Nanopowder of Cr：GGG and nanopowder of Cr,Nd：GGG with different concentrations of Cr3＋ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravime...Nanopowder of Cr：GGG and nanopowder of Cr,Nd：GGG with different concentrations of Cr3＋ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravimetric analysis and differential scanning calorimetry （TGA-DSC）, X-ray diffraction （XRD） and photoluminescence spectroscopy were used to characterize the powder. The crystallite size was about 58 nm when treated at 1000 oC for 2 h. Cr3＋ photoluminescence spectrum in GGG showed a broad band emission around 730 nm. The intensity of this band decreased when co-doped with Nd, indicating an efficient energy transfer from Cr3＋ to Nd3＋. Photoluminescence intensity of Nd in Cr,Nd：GGG at 1.06μm showed that the optimum concentration of Cr3＋ was about 1 at.% （more or less） for 1 at.% Nd3＋. This result was also confirmed by chromium fluorescence decay rate analysis. Energy transfer efficiency was found to be about 84% for 1 at.% concentration of each chromium and neodymium.展开更多
In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic exc...In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic excitation transfer to the reaction center(RC). In this decohering model, the Hamiltonian of the system commutes with the systemenvironment interaction. We take B850 ring of light-harvesting complex II(LH-II) in purple bacteria as an example to calculate the efficiency of the energy transfer as a function of time. We find that the environmental noise can make the LH-II have stable energy transfer efficiency over a long time. This is to say that the environmental noise which is the decohering source has advantage of the energy transfer in the process of photosynthesis.展开更多
文摘Nanopowder of Cr：GGG and nanopowder of Cr,Nd：GGG with different concentrations of Cr3＋ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravimetric analysis and differential scanning calorimetry （TGA-DSC）, X-ray diffraction （XRD） and photoluminescence spectroscopy were used to characterize the powder. The crystallite size was about 58 nm when treated at 1000 oC for 2 h. Cr3＋ photoluminescence spectrum in GGG showed a broad band emission around 730 nm. The intensity of this band decreased when co-doped with Nd, indicating an efficient energy transfer from Cr3＋ to Nd3＋. Photoluminescence intensity of Nd in Cr,Nd：GGG at 1.06μm showed that the optimum concentration of Cr3＋ was about 1 at.% （more or less） for 1 at.% Nd3＋. This result was also confirmed by chromium fluorescence decay rate analysis. Energy transfer efficiency was found to be about 84% for 1 at.% concentration of each chromium and neodymium.
基金Supported by the Research Start-up Foundation for Talents of Northwest A&F University of China under Grant Nos.Z111021106 and Z111021307
文摘In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic excitation transfer to the reaction center(RC). In this decohering model, the Hamiltonian of the system commutes with the systemenvironment interaction. We take B850 ring of light-harvesting complex II(LH-II) in purple bacteria as an example to calculate the efficiency of the energy transfer as a function of time. We find that the environmental noise can make the LH-II have stable energy transfer efficiency over a long time. This is to say that the environmental noise which is the decohering source has advantage of the energy transfer in the process of photosynthesis.
