In this paper, optical spectra of LiYF4 single crystals doped with Tm3＋ ions of various concentrations are reported. The emission intensity at 1.8 ktm first increases with increasing Tm3＋ concentration, and reaches ...In this paper, optical spectra of LiYF4 single crystals doped with Tm3＋ ions of various concentrations are reported. The emission intensity at 1.8 ktm first increases with increasing Tm3＋ concentration, and reaches a maximum value when the concentration of Tm3＋ is about 1.28 mol%, then it decreases rapidly as the concentration of Tm3＋ further increases to 3.49 mol%. The emission lifetime at 1.8 p.m also shows a similar tendency to the emission intensity. The maximum lifetime of 1.8 μm is measured to be 17.68 ms for the sample doped with Tm3＋ of 1.28 mol%. The emission cross section of 3F4 level is calculated. The maximum reaches 3.76 × 10 -21 cm2 at 1909 nm. The cross relaxation （3H6, 3H4 →3 F4, 3F4） between Tm3＋ ions and the concentration quenching effect are mainly attributed to the change of emission with Tm3＋ concentration. The largest quantum efficiency between Tm3＋ ions is estimated to be ,-147% from the measured lifetime and calculated radiative lifetime. All the results suggest that the Tm3＋/LiYF4 single crystal may have potential applications in 2 μm mid-infrared lasers.展开更多
[ Objective] The research aimed to study response rule of the M. aeruginosa fluorescence on the biological toxicity of HgCI2. [ Method ] M. aeruginosa as material, fluorescence intensity at its best excitation and emi...[ Objective] The research aimed to study response rule of the M. aeruginosa fluorescence on the biological toxicity of HgCI2. [ Method ] M. aeruginosa as material, fluorescence intensity at its best excitation and emission wavelengths as measured indicator, influence of the HgCI2 at different mass concentrations on fluorescence intensity of the M. aeruginosa was discussed initially. [ Result] HgCI2 at different mass concentrations had different influences on M. aeruginosa. HgCI2 at low concentration （0.002 -0.004 mg/L）could promote photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming smaller. 0.010 -0.400 mg/L of HgCI2 inhibited photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming bigger. Moreover, inhibition effect increased as HgCI2 concentration rose, showing a positive correlation between HgCI2 concentration and toxicity （ R 2 = 0.963 5 ）. [ Conclusion ] The research provided new theoretical basis for quickly measuring water toxicity.展开更多
The structure and catalytic properties of SrTi0.9M0.1O3- δ (M=Mg,Al, Zr) perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD),X ray photoelectron spectr...The structure and catalytic properties of SrTi0.9M0.1O3- δ (M=Mg,Al, Zr) perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD),X ray photoelectron spectroscopy (XPS) and temperature programmed desorption of oxygen(O2 TPD) methods. It has been shown that doping the cations of lower valence (e.g. Mg2+ , Al3+ ) to the B site of SrTi0.9M0.1O3- δ perovskite type catalysts results in the higher content of adsorbed oxygen species on the surface of catalysts and thus higher C2 selectivity for OCM reaction. It is suggested that the oxygen vacancies of SrTi0.9M0.1O3- δ (M=Mg, Al, Zr) perovskite type catalysts are the sites responsible for oxygen activation, and the adsorbed oxygen species on the surface of SrTi0.9M0.1O3- δ catalysts are the main active species for OCM reaction.展开更多
Reactions of Cd（OAC）2·2H2O with m-thioacetatebenzoic acid（H2L） and 1,10-phenanthroline（phen） give rise to a metal-organic framework,[CdL（phen）]n（1）.X-ray single-crystal diffraction reveals that 1 crysta...Reactions of Cd（OAC）2·2H2O with m-thioacetatebenzoic acid（H2L） and 1,10-phenanthroline（phen） give rise to a metal-organic framework,[CdL（phen）]n（1）.X-ray single-crystal diffraction reveals that 1 crystallizes in the monoclinic system,space group C2/c,with a= 25.7099（5）,b=10.3872（2）,c=19.1820（4）,β=131.114（1）°,V=3859.4（1）3,Mr=502.80,Z= 8,F（000）=2000,μ=1.271 mm-1,Dc=1.731 g·cm-3,the final R=0.0226 and wR=0.0559 for 3817 observed reflections（Ⅰ〉 2σ（Ⅰ））.1 displays a 1D double-strand chain structure with crab-like dinuclear subunits,and extends into a 3D network by π-π interactions and C-H···O hydrogen bonds.Photoluminescence studies reveal that it displays intense structure-related fluorescent emission bands（λex=342 nm） at 370.5 and 389 nm in the solid state at room temperature.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472125 and 51272109)the Natural Science Foundation of Ningbo City,China(Grant No.201401A6105016)K.C.Wong Magna Fund in Ningbo University,China(Grant No.NBUWC001)
文摘In this paper, optical spectra of LiYF4 single crystals doped with Tm3＋ ions of various concentrations are reported. The emission intensity at 1.8 ktm first increases with increasing Tm3＋ concentration, and reaches a maximum value when the concentration of Tm3＋ is about 1.28 mol%, then it decreases rapidly as the concentration of Tm3＋ further increases to 3.49 mol%. The emission lifetime at 1.8 p.m also shows a similar tendency to the emission intensity. The maximum lifetime of 1.8 μm is measured to be 17.68 ms for the sample doped with Tm3＋ of 1.28 mol%. The emission cross section of 3F4 level is calculated. The maximum reaches 3.76 × 10 -21 cm2 at 1909 nm. The cross relaxation （3H6, 3H4 →3 F4, 3F4） between Tm3＋ ions and the concentration quenching effect are mainly attributed to the change of emission with Tm3＋ concentration. The largest quantum efficiency between Tm3＋ ions is estimated to be ,-147% from the measured lifetime and calculated radiative lifetime. All the results suggest that the Tm3＋/LiYF4 single crystal may have potential applications in 2 μm mid-infrared lasers.
基金Supported by National 863 Item,China (2007AA092201)
文摘[ Objective] The research aimed to study response rule of the M. aeruginosa fluorescence on the biological toxicity of HgCI2. [ Method ] M. aeruginosa as material, fluorescence intensity at its best excitation and emission wavelengths as measured indicator, influence of the HgCI2 at different mass concentrations on fluorescence intensity of the M. aeruginosa was discussed initially. [ Result] HgCI2 at different mass concentrations had different influences on M. aeruginosa. HgCI2 at low concentration （0.002 -0.004 mg/L）could promote photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming smaller. 0.010 -0.400 mg/L of HgCI2 inhibited photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming bigger. Moreover, inhibition effect increased as HgCI2 concentration rose, showing a positive correlation between HgCI2 concentration and toxicity （ R 2 = 0.963 5 ）. [ Conclusion ] The research provided new theoretical basis for quickly measuring water toxicity.
文摘The structure and catalytic properties of SrTi0.9M0.1O3- δ (M=Mg,Al, Zr) perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD),X ray photoelectron spectroscopy (XPS) and temperature programmed desorption of oxygen(O2 TPD) methods. It has been shown that doping the cations of lower valence (e.g. Mg2+ , Al3+ ) to the B site of SrTi0.9M0.1O3- δ perovskite type catalysts results in the higher content of adsorbed oxygen species on the surface of catalysts and thus higher C2 selectivity for OCM reaction. It is suggested that the oxygen vacancies of SrTi0.9M0.1O3- δ (M=Mg, Al, Zr) perovskite type catalysts are the sites responsible for oxygen activation, and the adsorbed oxygen species on the surface of SrTi0.9M0.1O3- δ catalysts are the main active species for OCM reaction.
文摘Reactions of Cd（OAC）2·2H2O with m-thioacetatebenzoic acid（H2L） and 1,10-phenanthroline（phen） give rise to a metal-organic framework,[CdL（phen）]n（1）.X-ray single-crystal diffraction reveals that 1 crystallizes in the monoclinic system,space group C2/c,with a= 25.7099（5）,b=10.3872（2）,c=19.1820（4）,β=131.114（1）°,V=3859.4（1）3,Mr=502.80,Z= 8,F（000）=2000,μ=1.271 mm-1,Dc=1.731 g·cm-3,the final R=0.0226 and wR=0.0559 for 3817 observed reflections（Ⅰ〉 2σ（Ⅰ））.1 displays a 1D double-strand chain structure with crab-like dinuclear subunits,and extends into a 3D network by π-π interactions and C-H···O hydrogen bonds.Photoluminescence studies reveal that it displays intense structure-related fluorescent emission bands（λex=342 nm） at 370.5 and 389 nm in the solid state at room temperature.
