.96 eV—probably the highest values reported for any aromatic monolayers on *** also feature a comparably low value of the tunnelling decay coefficient(0.38±0.07Å^(−1)),typical of oligophenylene backbone,which is not affected by the introduction of the−Sf_(5)*** latter also hardly affects the current densities at a specific bias compared to analogous monolayers with other electronegative tail *** superior electrostatic and good charge transport properties of the designed,Sf_(5)-terminated SAMs make them potentially useful for interface engineering in organic electronics and photovoltaics.

关键词： backbone charge electrostatic

Molecular structure of diatomic lanthanide compounds

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Science China Chemistry 2002年第1期45卷 91-96页

作者：曹晓燕刘文剑 MichaelDolg institut für physikalische & theoretische chemie Bonn Germany Biochemistry Department Zhongshan University Guangzhou China Lehrstuhl für theoretische chemie Ruhr-Universität Bochum Germany

The molecular constants of selected diatomic lanthanide compounds (LaH, LaO, Laf, EuH, EuO, Euf, EuS, GdO, Gdf, GdH, YbH, YbO, Ybf, YbS, LuH, LuO and Luf) have been calculated by using relativistic small-core pseudopotentials and optimized (14s13p10d8f6g)/ [6s6p5d4f3g] valence basis sets. The results are in good agreement with available experimental data, with exception of YbO and Luf. The reasons for the discrepancies in case of YbO are due to a complicated mixing of configurations in the ground state, whereas in case of Luf the binding energy estimated by experimentalists appears to be too low.

关键词： molecular structure lanthanide element pseudopotential valence basis set.

High-Tc superconductor fe(Se,Te) monolayer:an intrinsic,scalable and electrically tunable Majorana platform

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National Science review 2022年第3期9卷 11-18页

作者： Xianxin Wu Xin Liu ronny Thomale Chao-Xing Liu institut für theoretische Physik und Astrophysik Julius-Maximilians-Universit?t Würzburg School of Physics Huazhong University of Science and Technology Wuhan National High Magnetic field Center Huazhong University of Science and Technology Department of Physics the Pennsylvania State University

Iron-based superconductors have been identified as a novel platform for realizing Majorana zero modes(MZMs) without heterostructures, due to their intrinsic topological properties and high-Tc superconductivity. In the two-dimensional limit, the feTe1-xSexmonolayer, a topological band inversion has recently been experimentally observed. Here, we propose to create MZMs by applying an in-plane magnetic field to the feTe1-xSexmonolayer and tuning the local chemical potential via electric *** to the anisotropic magnetic couplings on edges, an in-plane magnetic field drives the system into an intrinsic high-order topological superconductor phase with Majorana corner modes. furthermore, MZMs can occur at the domain wall of chemical potentials at either one edge or certain type of tri-junction in the two-dimensional bulk. Our study not only reveals the feTe1-xSexmonolayer as a promising Majorana platform with scalability and electrical tunability and within reach of contemporary experimental capability,but also provides a general principle to search for realistic realization of high-order topological superconductivity.

关键词： high-order topological superconductivity Majorana zero modes iron-based superconductors

Boron-modified perhydropolysilazane towards facile synthesis of amorphous SiBN ceramic with excellent thermal stability

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Journal of Advanced Ceramics 2022年第7期11卷 1104-1116页

作者： Ying ZHAN Wei LI Tianshu JIANG Claudia fASEL Emmanuel III rICOHErMOSO Jan BErNAUEr Zhaoju YU Zhenghao WU florian MÜLLEr-PLATHE Leopoldo MOLINA-LUNA ralf GrOTTENMÜLLEr ralf rIEDEL Department of Materials and Earth Sciences Technical University of DarmstadtD-64287 DarmstadtGermany College of Materials Key Laboratory of High Performance Ceramic Fibers(Xiamen University)Ministry of EducationXiamen 361005China Eduard-Zintl-institut für Anorganische und physikalische chemie Technical University of DarmstadtD-64287 DarmstadtGermany Merck KGaA Performance MaterialsD-64293DarmstadtGermany

SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric *** work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic ***-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis *** obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon ***,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.

关键词： polymer-derived ceramics(PDCs) SiBN crystallization molecular dynamics oxidation resistanc

Selective Suspension in Aqueous Sodium Dodecyl Sulfate According to Electronic Structure Type Allows Simple Separation of Metallic from Semiconducting Single-Walled Carbon Nanotubes

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Nano research 2009年第8期2卷 599-606页

作者： Kai Moshammer frank Hennrich Manfred M.Kappes forschungszentrum Karlsruhe Institut für NanotechnologieD-76021 KarlsruheGermany institut für physikalische chemie Universität KarlsruheD-76128 KarlsruheGermany

Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNTs)when using aqueous sodium dodecyl sulphate(SDS)*** show here that both methods rely on an initial dispersion-by-sonication step,which is already selective with respect to electronic structure *** corresponding aqueous SDS“starting”suspensions obtained after sonication and purifi cation by simple centrifugation(70,000 g,1 h)contain semiconducting SWNTs primarily in the form of small bundles whereas metallic SWNTs are predominantly suspended as individual *** gradient centrifugation then separates the bundles from the individual tubes on the basis of differences in their overall buoyant *** electrophoresis separates the longer bundles from the shorter individual tubes on the basis of their different *** also demonstrate that such starting suspensions can be fractionated according to electronic structure type by even simpler techniques such as size exclusion chromatography or gel fi ltration,thus opening the way for simple scale-up.

关键词： Single-walled carbon nanotubes metallic–semiconducting separation electrophoresis density gradient centrifugation size exclusion chromatography

High-dimensional neural network potentials for magnetic systems using spin-dependent atom-centered symmetry functions

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npj Computational Materials 2021年第1期7卷 1541-1551页

作者： Marco Eckhoff Jörg Behler Universität Göttingen Institut für Physikalische ChemieTheoretische ChemieTammannstrasse 637077 GöttingenGermany Universität Göttingen International Center for Advanced Studies of Energy Conversion(ICASEC)Tammannstrasse 637077 GöttingenGermany

Machine learning potentials have emerged as a powerful tool to extend the time and length scales of first-principles quality ***,most machine learning potentials cannot distinguish different electronic spin arrangements and thus are not applicable to materials in different magnetic *** we propose spin-dependent atom-centered symmetry functions as a type of descriptor taking the atomic spin degrees of freedom into *** used as an input for a high-dimensional neural network potential(HDNNP),accurate potential energy surfaces of multicomponent systems can be constructed,describing multiple collinear magnetic *** demonstrate the performance of these magnetic HDNNPs for the case of manganese oxide,*** method predicts the magnetically distorted rhombohedral structure in excellent agreement with density functional theory and *** efficiency allows to determine the Néel temperature considering structural fluctuations,entropic effects,and *** method is general and is expected to be useful also for other types of systems such as oligonuclear transition metal complexes.

关键词： magnetic symmetry neural

Millimeter gap contrast as a probe for turbulence level in protoplanetary disks

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 131-144页

作者： Yao Liu Gesa H.-M.Bertrang Mario flock Giovanni P.rosotti Ewine f.van Dishoeck Yann Boehler Stefano facchini Can Cui Sebastian Wolf Min fang Max-Planck-institut für Extraterrestrische Physik Garching85748Germany Purple Mountain Observatory&Key Laboratory for radio Astronomy Chinese Academy of SciencesNanjing210023China Max-Planck-institut für Astronomie HeidelbergD-69117Germany Leiden Observatory Leiden UniversityLeidenNL-2300the Netherlands School of Physics and Astronomy University of LeicesterLeicesterLE17RHUK UniversitéGrenoble Alpes French National Centre for Scientific ResearchInstitute for Planetary Sciences and AstrophysicsGrenobleGrenobleF-38000France European Southern Observatory Garching85748Germany Department of Applied Mathematics and Theoretical Physics University of CambridgeCentre for Mathematical SciencesCambridgeCB3 OWAUK institut für theoretische Physik und Astrophysik Christian-Albrechts-Universität zu kielKiel24118Germany

Turbulent motions are believed to regulate angular momentum transport and influence dust evolution in protoplanetary *** the strength of turbulence is challenging through gas line observations because of the requirement for high spatial and spectral resolution data,and an exquisite determination of the *** this work,taking the well-known HD 163296 disk as an example,we investigated the contrast of gaps identified in high angular resolution continuum images as a probe for the level of *** self-consistent radiative transfer models,we simultaneously analyzed the radial brightness profiles along the disk major and minor axes,and the azimuthal brightness profiles of the B67 and B100 *** fitting all the gap contrasts measured from these profiles,we constrained the gas-to-dust scale height ratioΛto be 3.0^(+0.3)_(−0.8),1.2^(+0.1)_(−0.1),and≥6.5 for the D48,B67,and B100 regions,*** varying gas-to-dust scale height ratios indicate that the degree of dust settling changes with *** inferred values forΛtranslate into a turbulence level of α_(turb)regions,which is consistent with previous upper limits set by gas line ***,turbulent motions in the B67 ring are strong with α_(turb)∼1.2×10^(−2).Due to the degeneracy betweenΛand the depth of dust surface density drops,the turbulence strength in the D86 gap region is not constrained.

关键词： protoplanetary disks radiative transfer planet formation

t-Private and t-Secure Auctions

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Journal of Computer Science & Technology 2008年第5期23卷 694-710页

作者： Markus Hinkelmann Andreas Jakoby Peer Stechert institut für theoretische Informatik Universitt zu Lübeck Germany fachgruppe Didaktik der Informatik und E-Learning Universitt Siegen Germany

In most of the auction systems the values of bids are known to the auctioneer. This allows him to manipulate the outcome of the auction. Hence, one might be interested in hiding these values. Some cryptographically secure protocols for electronic auctions have been presented in the last decade. Our work extends these protocols in several ways. On the basis of garbled circuits, i.e., encrypted circuits, we present protocols for sealed-bid auctions that fulfill the following requirements： 1） protocols are information-theoretically t-private for honest but curious parties; 2） the number of bits that can be learned by malicious adversaries is bounded by the output length of the auction; 3） the computational requirements for participating parties are very low： only random bit choices and bitwise computation of the XOr-function are necessary. Note that one can distinguish between the protocol that generates a garbled circuit for an auction and the protocol to evaluate the auction. In this paper we address both problems. We will present a t-private protocol for the construction of a garbled circuit that reaches the lower bound of 2t ＋ 1 parties, and finally, we address the problem of bid changes in an auction. a more randomness efficient protocol for （t ＋ 1）^2 parties

关键词： multi-party private and secure computation garbled circuits private auctions