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484 results on '"Heinke, Lars"'

156. Photoswitching in nanoporous, crystalline solids: an experimental and theoretical study for azobenzene linkers incorporated in MOFs

Author

Wang, Zhengbang, primary, Heinke, Lars, additional, Jelic, Jelena, additional, Cakici, Murat, additional, Dommaschk, Marcel, additional, Maurer, Reinhard J., additional, Oberhofer, Harald, additional, Grosjean, Sylvain, additional, Herges, Rainer, additional, Bräse, Stefan, additional, Reuter, Karsten, additional, and Wöll, Christof, additional

Published
2015
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163. Mass transfer in one-dimensional nanoporous crystals with different surface permeabilities

Author

Heinke, Lars, Kärger, Jörg, and Universität Leipzig

Subjects
diffusion, transport, Physics::Optics, ddc:530
Abstract

The use of optical techniques, such as interference microscopy and IR micro-imaging, has enabled the direct observation of transient concentration profiles. In a one-dimensional crystal, surface permeabilities on opposing crystal faces are usually equal, so that mass transfer occurs symmetrically and the fluxes through both crystal faces are identical. If the surface permeabilities on opposing crystal faces are different from each other, mass transfer is not symmetrical anymore. We are going to show that the fraction of molecular uptake (or release) through a given host face is inversely proportional to the time constant of uptake/release via this crystal face. This finding permits a straightforward estimate of the influence of asymmetry on overall uptake.

Published
2008

164. The options of interference microscopy to explore the significance of intracrystalline diffusion and surface permeation for overall mass transfer on nanoporous materials: The options of interference microscopy to explore the significance ofintracrystalline diffusion and surface permeation for overall masstransfer on nanoporous materials

Author

Heinke, Lars, Kortunov, Pavel, Tzoulaki, Despina, Kärger, Jörg, University of Leipzig, ExxonMobil Research and Engineering Company, and Universität Leipzig

Subjects
diffusion, transport, ddc:530
Published
2007

165. Application of Boltzmann’s integration method under non-ideal conditions

Author

Heinke, Lars and Universität Leipzig

Subjects
diffusion, transport, ddc:530
Abstract

Boltzmann’s integration method may prove to be a very powerful tool to study the transport diffusion of guest molecules in nanoporous host systems. In many cases, however, the prerequisites for applying this method are not completely fulfilled. In the following, the consequences of these deviations on the accuracy of the obtained results are discussed. It is found that the results of Boltzmann’s integration method can be corrected by different considerations. The discussion is focussed on the concentration profiles observed during the adsorption and desorption of methanol in ferrierite-type crystals as observable by interference microscopy.

Published
2007

166. Significance of concentration-dependent intracrystalline diffusion and surface permeation for overall mass transfer

Author

Heinke, Lars and Universität Leipzig

Subjects
diffusion, transport, ddc:530
Abstract

The intracrystalline concentration profiles evolving during molecular uptake and release by nanoporous materials as accessible by interference microscopy contain a lot of hidden information. For concentration-independent transport parameter, the influence of surface resistances to overall mass transfer can be calculated by correlating the actual surface concentration with the overall uptake. By using a numerical solution of Fick’s 2nd law and considering a large variety of concentration dependencies of the transport diffusivity and the surface permeability, we show that the factor by which the transport process is retarded by the surface resistance may reasonably well be estimated by the type of correlation between the actual boundary concentration and the total uptake at a given time. In this way, a novel technique of uptake analysis which may analytically be shown to hold for constant diffusivities and surface permeabilities, is shown to be quite generally applicable.

Published
2007

168. Innenrücktitelbild: Chirales Porphyrin durch Einbau in metallorganisches Gerüst erlaubt fotoleitende Filme für die Detektion von zirkular polarisiertem Licht (Angew. Chem. 10/2023).

Author

Li, Chun, Schopmans, Henrik, Langer, Lukas, Marschner, Stefan, Chandresh, Abhinav, Bürck, Jochen, Tsuchiya, Youichi, Chihaya, Adachi, Wenzel, Wolfgang, Bräse, Stefan, Kozlowska, Mariana, and Heinke, Lars

Subjects
METAL-organic frameworks, PORPHYRINS, BINAPHTHOL, MOLECULES, METALLOPORPHYRINS
Abstract

While the porphyrin molecules in solution (red) are planar, as common porphyrin, the porphyrin cores are twisted and chiral upon assembly in the metal-organic framework. Keywords: BINOL; Chirales Porphyrin; Fotodetektoren; Metallorganische Gerüste; Zirkular Polarisiertes Licht DE BINOL Chirales Porphyrin Fotodetektoren Metallorganische Gerüste Zirkular Polarisiertes Licht 1 1 1 02/22/23 20230301 NES 230301 B A chiral metal-organic framework film b with optoelectronic properties based on functionalized porphyrin molecules is presented by Mariana Kozlowska, Lars Heinke et al. in their Research Article (e202217377). The close packing and the crystalline order of the porphyrin cores in the film result in excellent photoconduction properties and sensitivity to circularly polarized light. [Extracted from the article]

Published
2023
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170. Interaction of Human Plasma Proteins with Thin Gelatin-Based Hydrogel Films: A QCM-D and ToF-SIMS Study

Author

Schönwälder, Sina M. S., primary, Bally, Florence, additional, Heinke, Lars, additional, Azucena, Carlos, additional, Bulut, Özgül D., additional, Heißler, Stefan, additional, Kirschhöfer, Frank, additional, Gebauer, Tim P., additional, Neffe, Axel T., additional, Lendlein, Andreas, additional, Brenner-Weiß, Gerald, additional, Lahann, Jörg, additional, Welle, Alexander, additional, Overhage, Jörg, additional, and Wöll, Christof, additional

Published
2014
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172. Platinum nanoprisms :Imaging and interaction with CO studied by HP-STM

Author

Scientific Meeting of the Wallonia Network for Nanotechnology (10: 2013-04-18: Namur, Belgique), Barroo, Cédric, Heinke, Lars, Zhu, Zhongwei, Visart de Bocarmé, Thierry, Kruse, Norbert, Somorjai, Gabor A., Scientific Meeting of the Wallonia Network for Nanotechnology (10: 2013-04-18: Namur, Belgique), Barroo, Cédric, Heinke, Lars, Zhu, Zhongwei, Visart de Bocarmé, Thierry, Kruse, Norbert, and Somorjai, Gabor A.

Abstract

The Catalysts with high activity and selectivity are widely used, and platinum is one of the most metal used in heterogeneous catalysis. During the reaction, the catalysts undergo changes of their structure and of their chemical composition prior their steady state activity. As often stated, the reactants forms their own catalyst. Those changes occurs at real working pressure and temperature and are not majority of the industrial production is based on the application of a catalytic process. always easily accessible to UHV-based techniques. The high-pressure STM allows to study those changes under more realistic conditions (up to 1000 Torr of well-controlled gaseous environment). Studies on stepped Pt crystal surface highlights the breaking of the steps into 2 nm clusters [1]. The study of more realistic catalysts consists in Pt-based nanoparticles. The e-beam physical vapor deposition (eBPVD) is an efficient way to synthesize regular Pt-patterns (nanoprisms) with good reproducibility, info:eu-repo/semantics/nonPublished

Published
2013

173. Pt-based nanoparticles: Synthesis and imaging by high pressure-STM

Author

Interdisciplinary Surface Science Conference (19: 2013-03-26: Nottingham, UK), Barroo, Cédric, Heinke, Lars, Zhu, Zhongwei, Visart de Bocarmé, Thierry, Kruse, Norbert, Somorjai, Gabor A., Interdisciplinary Surface Science Conference (19: 2013-03-26: Nottingham, UK), Barroo, Cédric, Heinke, Lars, Zhu, Zhongwei, Visart de Bocarmé, Thierry, Kruse, Norbert, and Somorjai, Gabor A.

Abstract

HP-STM is an efficient method to study structural changes of the catalyst under different gas mixtures. The particles have to be homogeneously distributed over the region of analysis. Colloidal synthesis is a reliable way to produce monodisperse NP’s with narrow size distribution, but the disadvantages of this synthesis are:• the capping agent has to be removed without damaging the substrate by avoiding aggregation of the nanoparticles• the deposition process (dip coating or Langmuir-Blodgett deposition) induces unavoidable dirt on surfaceWe were able to image PtCo nanoparticles with good resolution., info:eu-repo/semantics/nonPublished

Published
2013

174. Frontispiz: Nanoporöse Filme mit regelmäßig angeordneten molekularen Motoren für lichtgesteuerte Adsorption und Diffusion.

Author

Jiang, Yunzhe, Danowski, Wojciech, Feringa, Ben L., and Heinke, Lars

Subjects
MOLECULAR motor proteins, ADSORPTION (Chemistry)
Abstract

Keywords: Adsorption; Diffusion; Fotoschalter; Metallorganisches Gerüst; Synthetische Molekulare Motoren DE Adsorption Diffusion Fotoschalter Metallorganisches Gerüst Synthetische Molekulare Motoren 1 1 1 01/11/23 20230116 NES 230116 B Photochromic Materials b . In their Communication (e202214202), Lars Heinke et al. report nanoporous films with oriented arrays of molecular motors for light-controlled adsorption and diffusion. [Extracted from the article]

Published
2023
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175. Frontispiece: Nanoporous Films with Oriented Arrays of Molecular Motors for Photoswitching the Guest Adsorption and Diffusion.

Author

Jiang, Yunzhe, Danowski, Wojciech, Feringa, Ben L., and Heinke, Lars

Subjects
MOLECULAR motor proteins, ADSORPTION (Chemistry), DIFFUSION, METAL-organic frameworks, ALKENES
Abstract

Diffusion, Metal-Organic Framework, Overcrowded Alkene, Photoswitches, Uptake Keywords: Diffusion; Metal-Organic Framework; Overcrowded Alkene; Photoswitches; Uptake EN Diffusion Metal-Organic Framework Overcrowded Alkene Photoswitches Uptake 1 1 1 01/11/23 20230116 NES 230116 B Photochromic Materials b . [Extracted from the article]

Published
2023
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176. Assessing one-dimensional diffusion in nanoporous materials from transient concentration profiles

Author

Heinke, Lars, Kärger, Jörg, Heinke, Lars, and Kärger, Jörg

Abstract

The use of interference microscopy has enabled the direct observation of transient concentration profiles generated by intracrystalline transport diffusion in nanoporous materials. The thus accessible intracrystalline concentration profiles contain a wealth of information which cannot be deduced by any macroscopic method. In this paper, we illustrate five different ways for determining the concentration-dependent diffusivity in one-dimensional systems and two for the surface permeability. These methods are discussed by application to concentration profiles evolving during the uptake of methanol by the zeolite ferrierite and of methanol by the metal organic framework (MOF) manganese(II) formate. We show that the diffusivity can be calculated most precisely by means of Fick’s 1st law. As the circumstances permit, Boltzmann’s integration method also yields very precise results. Furthermore, we present a simple procedure that enables the estimation of the influence of the surface barrier on the overall

Published
2008

179. Metal‐Organic Framework Thin Films Grown on Functionalized Graphene as Solid‐State Ion‐Gated FETs.

Author

Chandresh, Abhinav, Wöll, Christof, and Heinke, Lars

Subjects
*THIN films, *METAL-organic frameworks, *GRAPHENE, *FIELD-effect transistors, *ELECTRONIC equipment, *METALLIC films, *GRAPHENE oxide
Abstract

The unique properties of 2D‐materials like graphene are exploited in various electronic devices. In sensor applications, graphene shows a very high sensitivity, but only a low specificity. This shortcoming can be mastered by using heterostructures, where graphene is combined with materials exhibiting high analyte selectivities. Herein, this study demonstrates the precise deposition of nanoporous metal‐organic frameworks (MOFs) on graphene, yielding bilayers with excellent specificity while the sensitivity remains large. The key for the successful layer‐by‐layer deposition of the MOF films (SURMOFs) is the use of planar polyaromatic anchors. Then, the MOF pores are loaded with ionic liquid (IL). For functioning sensor devices, the IL@MOF films are grown on graphene field‐effect transistors (GFETs). Adding a top‐gate electrode yields an ion‐gated GFET. Analysis of the transistor characteristics reveals a clear Dirac point at low gate voltages, good on‐off ratios, and decent charge mobilities and densities in the graphene channel. The GFET‐sensor reveals a strong and selective response. Compared to other ion‐gated‐FET devices, the IL@MOF material is relatively hard, allowing the manufacturing of ultrathin devices. The new MOF‐anchoring strategy offers a novel approach generally applicable for the functionalization of 2D‐materials, where MOF/2D‐material hetero‐bilayers carry a huge potential for a wide variety of applications. [ABSTRACT FROM AUTHOR]

Published
2023
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