The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phospho...The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phosphor were investigated usingX-ray diffraction (XRD) and a fluorescence spectrophotometer. The excitation spectrum exhibited a broad band between 230nm and 400 nm and the emission peaking at about 470 nm was observed, which originated from the allowed f-d transition ofEu2+ions at Ba2+sites. Owing to the different optimal concentrations under different excitation wavelengths (254 nm and 365nm), the energy-transfer mechanism in this phosphor has changed from the dipole-dipole interaction to the exchange interac-tion of Eu2+ions.展开更多
We report on a theoretical study of the π^-→α1（1260）p and π^-→π^-~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ^0 meson exchange.For t...We report on a theoretical study of the π^-→α1（1260）p and π^-→π^-~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ^0 meson exchange.For the π^-→π^-ρ~0p reaction,the final π^-p^0 results from the decay of the α1（1260） resonance,which is assumed as a dynamically generated state from the K＊ K and ρπ coupled channel interactions.We calculate the total cross section of the π^-→α1（1260）p reaction.It is shown that,with the coupling constant of the α1（1260） to ρπ channel obtained from the chiral unitary theory and a cut off parameter Δρ～1.5 GeV in the form factors,the experimental measurement can be reproduced.Furthermore,the total and differential cross sections of π^p→α1（1260）p→π^ρ^0p reaction are evaluated,and it is expected that our model calculations can be tested by future experiments.These reactions are important for the study of the α1（1260） resonance and would provide further constraints on the properties of the α1（1260） state.展开更多
基金supported by the Scientific and Technological Project of Chongqing, China (Grant No. CSTC, 2009AB4171)the Innovation Foundation for Technology Based Firms of Ministry of Science and Technology, China (Grant No. 04C26225100807)
文摘The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phosphor were investigated usingX-ray diffraction (XRD) and a fluorescence spectrophotometer. The excitation spectrum exhibited a broad band between 230nm and 400 nm and the emission peaking at about 470 nm was observed, which originated from the allowed f-d transition ofEu2+ions at Ba2+sites. Owing to the different optimal concentrations under different excitation wavelengths (254 nm and 365nm), the energy-transfer mechanism in this phosphor has changed from the dipole-dipole interaction to the exchange interac-tion of Eu2+ions.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11475227 and 11475015the Youth Innovation Promotion Association CAS under Grant No.2016367
文摘We report on a theoretical study of the π^-→α1（1260）p and π^-→π^-~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ^0 meson exchange.For the π^-→π^-ρ~0p reaction,the final π^-p^0 results from the decay of the α1（1260） resonance,which is assumed as a dynamically generated state from the K＊ K and ρπ coupled channel interactions.We calculate the total cross section of the π^-→α1（1260）p reaction.It is shown that,with the coupling constant of the α1（1260） to ρπ channel obtained from the chiral unitary theory and a cut off parameter Δρ～1.5 GeV in the form factors,the experimental measurement can be reproduced.Furthermore,the total and differential cross sections of π^p→α1（1260）p→π^ρ^0p reaction are evaluated,and it is expected that our model calculations can be tested by future experiments.These reactions are important for the study of the α1（1260） resonance and would provide further constraints on the properties of the α1（1260） state.
