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91.
Jianwei Tong Prof. Dr. Jürgen Köhler Arndt Simon Changhoon Lee Myung‐Hwan Whangbo 《无机化学与普通化学杂志》2012,638(11):1792-1795
Orchid colored powder samples of Cs2AgF4 were prepared by a solid state reaction from CsF and AgF2. The diffuse reflectance spectrum of a powder sample of Cs2AgF4 was measured in the UV/Vis region. It shows three broad bands, two in the visible‐light region at 650 nm, 500 nm and one in the UV region at 259 nm. The bands are assigned to F 2p → Ag 4d and Ag 4d → Ag 4d transitions. The optical band gap for Cs2AgF4 determined from the UV/Vis diffuse reflectance spectrum is approx. 2.17 eV. In order to interpret the observed absorptions, the theoretical absorption spectrum of Cs2AgF4 was obtained from density functional calculations. 相似文献
92.
Schlueter JA Wiehl L Park H de Souza M Lang M Koo HJ Whangbo MH 《Journal of the American Chemical Society》2010,132(46):16308-16310
Single-crystal X-ray diffraction has shown that the high-critical-temperature (T(c)) phase of the filamentary molecular superconductor (BEDT-TTF)(2)Ag(CF(3))(4)(1,1,2-trichloroethane) [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] contains layers of BEDT-TTF radical cations with alternating κ- and α'-type packing motifs. This molecule-based superconductor with dual BEDT-TTF packing motifs has a T(c) five times higher than that of its polymorph that contains only κ-type packing. 相似文献
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94.
How indices of refraction n(omega) of insulating solids are affected by the volume dilution of an optical entity and the mixing of different, noninteracting simple solid components was examined on the basis of the dielectric function epsilon(1)(omega) + iepsilon(2)(omega). For closely related insulating solids with an identical composition and the formula unit volume V, the relation [epsilon(1)(omega) - 1]V = constant was found by combining the relation epsilon(2)(omega)V = constant with the Kramers-Kronig relation. This relation becomes [n(2)(omega) - 1]V = constant for the index of refraction n(omega) determined for the incident light with energy less than the band gap (i.e., h omega < E(g)). For a narrow range of change in the formula unit volume, the latter relation is well approximated by a linear relation between n and 1/V. 相似文献
95.
The misfit layer compounds (LaS)1.14(NbS2)n (n=1, 2) and [(Pb,Sb)S]1.14NbS2 were examined by scanning tunneling microscopy (STM) and atomic force microscopy (AFM). In these compounds the NaCl-type double MS (M=La, Pb, Sb) layers (Q layers) alternate with the NbS2 layers (H layers) made up of NbS6 trigonal prisms. It was possible to record AFM and STM images for only the H layers for (LaS)1.14(NbS2)n, but for both the H- and Q-layers for [(Pb,Sb)S]1.14NbS2. Partial and total electron density plots of the H and Q layers were calculated to interpret the observed STM and AFM images. The bright spots in the STM and AFM images of the H layer correspond to S atoms, and those of the Q layer to Pb and Sb atoms. The STM images for the Q layers of [(Pb,Sb)S]1.14NbS2 suggest that a short-range ordering of the Pb and Sb atoms occurs in the (Pb,Sb)S sheets of the Q layer. 相似文献
96.
Rnald David Houria Kabbour Alain Pautrat Nadia Touati Myung‐Hwan Whangbo Olivier Mentr 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(12):3175-3178
The quest for new oxides with cations containing active lone‐pair electrons (E) covers a broad field of targeted specificities owing to asymmetric electronic distribution and their particular band structure. Herein, we show that the novel compound BaCoAs2O5, with lone‐pair As3+ ions, is built from rare square‐planar Co2+O4 involved in direct bonding between As3+E and Co2+ dz2 orbitals (Co As=2.51 Å). By means of DFT and Hückel calculations, we show that this σ‐type overlapping is stabilized by a two‐orbital three‐electron interaction allowed by the high‐spin character of the Co2+ ions. The negligible experimental spin‐orbit coupling is expected from the resulting molecular orbital scheme in O3AsE–CoO4 clusters. 相似文献
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Amorphous C-Si-O particles, prepared by pyrolyzing PDMS in a horizontal furnace using the carrier gas N2/H2 at 900 °C, were characterized by electron microscopy, X-ray diffraction, FTIR spectroscopy, X-ray photoelectron spectroscopy and fluorescence spectroscopy. The particles possess four luminescence peaks at 440, 465, 533 and 620 nm, and produce stable red, green or blue light emissions at room temperature when irradiated with appropriate wavelengths, the four peaks attribute to different defect centers in the particles. And the particles exhibit the highest photoluminescence intensity when annealed at 600 °C. 相似文献