Charge-transfer(CT) is an important enhancement mechanism in the field of surface-enhanced Raman scattering(SERS) that typically increases the Raman intensity of molecules by as much as 10–100 times.Herein, a low-cos...Charge-transfer(CT) is an important enhancement mechanism in the field of surface-enhanced Raman scattering(SERS) that typically increases the Raman intensity of molecules by as much as 10–100 times.Herein, a low-cost Ag_2O aggregates substrate was prepared via a facile chemical precipitation method,and the calculated CT-based enhancement factor of the uranyl ions adsorbed on it reached as high as 10~5, a metal-comparable value. The efficient photoinduced CT process from the valence band of Ag_2O to the LUMO of uranyl ions under appropriate excitation sources resulted in the repulsion of the axial oxygen atoms of the O=U=O bond, which enhanced its polarizability, creating a more intense Raman mode. To the best of our knowledge, this study firstly reports such a strong photoinduced CT enhancement of uranyl ions, with concentrations of 10^(-8) mol L^(-1) or lower being detected using this Ag_2O substrate. Most importantly, this research has shown that the photoinduced CT enhancement also contributes to the SERS of uranyl ions on pure Ag substrates which have often been ascribed to the electromagnetic enhancement in previous studies. In addition, Ag_2O can be used to selectively detect uranyl ions without interference from many other molecules or ions because of the energy matching rule of the photoinduced CT process, which was readily available for uranyl detection in the environmental aqueous solution.展开更多
Introduction Muon scattering tomography(MST)can be employed to scan cargo containers and vehicles for special nuclear materials by using cosmic muons.However,the flux of cosmic ray muons is relatively low for direct d...Introduction Muon scattering tomography(MST)can be employed to scan cargo containers and vehicles for special nuclear materials by using cosmic muons.However,the flux of cosmic ray muons is relatively low for direct detection.Thus,the detection has to be done in a short timescale with small numbers of muons to satisfy the demands of practical applications.Method In this paper,we propose an artificial neural network(ANN)algorithm for material discrimination using MST.The muon scattering angles were simulated using Geant4 to formulate the training set,and the muon scatter angles were measured by Micromegas detection system to create the test set.Results The ANN-based algorithm presented here ensures a discrimination accuracy of 98.0%between aluminum,copper and tungsten in a 5 min measurement of 4×4×4 cm^(3)blocks.展开更多
Sulfuric acid-treated poly（3,4-ethylenedioxythiophene）：poly（styrenesulfonate）/less-defective reduced graphene oxide （ST-PEDOT：PSS/L-rGO） composite films were prepared via a solution-processing route and used a...Sulfuric acid-treated poly（3,4-ethylenedioxythiophene）：poly（styrenesulfonate）/less-defective reduced graphene oxide （ST-PEDOT：PSS/L-rGO） composite films were prepared via a solution-processing route and used as the counter electrodes of dye sensitized solar cells （DSSCs）. These platinum （Pt）- and transparent conductive oxide （TCO）-free counter electrodes exhibited strong catalytic activity and excellent flexibility, showing no obvious change in their sheet resistances after 10000 cycles of bending. The integrated quasi-solid-state DSSC device with a TiO2 nanotube/Ti mesh photoanode and a ST-PEDOT：PSS/L-rGO counter electrode exhibited an energy conversion efficiency （~/） of about 1.8%. It also displayed an excellent mechanical stability and durability after bending for 1000 cycles at a small curvature radius of 10 mm. The high flexibility, low cost and efficient catalytic activity make ST-PEDOT：PSS/L-rGO composite films promising counter electrodes for flexible DSSCs.展开更多
基金supported by the Development Foundation of Radiochemistry(XK 909)of China Academy of Engineering Physics(CAEP)the National Natural Science Foundation of China(21501157,21504085)+2 种基金the Science Challenge Project(TZ2016000403)Sichuan Science and Technology Foundation for Young Scientists(2017JQ0050)Foundation for Special Talents in CAEP(TP201502-3)
文摘Charge-transfer(CT) is an important enhancement mechanism in the field of surface-enhanced Raman scattering(SERS) that typically increases the Raman intensity of molecules by as much as 10–100 times.Herein, a low-cost Ag_2O aggregates substrate was prepared via a facile chemical precipitation method,and the calculated CT-based enhancement factor of the uranyl ions adsorbed on it reached as high as 10~5, a metal-comparable value. The efficient photoinduced CT process from the valence band of Ag_2O to the LUMO of uranyl ions under appropriate excitation sources resulted in the repulsion of the axial oxygen atoms of the O=U=O bond, which enhanced its polarizability, creating a more intense Raman mode. To the best of our knowledge, this study firstly reports such a strong photoinduced CT enhancement of uranyl ions, with concentrations of 10^(-8) mol L^(-1) or lower being detected using this Ag_2O substrate. Most importantly, this research has shown that the photoinduced CT enhancement also contributes to the SERS of uranyl ions on pure Ag substrates which have often been ascribed to the electromagnetic enhancement in previous studies. In addition, Ag_2O can be used to selectively detect uranyl ions without interference from many other molecules or ions because of the energy matching rule of the photoinduced CT process, which was readily available for uranyl detection in the environmental aqueous solution.
基金supported by the Program of National Natural Science Foundation of China Grant Nos.11805168 and 21805251
文摘Introduction Muon scattering tomography(MST)can be employed to scan cargo containers and vehicles for special nuclear materials by using cosmic muons.However,the flux of cosmic ray muons is relatively low for direct detection.Thus,the detection has to be done in a short timescale with small numbers of muons to satisfy the demands of practical applications.Method In this paper,we propose an artificial neural network(ANN)algorithm for material discrimination using MST.The muon scattering angles were simulated using Geant4 to formulate the training set,and the muon scatter angles were measured by Micromegas detection system to create the test set.Results The ANN-based algorithm presented here ensures a discrimination accuracy of 98.0%between aluminum,copper and tungsten in a 5 min measurement of 4×4×4 cm^(3)blocks.
基金Acknowledgement This work was supported by the National Basic Research Program of China （973 Program, No. 2012CB933402） and the Natural Science Foundation of China （Nos. 51433005, 21274074）.
文摘Sulfuric acid-treated poly（3,4-ethylenedioxythiophene）：poly（styrenesulfonate）/less-defective reduced graphene oxide （ST-PEDOT：PSS/L-rGO） composite films were prepared via a solution-processing route and used as the counter electrodes of dye sensitized solar cells （DSSCs）. These platinum （Pt）- and transparent conductive oxide （TCO）-free counter electrodes exhibited strong catalytic activity and excellent flexibility, showing no obvious change in their sheet resistances after 10000 cycles of bending. The integrated quasi-solid-state DSSC device with a TiO2 nanotube/Ti mesh photoanode and a ST-PEDOT：PSS/L-rGO counter electrode exhibited an energy conversion efficiency （~/） of about 1.8%. It also displayed an excellent mechanical stability and durability after bending for 1000 cycles at a small curvature radius of 10 mm. The high flexibility, low cost and efficient catalytic activity make ST-PEDOT：PSS/L-rGO composite films promising counter electrodes for flexible DSSCs.
