This paper reports how pyrite films were prepared by thermal sulfurization of magnetron sputtered iron films and characterized by X-ray absorption near edge structure spectra and X-ray photoelectron spectroscopy on a ...This paper reports how pyrite films were prepared by thermal sulfurization of magnetron sputtered iron films and characterized by X-ray absorption near edge structure spectra and X-ray photoelectron spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation Facility. The band gap of the pyrite agrees well with the optical band gap obtained by a spectrophotometer. The octahedral symmetry of pyrite leads to the splitting of the d orbit into t2g and eg levels. The high spin and low spin states were analysed through the difference of electron exchange interaction and the orbital crystal field. Only when the crystal field splitting is higher than 1.5 eV, the two weak peaks above the white lines can appear, and this was approved by experiments in the present work.展开更多
The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS s...The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS spectra of these adsorption configurations have been calculated by using the density functional theory(DFT)method and fullcore hole(FCH)approximation to investigate the relationship between the adsorption configurations and the spectra.The result shows that the XPS and NEXAFS spectra are structurally dependent on the configurations of pyrrole absorbed on the Si(100)surface.Compared with the XPS,the NEXAFS spectra are relatively sensitive to the adsorption configurations and can accurately identify them.The NEXAFS decomposition spectra produced by non-equivalent carbon atoms have also been calculated and show that the spectral features vary with the diverse types of carbon atoms and their structural environments.展开更多
We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopro...We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopropylsilyl ethynylene (HZ-TIPS) and its homologue,octazethrene (OZ-TIPS) on an all-inorganic perovskite cesium lead bromide (CsPbBr3) surface.The photoluminescence behavior of the underlying perovskites upon differing molecular doping conditions was examined.It turns out that the charge transfer dynamics of thermally-evaporated OZ-TIPS molecule exhibited a faster average lifetime than that of the HZ-TIPS case suggesting the importance of the biradical state in the former molecule.An interfacial dipole was formed at the interface due to the competing interaction between the dispersion force of the bulky TIPS-substituent group and the attractive van der Waals interaction at the first few layers.Photoemission spectroscopy of the physisorbed HZ-TIPS shows chemical shifts,which indicates electron transfer from HZ-TIPS molecules to the CsPbBr3 perovskite single crystal.In contrast,the adsorbed OZ-TIPS molecular layer on CsPbBr3 demonstrates the opposite trend indicating a hole transfer process.The average molecular orientation as determined by near edge X-ray absorption fine structure (NEXAFS) suggests that the HZ-TIPS molecular plane is generally lifted with respect to the perovskite surface.We suggest that the nature of the closed-shell electronic ground state of HZ-TIPS could contribute to the formation of interfacial dipole at the molecule/perovskite interface.展开更多
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
This work presents an extreme biomimetics route for the creation of nano- structured biocomposites utilizing a chitinous template of poriferan origin. The specific thermal stability of the nanostructured chitinous tem...This work presents an extreme biomimetics route for the creation of nano- structured biocomposites utilizing a chitinous template of poriferan origin. The specific thermal stability of the nanostructured chitinous template allowed for the formation under hydrothermal conditions of a novel germanium oxide- chitin composite with a defined nanoscale structure. Using a variety of analytical techniques （FTIR, Raman, energy dispersive X-ray （EDX）, near-edge X-ray absorption fine structure （NEXAFS）, and photoluminescence （PL） spectroscopy, EDS-mapping, selected area for the electron diffraction pattern （SAEDP）, and transmission electron microscopy （TEM））, we showed that this bioorganic scaffold induces the growth of GeO2 nanocrystals with a narrow （150-300 nm） size distri- bution and predominantly hexagonal phase, demonstrating the chitin template＇s control over the crystal morphology. The formed GeO2-chitin composite showed several specific physical properties, such as a striking enhancement in photo- luminescence exceeding values previously reported in GeOR-based biomaterials. These data demonstrate the potential of extreme biomimetics for developing new-generation nanostructured materials.展开更多
As part of an effort to build a prototype flow battery system using a nano-suspension containing β-Ni（OH）2 nanoparticles as the cathode material, nano-sized β-Ni（OH）2 particles with well-controlled particle size...As part of an effort to build a prototype flow battery system using a nano-suspension containing β-Ni（OH）2 nanoparticles as the cathode material, nano-sized β-Ni（OH）2 particles with well-controlled particle size and morphology were synthesized via the one-step precipitation of a NiCl2 precursor. The composition and morphology of the nanoparticles were characterized by scanning electronic microscopy （SEM） and X-ray diffraction （XRD）. The XRD patterns confirmed that β-Ni（OH）2 was successfully synthesized, while SEM results showed that the particle sizes range from 70 to 150 nm. To ensure that Ni（OH）2 could be employed in the nano-suspension flow battery, the electrochemical performance of the synthesized 13-Ni（OH）2 was initially tested in pouch cells through charge/discharge cycling. The phase transformations occurring during charge/discharge were investigated using in-situ X-ray absorption spectroscopy to obtain the shift in the oxidation state of Ni （X-ray adsorption near edge structure, XANES） and the distances between Ni and surrounding atoms in charged and discharged states （extended X-ray absorption fine structure, EXAFS）. XANES results indicated that the electrode in the discharged state was a mixture of phases because the edge position did not shift back completely. XAFS results further proved that the discharge capacity was provided by β-NiOOH and the ratio between β-Ni（OH）2 and γ-NiOOH in the electrode in the discharged state was 71：29. Preliminary nano-suspension tests in a lab-scale cell were conducted to understand the behavior of the nano-suspension during charge/discharge cycling and to optimize the operating conditions.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Project supported by the National Natural Science Foundation of China (Grant No 102750770)
文摘This paper reports how pyrite films were prepared by thermal sulfurization of magnetron sputtered iron films and characterized by X-ray absorption near edge structure spectra and X-ray photoelectron spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation Facility. The band gap of the pyrite agrees well with the optical band gap obtained by a spectrophotometer. The octahedral symmetry of pyrite leads to the splitting of the d orbit into t2g and eg levels. The high spin and low spin states were analysed through the difference of electron exchange interaction and the orbital crystal field. Only when the crystal field splitting is higher than 1.5 eV, the two weak peaks above the white lines can appear, and this was approved by experiments in the present work.
基金Project supported by the Shandong Provincial Natural Science Foundation,China(Grant Nos.ZR2022MA025 and ZR2020MA077).
文摘The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS spectra of these adsorption configurations have been calculated by using the density functional theory(DFT)method and fullcore hole(FCH)approximation to investigate the relationship between the adsorption configurations and the spectra.The result shows that the XPS and NEXAFS spectra are structurally dependent on the configurations of pyrrole absorbed on the Si(100)surface.Compared with the XPS,the NEXAFS spectra are relatively sensitive to the adsorption configurations and can accurately identify them.The NEXAFS decomposition spectra produced by non-equivalent carbon atoms have also been calculated and show that the spectral features vary with the diverse types of carbon atoms and their structural environments.
文摘We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopropylsilyl ethynylene (HZ-TIPS) and its homologue,octazethrene (OZ-TIPS) on an all-inorganic perovskite cesium lead bromide (CsPbBr3) surface.The photoluminescence behavior of the underlying perovskites upon differing molecular doping conditions was examined.It turns out that the charge transfer dynamics of thermally-evaporated OZ-TIPS molecule exhibited a faster average lifetime than that of the HZ-TIPS case suggesting the importance of the biradical state in the former molecule.An interfacial dipole was formed at the interface due to the competing interaction between the dispersion force of the bulky TIPS-substituent group and the attractive van der Waals interaction at the first few layers.Photoemission spectroscopy of the physisorbed HZ-TIPS shows chemical shifts,which indicates electron transfer from HZ-TIPS molecules to the CsPbBr3 perovskite single crystal.In contrast,the adsorbed OZ-TIPS molecular layer on CsPbBr3 demonstrates the opposite trend indicating a hole transfer process.The average molecular orientation as determined by near edge X-ray absorption fine structure (NEXAFS) suggests that the HZ-TIPS molecular plane is generally lifted with respect to the perovskite surface.We suggest that the nature of the closed-shell electronic ground state of HZ-TIPS could contribute to the formation of interfacial dipole at the molecule/perovskite interface.
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.
文摘This work presents an extreme biomimetics route for the creation of nano- structured biocomposites utilizing a chitinous template of poriferan origin. The specific thermal stability of the nanostructured chitinous template allowed for the formation under hydrothermal conditions of a novel germanium oxide- chitin composite with a defined nanoscale structure. Using a variety of analytical techniques （FTIR, Raman, energy dispersive X-ray （EDX）, near-edge X-ray absorption fine structure （NEXAFS）, and photoluminescence （PL） spectroscopy, EDS-mapping, selected area for the electron diffraction pattern （SAEDP）, and transmission electron microscopy （TEM））, we showed that this bioorganic scaffold induces the growth of GeO2 nanocrystals with a narrow （150-300 nm） size distri- bution and predominantly hexagonal phase, demonstrating the chitin template＇s control over the crystal morphology. The formed GeO2-chitin composite showed several specific physical properties, such as a striking enhancement in photo- luminescence exceeding values previously reported in GeOR-based biomaterials. These data demonstrate the potential of extreme biomimetics for developing new-generation nanostructured materials.
文摘As part of an effort to build a prototype flow battery system using a nano-suspension containing β-Ni（OH）2 nanoparticles as the cathode material, nano-sized β-Ni（OH）2 particles with well-controlled particle size and morphology were synthesized via the one-step precipitation of a NiCl2 precursor. The composition and morphology of the nanoparticles were characterized by scanning electronic microscopy （SEM） and X-ray diffraction （XRD）. The XRD patterns confirmed that β-Ni（OH）2 was successfully synthesized, while SEM results showed that the particle sizes range from 70 to 150 nm. To ensure that Ni（OH）2 could be employed in the nano-suspension flow battery, the electrochemical performance of the synthesized 13-Ni（OH）2 was initially tested in pouch cells through charge/discharge cycling. The phase transformations occurring during charge/discharge were investigated using in-situ X-ray absorption spectroscopy to obtain the shift in the oxidation state of Ni （X-ray adsorption near edge structure, XANES） and the distances between Ni and surrounding atoms in charged and discharged states （extended X-ray absorption fine structure, EXAFS）. XANES results indicated that the electrode in the discharged state was a mixture of phases because the edge position did not shift back completely. XAFS results further proved that the discharge capacity was provided by β-NiOOH and the ratio between β-Ni（OH）2 and γ-NiOOH in the electrode in the discharged state was 71：29. Preliminary nano-suspension tests in a lab-scale cell were conducted to understand the behavior of the nano-suspension during charge/discharge cycling and to optimize the operating conditions.
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.
