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排序方式: 共有7739条查询结果,搜索用时 15 毫秒
911.
Dr. Silvia Castro-Fernández Carlos M. Cruz Dr. Inês F. A. Mariz Dr. Irene R. Márquez Vicente G. Jiménez Lucía Palomino-Ruiz Prof. Juan M. Cuerva Dr. Ermelinda Maçôas Dr. Araceli G. Campaña 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(18):7205-7211
A new family of distorted ribbon-shaped nanographenes was designed, synthesized, and their optical and electrochemical properties were evaluated, pointing out an unprecedented correlation between their structural characteristics and the two-photon absorption (TPA) responses and electrochemical band gaps. Three nanographene ribbons have been prepared: a seven-membered-ring-containing nanographene presenting a tropone moiety at the edge, its full-carbon analogue, and a purely hexagonal one. We have found that the TPA cross-sections and the electrochemical band gaps of the seven-membered-ring-containing compounds are higher and lower, respectively, than those of the fully hexagonal polycyclic aromatic hydrocarbon (PAH). Interestingly, the inclusion of additional curvature has a positive effect in terms of non-linear optical properties of those ribbons. 相似文献
913.
Maksim Kulichenko Nikita Fedik Prof. Dr. Konstatin V. Bozhenko Prof. Dr. Alexander I. Boldyrev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5311-5315
Growing demands of material science and, in particular, in the field of nonlinear optics (NLO) encourage us to look for stable highly polarizable molecules with excess diffuse electrons. An unusual class of compounds called electrides comply with these requirements. Many attempts have been made, yet only few electrides have been synthesized as solids and none of them as molecular species. In this paper, a new theoretically designed molecular species with electride characteristics is reported. The idea of this molecular electride comes from the formation of electride-like features in the MgO crystal with defect F-centers. The geometry of the investigated molecule can be described as a Mg4O4 cube with one oxygen atom removed. In Mg4O3, two 3s electrons are pushed out from the inner area of the molecule forming a diffuse electride multicentered bond. Our calculations show that this electride-like cluster possesses a noticeably large first hyperpolarizability β=5733 au. At the same time, a complete cube Mg4O4 and Mg4O32+ without electride electron pair have much smaller β: 0 au and 741 au, respectively. This fact indicates the decisive role of the electride electron pair in NLO properties. Additionally, vertical detachment energies of isomers (VDE), excitation energies ΔE, polarizabilities α, and IR spectra were calculated. These properties, including β, are supposed to be observable experimentally and can serve as indirect evidence of the stable molecular electride formation. 相似文献
914.
Back Cover: Covalent Modification of Graphene Oxide with Carbazole Groups for Laser Protection (Chem. Eur. J. 12/2015)
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915.
Bin‐Wen Liu Xiao‐Ming Jiang Bing‐Xuan Li Hui‐Yi Zeng Guo‐Cong Guo 《Angewandte Chemie (International ed. in English)》2020,59(12):4856-4859
A large nonlinear optical (NLO) coefficient and a wide band gap are two crucial but contradictory parameters that are difficult to achieve simultaneously in a single infrared (IR) NLO compound. A salt‐inclusion chalcogenide (SIC), Li[LiCs2Cl][Ga3S6] ( 1 ), was prepared that presents a nanosized tunnel framework constructed from monotype chalcogenide tetrahedra. Highly oriented covalent GaS4 tetrahedra in the host lead to a moderate second harmonic generation response (0.7 AgGaS2), and ionic guests effectively broaden the band gap to the widest value (4.18 eV) among all IR NLO chalcogenides, thereby achieving a remarkable balance between NLO efficiency and band gap. 相似文献
916.
Motohiro Suzuki Yuichi Inubushi Makina Yabashi Tetsuya Ishikawa 《Journal of synchrotron radiation》2014,21(3):466-472
A diamond phase retarder was applied to control the polarization states of a hard X‐ray free‐electron laser (XFEL) in the photon energy range 5–20 keV. The horizontal polarization of the XFEL beam generated from the planar undulators of the SPring‐8 Angstrom Compact Free‐Electron Laser (SACLA) was converted into vertical or circular polarization of either helicity by adjusting the angular offset of the diamond crystal from the exact Bragg condition. Using a 1.5 mm‐thick crystal, a high degree of circular polarization, 97%, was obtained for 11.56 keV monochromatic X‐rays, whereas the degree of vertical polarization was 67%, both of which agreed with the estimations including the energy bandwidth of the Si 111 beamline monochromator. 相似文献
917.
Yinlong Du Shuling Zhang Xu Jiang Kai Zhu Zhi Geng Yu Fang Pengfei Huo Chuan Liu Yinglin Song Guibin Wang 《Journal of polymer science. Part A, Polymer chemistry》2014,52(9):1282-1290
A series of novel soluble poly(aryl ether ketone)s (PAEKs) based on 5,10‐bis(4‐hydroxyphenyl)?15,20‐diphenylporphyrin (cis‐DHTPP), 4,4′‐(hexafluoroisopropylidene) diphenol (6FBPA) and 4,4′‐difluorobenzophenone (DFB) were synthesized and characterized by FT‐IR, 1H‐NMR, UV–vis and fluorescence spectroscopies. The intrinsic photophysical properties of porphyrins were preserved because of the absence of photoinduced electron transfer in the polymer chains. Investigation of the copolymers thermal properties indicated that these polymers had high glass transition temperatures and excellent thermal stabilities. The results of Z‐scan and optical limiting measurements manifested that incorporation of the porphyrin chromophore into the main chain engendered the novel PAEKs with superior nonlinear optical properties and optical limiting function, which could be effectively tuned by varying the molar ratio of porphyrin monomers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1282–1290 相似文献
918.
《Wave Motion》2015
We present the study of the wave motion in the Talbot interferometer with an additional element such as a lens for all related audiences. Our solutions are in the analytic form. A general principle of the Talbot effect, which is the optical near-field effect, is the Fresnel diffraction. The Fresnel integral is rather complicated. We therefore introduce an alternative method which is based on the wave propagation through the transmission functions of the grating and the lens. Our method has been proved by a simple experimental setup. 相似文献
919.
Measurement of integrated luminosities at BESIII for data samples at center-of-mass energies between 4.0 and 4.6 GeV
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《中国物理C(英文版)》2022,46(11):113002-113002-11
The integrated luminosities of data samples collected in the BESIII experiment in 2016–2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010–2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur. 相似文献
920.
Xinyue Li Sergey Semin Leandro A. Estrada Chunqing Yuan Yulong Duan Jonathan Cremers Paul Tinnemans Paul Kouwer Alan E. Rowan Theo Rasing Jialiang Xu 《中国化学快报》2018,29(2):297-300
The polymorphs of a phenylethynyl functionalized fluorenone derivative, and their controlled self-assembly for microstructures with different morphologies have been studied. These polymorphic microcrystals exhibit very distinctive NLO properties, which are highly correlated to their electronic and supramolecular structures. 相似文献