The crystalline materials Ca3Sc2Si3O12 and Ca3Y2Si3O12 Were characterized by different crystal structures, as the fonmer is a cubic garnet, while the latter is an orthorhombic compound. We investigated the optical spe...The crystalline materials Ca3Sc2Si3O12 and Ca3Y2Si3O12 Were characterized by different crystal structures, as the fonmer is a cubic garnet, while the latter is an orthorhombic compound. We investigated the optical spectroscopy of these materials doped with several trivalent lanthanide ions and compared the results for the two hosts. PolycrystaUine samples were prepared by solid state reaction, both undoped and doped with the trivalent lanthanide ions Eu3＋, Tb3＋ and Sm3＋. Emission, excitation and Raman spectra of these materials were measured at temperatures ranging from 300 to 10 K. The optical spectra were assigned and discussed, and the effects of the crystal structure of the host on the spectroscopic behaviour were addressed. The technological potential of these compounds in the field of optical materials and devices was discussed,展开更多
Novel approaches for high contrast, deep tissue, in vivo fluorescence biomedical imaging are based on infrared-emitting nanoparticles working in the so-called second biological window （1,000-1,400 nm）. This allows f...Novel approaches for high contrast, deep tissue, in vivo fluorescence biomedical imaging are based on infrared-emitting nanoparticles working in the so-called second biological window （1,000-1,400 nm）. This allows for the acquisition of high resolution, deep tissue images due to the partial transparency of tissues in this particular spectral range. In addition, the optical excitation with low energy （infrared） photons also leads to a drastic reduction in the contribution of autofluorescence to the in vivo image. Nevertheless, as is demonstrated here, working solely in this biological window does not ensure a complete removal of autofluorescence as the specimens diet shows a remarkable infrared fluorescence that extends up to 1,100 nm. In this work, we show how the 1,340 nm emission band of Nd3. ions embedded in SrF2 nanoparticles can be used to produce autofluorescence free, high contrast in vivo fluorescence images. It is also dem- onstrated that the complete removal of the food-related infrared autofluorescence is imperative for the development of reliable biodistribution studies.展开更多
The whitlockite-like crystal structure of Ca9Lu（PO4）7 when doped with several ions （Yb3＋, EU3＋ and Pr3＋） at different concentrations （1 tool.%, 5 mol.% and 10 tool.%） was studied, by means of synchrotron X-ra...The whitlockite-like crystal structure of Ca9Lu（PO4）7 when doped with several ions （Yb3＋, EU3＋ and Pr3＋） at different concentrations （1 tool.%, 5 mol.% and 10 tool.%） was studied, by means of synchrotron X-ray diffraction. In particular for Eu3＋ and Pr3＋, the presence of the dopant ion significantly changed the occupation factors （OFs） of the Ca2＋ and Lu3＋ cations and gave rise to a distortion of the metal-oxygen polyhedra. The observed structural features clearly showed significant impact of the dopant ion on the crystal structure of the host.展开更多
The Eu(Ⅲ)nitrate complex of the meso-N,N’-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligand was synthesized and characterized by single crystal and powder X-ray diffraction.The crystal lattice of the compl...The Eu(Ⅲ)nitrate complex of the meso-N,N’-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligand was synthesized and characterized by single crystal and powder X-ray diffraction.The crystal lattice of the complex is capable of absorbing and desorbing selectively acetonitrile molecules,at 293 K upon an acetonitrile vapor pressure of^0.1×10^5 Pa.This process,which is partially reversible,can be easily followed by both powder X-ray diffraction(P-XRD)and Eu(III)luminescence spectroscopy.The acetonitrile molecule,located in the outer coordination sphere of the metal ion,does not affect the radiative transition probability of 5 D0 level of Eu(Ⅲ)and also it does not activate further non-radiative channels from this level.On the other hand,this molecule is capable of affecting the energy position and intensities of the crystal field components of the 5 D0→7 F2 transition.The complex in solid form can be considered a promising material for the optical sensing of acetonitrile vapors.展开更多
文摘The crystalline materials Ca3Sc2Si3O12 and Ca3Y2Si3O12 Were characterized by different crystal structures, as the fonmer is a cubic garnet, while the latter is an orthorhombic compound. We investigated the optical spectroscopy of these materials doped with several trivalent lanthanide ions and compared the results for the two hosts. PolycrystaUine samples were prepared by solid state reaction, both undoped and doped with the trivalent lanthanide ions Eu3＋, Tb3＋ and Sm3＋. Emission, excitation and Raman spectra of these materials were measured at temperatures ranging from 300 to 10 K. The optical spectra were assigned and discussed, and the effects of the crystal structure of the host on the spectroscopic behaviour were addressed. The technological potential of these compounds in the field of optical materials and devices was discussed,
文摘Novel approaches for high contrast, deep tissue, in vivo fluorescence biomedical imaging are based on infrared-emitting nanoparticles working in the so-called second biological window （1,000-1,400 nm）. This allows for the acquisition of high resolution, deep tissue images due to the partial transparency of tissues in this particular spectral range. In addition, the optical excitation with low energy （infrared） photons also leads to a drastic reduction in the contribution of autofluorescence to the in vivo image. Nevertheless, as is demonstrated here, working solely in this biological window does not ensure a complete removal of autofluorescence as the specimens diet shows a remarkable infrared fluorescence that extends up to 1,100 nm. In this work, we show how the 1,340 nm emission band of Nd3. ions embedded in SrF2 nanoparticles can be used to produce autofluorescence free, high contrast in vivo fluorescence images. It is also dem- onstrated that the complete removal of the food-related infrared autofluorescence is imperative for the development of reliable biodistribution studies.
文摘The whitlockite-like crystal structure of Ca9Lu（PO4）7 when doped with several ions （Yb3＋, EU3＋ and Pr3＋） at different concentrations （1 tool.%, 5 mol.% and 10 tool.%） was studied, by means of synchrotron X-ray diffraction. In particular for Eu3＋ and Pr3＋, the presence of the dopant ion significantly changed the occupation factors （OFs） of the Ca2＋ and Lu3＋ cations and gave rise to a distortion of the metal-oxygen polyhedra. The observed structural features clearly showed significant impact of the dopant ion on the crystal structure of the host.
文摘The Eu(Ⅲ)nitrate complex of the meso-N,N’-bis(2-pyridylmethylene)-1,2-(R,S)-cyclohexanediamine ligand was synthesized and characterized by single crystal and powder X-ray diffraction.The crystal lattice of the complex is capable of absorbing and desorbing selectively acetonitrile molecules,at 293 K upon an acetonitrile vapor pressure of^0.1×10^5 Pa.This process,which is partially reversible,can be easily followed by both powder X-ray diffraction(P-XRD)and Eu(III)luminescence spectroscopy.The acetonitrile molecule,located in the outer coordination sphere of the metal ion,does not affect the radiative transition probability of 5 D0 level of Eu(Ⅲ)and also it does not activate further non-radiative channels from this level.On the other hand,this molecule is capable of affecting the energy position and intensities of the crystal field components of the 5 D0→7 F2 transition.The complex in solid form can be considered a promising material for the optical sensing of acetonitrile vapors.
