The protonation effects on one- and two-photon absorption properties of an octupolar molecule TA with 1,3,5-triazine core and pyrrole electron-donating end-groups have been studied at hybrid density functional theory ...The protonation effects on one- and two-photon absorption properties of an octupolar molecule TA with 1,3,5-triazine core and pyrrole electron-donating end-groups have been studied at hybrid density functional theory level. A computational scheme is developed to simulate a proton attached to an atom. The numerical results show that large changes in both one- and two-photon absorption properties are observed when the compound is transformed from neutral to threefold protonated states. When the compound is protonated, more charge transfer states appear and the absorption band has a red-shift. Furthermore, the two-photon absorption cross-section is largely enhanced. The theoretical calculations demonstrate the protonation effect on promoting the intramolecular charge transfer strength. The results present qualitative agreement with the experimental observations. A two-photon absorption switch with the compound TA based on the protonation effect is proposed.展开更多
Single particle mass spectrometry has been widely used to determine the size and chemical compositions of at- mospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this ...Single particle mass spectrometry has been widely used to determine the size and chemical compositions of at- mospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this study, two methods were developed for determining aerosol effective density by a single particle aerosol mass spectrometer （SPAMS）. Method I retrieved effective density through comparison between measured light scattering intensities and Mie theoretical modelled par- tial scattering cross section. Method Ⅱ coupled a differential mobility analyzer （DMA） with SPAMS to simultaneously deter- mine the electric mobility and vacuum aerodynamic diameter, and thus the effective density. Polystyrene latex spheres, ammo- nium sulfate and sodium nitrate were tested by these methods to help validate their effectiveness for determining the aerosol effective density. This study effectively extends SPAMS measurements to include particle size, chemical composition, light scattering, and effective density, and thus helps us better understand the environment and climate effects of aerosols.展开更多
Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from expe...Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.展开更多
The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By usin...The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.展开更多
The structural, electronic and spectroscopic properties of monomer FPt (2-(4′,6′-difluorophenyl)pyridinato-N,C2′)(2,4-pentanedionato-O,O) (1) and dimer [FPt]2 (2) were explored within the density functional theory ...The structural, electronic and spectroscopic properties of monomer FPt (2-(4′,6′-difluorophenyl)pyridinato-N,C2′)(2,4-pentanedionato-O,O) (1) and dimer [FPt]2 (2) were explored within the density functional theory (DFT) and time-dependent DFT (TD-DFT). The calculated geometry parameters and spectroscopic results agree well with the experimental observation. In the ground state, FPt exists in the form of monomer, while in the excited state, dimer [FPt]2 forms with a Pt-Pt contraction of 0.05 nm due to the promotion of σ[dz2(Pt2)] to π*(phenylryridyl) and σ[pz(Pt2)]. Transition properties of monomer and excimer are different in nature: the former originates from mixed transitions of 3MLCT and 3ILCT, while the latter is dominated by 3MMLCT transition.展开更多
Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp...Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp drop of resistivity at about T SDW=119K.This anomaly is associated with the possible spin density wave(SDW)order.Interestingly near T SDW,the resistivity exhibits a cusp-like feature,which may be understood as the strong coupling effect between the electrons and the antiferromagnetic(AF)spin fluctuations.A reduction of fluorine or application of a high pressure will suppress the SDW feature and induce superconductivity.Hall effect measurements reveal a positive Hall coefficient below T SDW indicating a dominant role of the hole-like charge carriers in the parent phase.Strong magnetoresistance has been observed below T SDW suggesting multiple conduction channels of the charge carriers.展开更多
文摘The protonation effects on one- and two-photon absorption properties of an octupolar molecule TA with 1,3,5-triazine core and pyrrole electron-donating end-groups have been studied at hybrid density functional theory level. A computational scheme is developed to simulate a proton attached to an atom. The numerical results show that large changes in both one- and two-photon absorption properties are observed when the compound is transformed from neutral to threefold protonated states. When the compound is protonated, more charge transfer states appear and the absorption band has a red-shift. Furthermore, the two-photon absorption cross-section is largely enhanced. The theoretical calculations demonstrate the protonation effect on promoting the intramolecular charge transfer strength. The results present qualitative agreement with the experimental observations. A two-photon absorption switch with the compound TA based on the protonation effect is proposed.
基金supported by the"Strategic Priority Research Program(B)"of the Chinese Academy of Sciences(Grant No.XDB05020205)the National Natural Science Foundation of China(Grant No.41405131)the China Postdoctoral Science Foundation(Grant No.2014M550442)
文摘Single particle mass spectrometry has been widely used to determine the size and chemical compositions of at- mospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this study, two methods were developed for determining aerosol effective density by a single particle aerosol mass spectrometer （SPAMS）. Method I retrieved effective density through comparison between measured light scattering intensities and Mie theoretical modelled par- tial scattering cross section. Method Ⅱ coupled a differential mobility analyzer （DMA） with SPAMS to simultaneously deter- mine the electric mobility and vacuum aerodynamic diameter, and thus the effective density. Polystyrene latex spheres, ammo- nium sulfate and sodium nitrate were tested by these methods to help validate their effectiveness for determining the aerosol effective density. This study effectively extends SPAMS measurements to include particle size, chemical composition, light scattering, and effective density, and thus helps us better understand the environment and climate effects of aerosols.
基金Supported by National Natural Science Foundation of China under Grant No.11547177
文摘Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.
基金supported by the National Natural Science Foundation of China(Grant No.11534005)the Ministry of Science and Technology of China(Grant Nos.2011CBA00102 and 2012CB821403)
文摘The recently discovered(Li_(1-x) Fe_x)OHFe Se superconductor with T c about 40 K provides a good platform for investigating the magnetization and electrical transport properties of Fe Se-based superconductors. By using a hydrothermal ion-exchange method,we have successfully grown crystals of(Li_(1-x) Fe_x)OHFe Se. X-ray diffraction on the sample shows the single crystalline Pb O-type structure with the c-axis preferential orientation. Magnetic susceptibility and resistive measurements show an onset superconducting transition at around T c=38.3 K. Using the magnetization hysteresis loops and Bean critical state model, a large critical current J s is observed in low temperature region. The critical current density is suppressed exponentially with increasing magnetic field.Temperature dependencies of resistivity under various currents and fields are measured, revealing a robust superconducting current density and bulk superconductivity.
基金supported by the Research Fund for the Doctoral Program of Higher Education of China (200801831004)the Fundamental Research Funds for the Central Universities (HIT.NSRIF.2009083)+1 种基金the National Natural Science Foundation of China (20703015)the Program for New Century Excellent Talents of Common Universities of Heilongjiang Province (1154-NCET-010)
文摘The structural, electronic and spectroscopic properties of monomer FPt (2-(4′,6′-difluorophenyl)pyridinato-N,C2′)(2,4-pentanedionato-O,O) (1) and dimer [FPt]2 (2) were explored within the density functional theory (DFT) and time-dependent DFT (TD-DFT). The calculated geometry parameters and spectroscopic results agree well with the experimental observation. In the ground state, FPt exists in the form of monomer, while in the excited state, dimer [FPt]2 forms with a Pt-Pt contraction of 0.05 nm due to the promotion of σ[dz2(Pt2)] to π*(phenylryridyl) and σ[pz(Pt2)]. Transition properties of monomer and excimer are different in nature: the former originates from mixed transitions of 3MLCT and 3ILCT, while the latter is dominated by 3MMLCT transition.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00102,2010CB923002 and 2012CB821403)the National Natural Science Foundation of China and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Using self-flux method,we have successfully grown the parent phase of the single crystals of CaFeAsF1-x.The X-ray di?raction indicates good crystallinity.In-plane resistivity shows a bad metallic behavior with a sharp drop of resistivity at about T SDW=119K.This anomaly is associated with the possible spin density wave(SDW)order.Interestingly near T SDW,the resistivity exhibits a cusp-like feature,which may be understood as the strong coupling effect between the electrons and the antiferromagnetic(AF)spin fluctuations.A reduction of fluorine or application of a high pressure will suppress the SDW feature and induce superconductivity.Hall effect measurements reveal a positive Hall coefficient below T SDW indicating a dominant role of the hole-like charge carriers in the parent phase.Strong magnetoresistance has been observed below T SDW suggesting multiple conduction channels of the charge carriers.
