Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orie...Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by measuring the silicon K-edge near edge X-ray absorption fine structure （NEXAFS）. In the NEXAFS spectra of the thin sample, two clear peaks which were assigned to Is → σ^＊Si-N and 1s→ σ^＊Si-Cl appeared around 1847.2 eV and 1843.1 eV respectively. The intensities of the resonance peaks showed strong polarization dependence. A quantitative analysis of the polarization dependence revealed that the Si-N bond tended to lie down while the Si-Cl bond was out of the molecular plane.展开更多
In order to uncover the real origin of red luminescence from Sr_3Al_2O_6：Eu and the physical mechanisms that were involved in the dynamical process of luminescence, variant amount of Eu and Dy activated Sr_3Al_2O_6 p...In order to uncover the real origin of red luminescence from Sr_3Al_2O_6：Eu and the physical mechanisms that were involved in the dynamical process of luminescence, variant amount of Eu and Dy activated Sr_3Al_2O_6 phosphors were synthesized with the solid-state reaction and the combustion-assisted solid-state reaction, respectively, using the fine graphite powder or the mixed H^2＋N_2gases as a reducing agent. The phase was examined with XRD analysis and the photoluminescence properties were characterized by a fluorescence spectrometer. Although the phosphors possessed the same Sr_3Al_2O_6 phase, different emission colors（red or green） were obtained, relying on synthesis conditions. The simultaneous existence of Eu^2＋ and Eu^3＋ was not only observed in the emission and excitation spectra, but also identified with the near edge X-ray absorption fine structure spectroscopy（NEXAFS）.The mixed valence（higher than ＋2 and less than ＋3） of Eu may be related with the six different sites of Sr, whose effective valence ranged from ＋1.5058 to ＋2.2698, in the crystal lattice of Sr_3Al_2O_6 that could accommodate Eu. Moreover, the reduction of Eu^3＋ to forming Eu^2＋ depended on the amount of Eu^3＋ or Dy^3＋ doped, due to the different energy barrier in each site of Sr that Eu had to overcome. The residual Eu^3＋, similar to the doped Dy^3＋, played an important role in supplying the hole for Eu^2＋ to form a bound trap（Eu^2＋）＊ after excitation. During electron returning to the 4f^7 ground state of Eu^2＋, the red luminescence was radiated. Therefore, the synergetic effects of Eu^2＋ and Eu^3＋（Dy^3＋） produce red luminescence.展开更多
基金Nuclear Researchers Exchange Program 2005Photon Factory Program Advisory Committee (2004G340)
文摘Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by measuring the silicon K-edge near edge X-ray absorption fine structure （NEXAFS）. In the NEXAFS spectra of the thin sample, two clear peaks which were assigned to Is → σ^＊Si-N and 1s→ σ^＊Si-Cl appeared around 1847.2 eV and 1843.1 eV respectively. The intensities of the resonance peaks showed strong polarization dependence. A quantitative analysis of the polarization dependence revealed that the Si-N bond tended to lie down while the Si-Cl bond was out of the molecular plane.
基金Project supported by the National High-Tech R&D Program(863 program)(2013AA03A114)the joint funding of National Natural Science Foundation of China and the Chinese Academy of Sciences(U1332133)+3 种基金the Science and Technology Program of Anhui Province of China(1301022062,1301022067)the Special Fund for Research and Development of the Hefei Institute(IMICZ2015112)the Fund of Beijing National Laboratory for Molecular Sciences(20140143)and the Key Discipline of Information and Communication Engineering of University of Science and Technology of Anhui(AKZDXK2015C02)
文摘In order to uncover the real origin of red luminescence from Sr_3Al_2O_6：Eu and the physical mechanisms that were involved in the dynamical process of luminescence, variant amount of Eu and Dy activated Sr_3Al_2O_6 phosphors were synthesized with the solid-state reaction and the combustion-assisted solid-state reaction, respectively, using the fine graphite powder or the mixed H^2＋N_2gases as a reducing agent. The phase was examined with XRD analysis and the photoluminescence properties were characterized by a fluorescence spectrometer. Although the phosphors possessed the same Sr_3Al_2O_6 phase, different emission colors（red or green） were obtained, relying on synthesis conditions. The simultaneous existence of Eu^2＋ and Eu^3＋ was not only observed in the emission and excitation spectra, but also identified with the near edge X-ray absorption fine structure spectroscopy（NEXAFS）.The mixed valence（higher than ＋2 and less than ＋3） of Eu may be related with the six different sites of Sr, whose effective valence ranged from ＋1.5058 to ＋2.2698, in the crystal lattice of Sr_3Al_2O_6 that could accommodate Eu. Moreover, the reduction of Eu^3＋ to forming Eu^2＋ depended on the amount of Eu^3＋ or Dy^3＋ doped, due to the different energy barrier in each site of Sr that Eu had to overcome. The residual Eu^3＋, similar to the doped Dy^3＋, played an important role in supplying the hole for Eu^2＋ to form a bound trap（Eu^2＋）＊ after excitation. During electron returning to the 4f^7 ground state of Eu^2＋, the red luminescence was radiated. Therefore, the synergetic effects of Eu^2＋ and Eu^3＋（Dy^3＋） produce red luminescence.
