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排序方式: 共有218条查询结果,搜索用时 359 毫秒
81.
82.
Dr. Raoul Blume Dr. Wolfram Calvet Dr. Aliakbar Ghafari Dr. Thomas Mayer Dr. Axel Knop-Gericke Prof. Dr. Robert Schlögl 《Chemphyschem》2023,24(23):e202300231
NiOx films on Si(111) were put in contact with oxygen at elevated temperatures. During heating and cooling in oxygen atmosphere Near Ambient Pressure (NAP)-XPS and -XAS and work function (WF) measurements reveal the creation and replenishing of oxygen vacancies in dependence of temperature. Oxygen vacancies manifest themselves as a distinct O1s feature at 528.9 eV on the low binding energy side of the main NiO peak as well as by a distinct deviation of the Ni2p3/2 spectral features from the typical NiO spectra. DFT calculations reveal that the presence of oxygen vacancies leads to a charge redistribution and altered bond lengths of the atoms surrounding the vacancies causing the observed spectral changes. Furthermore, we observed that a broadening of the lowest energy peak in the O K-edge spectra can be attributed to oxygen vacancies. In the presence of oxygen vacancies, the WF is lowered by 0.1 eV. 相似文献
83.
Localized Mixed‐Valence and Redox Activity within a Triazole‐Bridged Dinucleating Ligand upon Coordination to Palladium 下载免费PDF全文
Daniël L. J. Broere Raoul Plessius Dr. Joanne Tory Dr. Serhiy Demeshko Prof. Dr. Bas de Bruin Dr. Maxime A. Siegler Prof. Dr. Frantisek Hartl Dr. Jarl Ivar van der Vlugt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13965-13975
The new dinucleating redox‐active ligand ( LH4 ), bearing two redox‐active NNO‐binding pockets linked by a 1,2,3‐triazole unit, is synthetically readily accessible. Coordination to two equivalents of PdII resulted in the formation of paramagnetic (S= ) dinuclear Pd complexes with a κ2‐N,N′‐bridging triazole and a single bridging chlorido or azido ligand. A combined spectroscopic, spectroelectrochemical, and computational study confirmed Robin–Day Class II mixed‐valence within the redox‐active ligand, with little influence of the secondary bridging anionic ligand. Intervalence charge transfer was observed between the two ligand binding pockets. Selective one‐electron oxidation allowed for isolation of the corresponding cationic ligand‐based diradical species. SQUID (super‐conducting quantum interference device) measurements of these compounds revealed weak anti‐ferromagnetic spin coupling between the two ligand‐centered radicals and an overall singlet ground state in the solid state, which is supported by DFT calculations. The rigid and conjugated dinucleating redox‐active ligand framework thus allows for efficient electronic communication between the two binding pockets. 相似文献
84.
85.
Dr. Morten T. Jarlstad Olesen Dr. Raoul Walther Pier Paolo Poier Frederik Dagnæs-Hansen Dr. Alexander N. Zelikin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7460-7466
In this work, a tumor growth intervention by localized drug synthesis within the tumor volume, using the enzymatic repertoire of the tumor itself, is presented. Towards the overall success, molecular, macromolecular, and supramolecular glucuronide prodrugs were designed for a highly potent toxin, monomethyl auristatin E (MMAE). The lead candidate exhibited a fold difference in toxicity between the prodrug and the drug of 175, had an engineered mechanism to enhance the deliverable payload to tumours, and contained a highly potent toxin such that bioconversion of only a few prodrug molecules created a concentration of MMAE sufficient enough for efficient suppression of tumor growth. Each of these points is highly significant and together afford a safe, selective anticancer measure, making tumor-targeted glucuronides attractive for translational medicine. 相似文献
86.
87.
Schuster ME Hävecker M Arrigo R Blume R Knauer M Ivleva NP Su DS Niessner R Schlögl R 《The journal of physical chemistry. A》2011,115(12):2568-2580
Diesel soot (Euro IV and Euro VI) was investigated with spectroscopic methods such as near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoemission spectroscopy (XPS). C and O K-edge NEXAFS show that structural disorder on the surface is accompanied by a higher amount of oxygen functional groups. O K-edge NEXAFS and O1s XPS results are discussed with the aim to elucidate the nature of the oxygen surface species. The analysis of the data presented here allows the postulation of a hypothetical structure for soot samples emitted by diesel engines. 相似文献
88.
den Hollander MJ Magis JG Fuchsenberger P Aartsma TJ Jones MR Frese RN 《Langmuir : the ACS journal of surfaces and colloids》2011,27(16):10282-10294
The utilization of proteins as nanodevices for solar cells, bioelectronics, and sensors generally necessitates the transfer of electrons to or from a conducting material. Here we report on efforts to maximize photocurrent generation by bacterial photosynthetic reaction center pigment-protein complexes (RCs) interfaced with a metal electrode. The possibility of adhering RCs to a bare gold electrode was investigated with a view to minimizing the distance for electron tunneling between the protein-embedded electron-transfer cofactors and the metal surface. Substantial photocurrents were achieved despite the absence of coating layers on the electrode or engineered linkers to achieve the oriented deposition of RCs on the surface. Comparison with SAM-covered gold electrodes indicating enhanced photocurrent densities was achieved because of the absence of an insulating layer between the photoactive pigments and the metal. Utilizing RCs surrounded by light-harvesting 1 complex resulted in higher photocurrents, surprisingly not due to enhanced photoabsorption but likely due to better surface coverage of uniformly oriented RC-LH1 complexes and the presence of a tetraheme cytochrome that could act as a connecting wire. The introduction of cytochrome-c (cyt-c) as a molecular relay also produced increases in current, probably by intercalating between the adhered RCs or RC-LH1 complexes and the electrode to mediate electron transfer. Varying the order in which components were introduced to the electrode indicated that dynamic rearrangements of RCs and cyt-c occurred at the bare metal surface. An upper limit for current generation could not be detected within the range of the illumination power available, with the maximum current density achieved by RC-LH1 complexes being on the order of 25 μA/cm(2). High currents could be generated consecutively for several hours or days under ambient conditions. 相似文献
89.
Mens R Chambon S Bertho S Reggers G Ruttens B D'Haen J Manca J Carleer R Vanderzande D Adriaensens P 《Magnetic resonance in chemistry : MRC》2011,49(5):242-247
PCBM or [6,6]-phenyl-C(61)-butyric acid methyl ester is nowadays still one of the most successful electron acceptors for plastic bulk heterojunction (BHJ) photovoltaic devices. In this study, a set of complementary techniques, i.e. solid-state NMR, XRD and DSC, is proposed as a fast and sensitive tool to screen the morphology of PCBM specimens with different preparation histories. Based on proton NMR relaxation decay time values, an interval can be derived that situates the average crystal dimensions and which can further be refined on the basis of XRD patterns and DSC thermograms. 相似文献
90.
Raoul Bourquin Vasile Gradinaru George A. Hagedorn 《Journal of mathematical chemistry》2012,50(3):602-619
We present a review of rigorous mathematical results about non-adiabatic transitions in molecular systems that are associated
with avoided crossings of electron energy level surfaces. We then present a novel numerical technique for studying these transitions
that is based on expansions in semiclassical wavepackets. 相似文献