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991.
Feiyu Zhao Xue Luo Lixiang Liu Jianhang Lv Prof. Xianping Fan Dr. Xvsheng Qiao Prof. Yang Xu Prof. Lorenz Kienle Prof. Xianghua Zhang Prof. Guodong Qian 《Chemphyschem》2020,21(5):397-405
GeSe micro-sheets and micro-belts have been synthesized by a facile one-pot wet chemical method in 1-octadecene solvent and oleic acid solvent, respectively. The adsorption of more oleic acid molecules on the (002) plane promoted growth along [010] direction of the GeSe micro-belts and limited carrier transport in this direction, resulting in higher carrier concentration and mobility of the GeSe micro-belts. The performance of the photodetectors based on the single GeSe micro-sheet and the single GeSe micro-belt was investigated under illumination at 532 nm, 980 nm and 1319 nm. Both, photodetectors based on a single GeSe micro-sheet and a single GeSe micro-belt, exhibit a high photoresponse, short response/recovery times, and long-term durability. Moreover, the photodetector based on a single GeSe micro-belt displays a broadband response with a high responsivity (5562 A/W at 532 nm, 1546 A/W at 980 nm) and detectivity (3.01×1012 Jones at 532 nm, 8.38×1011 Jones at 980 nm). These excellent characteristics render single GeSe micro-belts very interesting for use as highly efficient photodetectors, especially in the NIR region. 相似文献
992.
Alice L. Dauphin Dr. Stéphane Arbault Prof. Dr. Alexander Kuhn Prof. Dr. Neso Sojic Dr. Laurent Bouffier 《Chemphyschem》2020,21(7):600-604
We propose a straightforward access to a rotating light-emitting device powered by wireless electrochemistry. A magnetic stirrer is used to rotate a light-emitting diode (LED) due to the intrinsic magnetic properties of the tips that contain iron. At the same time, the LED is submitted to an electric field and acts as a bipolar electrode. The electrochemical processes that are coupled on both extremities of the LED drive an electron flow across the device, resulting in light emission. The variation of the LED alignment in time enables an alternating light emission that is directly controlled by the rotation rate. The stirring also enables a continuous mixing of the electrolyte that improves the stability of the output signal. Finally, the LED brightness can readily reveal a change of chemical composition in the electrolyte solution. 相似文献
993.
Akihiro Kitashoji Kosei Kitagawa Dr. Akimasa Fujihara Prof. Dr. Tomoyuki Yatsuhashi 《Chemphyschem》2020,21(9):847-852
A multiply charged molecule expands the range of a mass window and is utilized as a precursor to provide rich sequence coverage; however, reflectron time-of-flight mass spectrometer has not been well applied to the product ion analysis of multiply charged precursor ions. Here, we demonstrate that the range of the mass-to-charge ratio of measurable product ions is limited in the cases of multiply charged precursor ions. We choose C6F6 as a model molecule to investigate the reactions of multiply charged molecular cations formed in intense femtosecond laser fields. Measurements of the time-of-flight spectrum of C6F6 by changing the potential applied to the reflectron, combined with simulation of the ion trajectory, can identify the species detected behind the reflectron as the neutral species and/or ions formed by the collisional charge transfer. Moreover, the metastable ion dissociations of doubly and triply charged C6F6 are identified. The detection of product ions in this manner can diminish interference by the precursor ion. Moreover, it does not need precursor ion separation before product ion analysis. These advantages would expand the capability of mass spectrometry to obtain information about metastable ion dissociation of multiply charged species. 相似文献
994.
Risa Fukuzumi Dr. Satoshi Kaneko Shintaro Fujii Prof. Tomoaki Nishino Dr. Manabu Kiguchi 《Chemphyschem》2020,21(4):274-274
The front cover artwork was provided by the group of Prof. Nishino, Tokyo Institute of Technology. The image depicts the investigation of the structure and electron transport of the Au, Ag, Cu, Ni, Fe, and Pd atomic junctions doped with dichloroethylene. Read the full text of the Article at 10.1002/cphc.201900988 . 相似文献
995.
Dr. Louwanda Lakiss Dr. Aurélie Vicente Prof. Jean-Pierre Gilson Dr. Valentin Valtchev Dr. Svetlana Mintova Dr. Alexandre Vimont Dr. Robert Bedard Dr. Suheil Abdo Dr. Jeffery Bricker 《Chemphyschem》2020,21(16):1873-1881
We outline two methodologies to selectively characterize the Brønsted acidity of the external surface of FAU-type zeolites by IR and NMR spectroscopy of adsorbed basic probe molecules. The challenge and goal are to develop reliable and quantitative IR and NMR methodologies to investigate the accessibility of acidic sites in the large pore FAU-type zeolite Y and its mesoporous derivatives often referred to as ultra-stable Y (USY). The accessibility of their Brønsted acid sites to probe molecules (n-alkylamines, n-alkylpyridines, n-alkylphosphine- and phenylphosphine-oxides) of different molecular sizes is quantitatively monitored either by IR or 31P NMR spectroscopy. It is now possible, for the first time to quantitatively discriminate between the Brønsted acidity located in the microporosity and on the external surface of large pore zeolites. For instance, the number of external acid sites on a Y (LZY-64) zeolite represents 2 % of its total acid sites while that of a USY (CBV760) represents 4 % while the latter has a much lower framework Si/Al ratio. 相似文献
996.
Dr. Ivan Fernandez-Corbaton Dominik Beutel Prof. Dr. Carsten Rockstuhl Ansgar Pausch Prof. Dr. Wim Klopper 《Chemphyschem》2020,21(9):878-887
We outline a methodology for efficiently computing the electromagnetic response of molecular ensembles. The methodology is based on the link that we establish between quantum-chemical simulations and the transfer matrix (T-matrix) approach, a common tool in physics and engineering. We exemplify and analyze the accuracy of the methodology by using the time-dependent Hartree-Fock theory simulation data of a single chiral molecule to compute the T-matrix of a cross-like arrangement of four copies of the molecule, and then computing the circular dichroism of the cross. The results are in very good agreement with full quantum-mechanical calculations on the cross. Importantly, the choice of computing circular dichroism is arbitrary: Any kind of electromagnetic response of an object can be computed from its T-matrix. We also show, by means of another example, how the methodology can be used to predict experimental measurements on a molecular material of macroscopic dimensions. This is possible because, once the T-matrices of the individual components of an ensemble are known, the electromagnetic response of the ensemble can be efficiently computed. This holds for arbitrary arrangements of a large number of molecules, as well as for periodic or aperiodic molecular arrays. We identify areas of research for further improving the accuracy of the method, as well as new fundamental and technological research avenues based on the use of the T-matrices of molecules and molecular ensembles for quantifying their degrees of symmetry breaking. We provide T-matrix-based formulas for computing traditional chiro-optical properties like (oriented) circular dichroism, and also for quantifying electromagnetic duality and electromagnetic chirality. The formulas are valid for light-matter interactions of arbitrarily-high multipolar orders. 相似文献
997.
Sublimation enthalpies of alkane-α,ω-diamines exhibit an odd-even pattern within their homologous series. First-principles calculations coupled with the quasi-harmonic approximation for crystals and with the conformation mixing model for the ideal gas are used to explain this phenomenon from the theoretical point of view. Crystals of the odd and even alkane-α,ω-diamines distinctly differ in their packing motifs. However, first-principles calculations indicate that it is a delicate interplay of the cohesive forces, phonons, molecular vibrations and conformational equilibrium which governs the odd-even pattern of the sublimation enthalpies within the homologous series. High molecular flexibility of the alkane-α,ω-diamines predetermines higher sensitivity of the computational model to the quality of the optimized geometries and relative conformational energies. Performance of high-throughput computational methods, such as the density functional tight binding (DFTB, GFN2-xTB) and the explicitly correlated dispersion-corrected Møller - Plesset perturbative method (MP2C-F12), are benchmarked against the consistent state-of-the-art calculations of conformational energies and interaction energies, respectively. 相似文献
998.
Philipp Wilhelm Dominik Blank Prof. John M. Lupton Dr. Jan Vogelsang 《Chemphyschem》2020,21(10):961-965
Controlling the morphology of π-conjugated polymers for organic optoelectronic devices has long been a goal in the field of materials science. Since the morphology of a polymer chain is closely intertwined with its photophysical properties, it is desirable to be able to change the arrangement of the polymers at will. We investigate the π-conjugated polymer poly(9,9-dioctylfluorene) (PFO), which can exist in three distinctly different structural phases: the α-, β-, and γ-phase. Every phase has a different chain structure and a unique photoluminescence (PL) spectrum. Due to its unique properties and the pronounced spectral structure-property relations, PFO can be used as a model system to study the morphology of π-conjugated polymers. To avoid ensemble averaging, we examine the PL spectrum of single PFO chains embedded in a non-fluorescent matrix. With single-molecule spectroscopy the structural phase of every single chain can be determined, and changes can be monitored very easily. To manipulate the morphology, solvent vapor annealing (SVA) was applied, which leads to a diffusion of the polymer chains in the matrix. The β- and γ-phases appear during the self-assembly of single α-phase PFO chains into mesoscopic aggregates. The extent of β- and γ-phase formation is directed by the solvent-swelling protocol used for aggregation. Aggregation unequivocally promotes formation of the more planar β- and γ-phases. Once these lower-energy more ordered structural phases are formed, SVA cannot return the polymer chain to the less ordered phase by aggregate swelling. 相似文献
999.
Mr. Kingshuk Mukhuti Dr. V. N. K. B. Adusumalli Mr. Heramba V. S. R. M. Koppisetti Prof. Bhavtosh Bansal Prof. Venkataramanan Mahalingam 《Chemphyschem》2020,21(15):1731-1736
Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures. In this paper, we demonstrate a strategy to pass through this bottleneck by designing a linear colorimetric thermometer by which we could estimate down to 4 K. The change in perceptual color fidelity metric provides an accurate measure for the sensitivity of the thermometer that attains a maximum value of 0.86 K−1. Thermally coupled states in Er3+ are also used as a ratiometric sensor from room temperature to ∼140 K. The results obtained in this work clearly show that Yb3+−Er3+ co-doped NaGdF4 microcrystals are a promising system that enables reliable bimodal thermometry in a very wide temperature range from ultralow (4 K) to ambient (290 K) conditions. 相似文献
1000.
Prof. Dr. Igor Savić Prof. Dr. Stephan Schlemmer Prof. Dr. Dieter Gerlich 《Chemphyschem》2020,21(13):1429-1435
In order to study collisions between ions and neutrals, a new Guided Ion Beam (GIB) apparatus, called NOVion, has been assembled and tested. The primary purpose of this instrument is to measure absolute cross sections at energies relevant for technical or inter- and circumstellar plasmas. New and improved results are presented for forming H3+ in collisions of H2+ with H2. Between 0.1 eV and 2 eV, our measured effective cross sections are in good overall agreement with most previous measurements. However, at higher energies, our results do not show the steep decline, recommended in the standard literature. After critical evaluation of all experimental and theoretical data, a new analytical function is proposed, describing properly the dependence of the title reaction on the collision energy up to 10 eV. 相似文献