Publications at the Department of Mathematics and Natural Sciences from 2019

Results: 463
Created on: Fri, 17 Sep 2021 23:17:46 +0200 in 0.0922 sec

Emminger, Carola; Abadizaman, Farzin; Samarasingha, Nuwanjula S.; Menéndez, José; Espinoza, Shirly; Richter, Steffen; Rebarz, Mateusz; Herrfurth, Oliver; Zahradník, Martin; Schmidt-Grund, Rüdiger; Andreasson, Jakob; Zollner, Stefan;
Analysis of temperature-dependent and time-resolved ellipsometry spectra of Ge. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), insges. 2 S.
Paszuk, Agnieszka; Nandy, Manali; Kleinschmidt, Peter; Hannappel, Thomas;
In situ monitoring of As-P exchange on Ge(100) surfaces in GaAs-rich CVD reactors for low-defect III-V multijunction solar cells. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), S. 339-341
Nandy, Manali; Paszuk, Agnieszka; Feifel, Markus; Koppka, Christian; Kleinschmidt, Peter; Dimroth, Frank; Hannappel, Thomas;
Reduction of defects in GaP layers grown on Si(100) by MOCVD. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2021), S. 1344-1347
Zhou, Xue-Quan; Mytiliniou, Maria; Hilgendorf, Jonathan; Zeng, Ye; Papadopoulou, Panagiota; Shao, Yang; Dominguez, Maximilian Paradiz; Zhang, Liyan; Hesselberth, Marcel B. S.; Bos, Erik; Siegler, Maxime A.; Buda, Francesco; Brouwer, Albert M.; Kros, Alexander; Koning, Roman I.; Heinrich, Doris; Bonnet, Sylvestre;
Intracellular dynamic assembly of deep-red emitting supramolecular nanostructures based on the Pt Pt metallophilic interaction. - In: Advanced materials. - Weinheim : Wiley-VCH, ISSN 1521-4095, Bd. 33 (2021), 37, S. 1-13
Mehler, Alexander; Néel, Nicolas; Voloshina, Elena; Dedkov, Yuriy; Kröger, Jörg;
Second floor of flatland: epitaxial growth of graphene on hexagonal boron nitride. - In: Small : nano micro.. - Weinheim : Wiley-VCH, ISSN 1613-6829, Bd. 17 (2021), 36, S. 1-9

In the studies presented here, the subsequent growth of graphene on hexagonal boron nitride (h-BN) is achieved by the thermal decomposition of molecular precursors and the catalytic assistance of metal substrates. The epitaxial growth of h-BN on Pt(111) is followed by the deposition of a temporary Pt film that acts as a catalyst for the fabrication of the graphene sheet. After intercalation of the intermediate Pt film underneath the boron-nitride mesh, graphene resides on top of h-BN. Scanning tunneling microscopy and density functional calculations reveal that the moiré pattern of the van-der-Waals-coupled double layer is due to the interface of h-BN and Pt(111). While on Pt(111) the graphene honeycomb unit cells uniformly appear as depressions using a clean metal tip for imaging, on h-BN they are arranged in a honeycomb lattice where six protruding unit cells enframe a topographically dark cell. This superstructure is most clearly observed at small probe-surface distances. Spatially resolved inelastic electron tunneling spectroscopy enables the detection of a previously predicted acoustic hybrid phonon of the stacked materials. Its' spectroscopic signature is visible in surface regions where the single graphene sheet on Pt(111) transitions into the top layer of the stacking.
Ilchmann, Achim; Kirchhoff, Jonas;
Differential-algebraic systems are generically controllable and stabilizable. - In: Mathematics of control, signals, and systems : MCSS.. - London : Springer, ISSN 1435-568X, Bd. 33 (2021), 3, S. 359-377

We investigate genericity of various controllability and stabilizability concepts of linear, time-invariant differential-algebraic systems. Based on well-known algebraic characterizations of these concepts (see the survey article by Berger and Reis (in: Ilchmann A, Reis T (eds) Surveys in differential-algebraic equations I, Differential-Algebraic Equations Forum, Springer, Berlin, pp 1-61., we use tools from algebraic geometry to characterize genericity of controllability and stabilizability in terms of matrix formats.
Zhang, Keyu; Cui, Dingfang; Huang, Xiaopeng; Liang, Feng; Gao, Geng; Song, Tingyu; Zhang, Libo; Yao, Yaochun; Lei, Yong;
Insights into the interfacial chemistry and conversion mechanism of iron oxalate toward the reduction by lithium. - In: The chemical engineering journal. - Amsterdam : Elsevier, ISSN 1873-3212, Bd. 426 (2021)

The origin of excellent lithium storage ability and high irreversible capacity is probably the least understood component for transition-metal oxalates as anode materials in lithium-ion batteries. Considerable efforts have been put into understanding their electrochemical reaction mechanisms, but these insights have mostly been unilateral and unsystematic. Herein, the interface characteristic between iron oxalate anode and electrolyte and detailed conversion process were investigated to explore the source of irreversible Li+ storage. In particular, a gelatinous "organic" layer identified oxygen, fluorine and phosphorus as the main chemical elements can be re-oxidized and exhibits an obviously reversible conversion between sedimentation and decomposition during its initial lithiation process, despite the general belief that it shows similar electrochemically inert to solid-electrolyte interphase (SEI). Meanwhile, this special interface layer leads to higher ability of Li+ ions diffusion and smaller charge-transfer resistance, which is the vital role for excellent rate capability. Furthermore, ex situ FTIR analysis confirms the formation and residue of new intermediate compound of Li2Fe(C2O4)2, thus making a part of initial irreversible capacity. It is also found that the iron oxalate electrode with larger capacitive contribution still has more widely application in energy storage of supercapacitors in future.
Zeußel, Lisa; Mai, Patrick; Sharma, Sanjay; Schober, Andreas; Ren, Shizhan; Singh, Sukhdeep;
Colorimetric method for instant detection of lysine and arginine using novel Meldrum's acid-furfural conjugate. - In: ChemistrySelect. - Weinheim : Wiley-VCH, ISSN 2365-6549, Bd. 6 (2021), 27, S. 6834-6840

In the past few years Meldrum's acid furfural conjugate (MAFC) have been extensively explored as starting material for the synthesis of photo switchable donor acceptor stenhouse adducts (DASA). Hereby, we have explored the interaction of MAFC with various amino acids. To our surprise, nitrogen rich amino acids like lysine and arginine interact spontaneously with MAFC to give colored adduct immediately, whereas other amino acids, including nitrogen rich histidine, didn't show any coloration. Naked eye detection of lysine in benign solvent make this reagent an attractive new entry to the collection of chemosensors for the colorimetric detection of lysine and arginine. Intense coloration corresponds to the absorption at 514 nm under UV-Vis spectrometer. Lowest concentration of 100 m can be detected with UV-Vis spectrometer. NMR titrations reveals that the appearance of color is due to ring opening of a furfural that leads to the formation of conjugated triene species. Compared to previously reported chemosensors for lysine and arginine, MAFC offers advantages including simple synthesis, easy handling, high speed, low cost, good sensitivity/selectivity.
Wu, Xiaocui; Wiame, Frédéric; Maurice, Vincent; Marcus, Philippe;
Molecular scale insights into interaction mechanisms between organic inhibitor film and copper. - In: npj Materials degradation. - [London] : Macmillan Publishers Limited, part of Springer Nature, ISSN 2397-2106, Bd. 5 (2021), S. 1-8

A model experimental approach, providing molecular scale insight into the build up mechanisms of a corrosion inhibiting interface, is reported. 2-mercaptobenzimidazole (2-MBI), a widely used organic inhibitor, was deposited from the vapor phase at ultra-low pressure on copper surfaces in chemically-controlled state, and X-ray photoelectron spectroscopy was used in situ to characterize the adsorption mechanisms upon formation of the inhibiting film. On copper surfaces prepared clean in the metallic state, the intact molecules lie flat at low exposure, with sulfur and both nitrogen atoms bonded to copper. A fraction of the molecules decomposes upon adsorption, leaving atomic sulfur on copper. At higher exposure, the molecules adsorb in a tilted position with sulfur and only one nitrogen bonded to copper, leading to a densification of 2-MBI in the monolayer. A bilayer is formed at saturation with the outer layer not bonded directly to copper. In the presence of a pre-adsorbed 2D oxide, oxygen is substituted and the molecules adsorb intactly without decomposition. A 3D oxide prevents the bonding of sulfur to copper. The molecular film formed on metallic and 2D oxide pre-covered surfaces partially desorbs and decomposes at temperature above 400 ˚C, leading to the adsorption of atomic sulfur on copper.
Wu, Xiaocui; Wiame, Frédéric; Maurice, Vincent; Marcus, Philippe;
Effects of water vapour on 2-mercaptobenzothiazole corrosion inhibitor films deposited on copper. - In: Corrosion science : the journal on environmental degradation of materials and its control ; an official journal of the Institute of Corrosion.. - Amsterdam [u.a.] : Elsevier Science, Bd. 189 (2021)

The effects of water on 2-mercaptobenzothiazole (2-MBT) film pre-formed on copper at low pressure and room temperature was investigated in situ by X-ray photoelectron spectroscopy. Upon exposure to water vapour at 5×10 6 mbar, the 2-MBT molecules not directly bonded to copper desorb, until only one monolayer remains adsorbed. Further exposure leads to cleavage of the bond between exocyclic sulphur and copper, whereas nitrogen remains bonded to copper. Dissociative adsorption of water is observed, without copper oxidation for exposure up to 3×106L. This work brings new molecular scale insight into corrosion inhibition mechanisms in water-containing environments.