The formation and qualification of redox sites in transition metal oxides are always the active fields related to electronics, catalysis, sensors, and energy-storage units. In the present study, the temperature depend...The formation and qualification of redox sites in transition metal oxides are always the active fields related to electronics, catalysis, sensors, and energy-storage units. In the present study, the temperature dependence of thermal reduction of MoO3 was surveyed at the range of 350℃ to 750℃. Upon reduction, the formed redox species characterized by EPR spectroscopy are the MoVion and superoxide anion radical (O2-) when the reduction was induced at the optimal temperature of 300-350℃. When heating-up from 350℃, the EPR signals started to decline in amplitude. The signals in the range of 400-450℃ decreased to half of that at 350℃, and then to zero at ~600℃. Further treatment at even higher temperature or prolonged heating time at 500℃ caused more reduction and more free electrons were released to the MoO3 bulk, which results in a delocalized means similar to the antiferromagnetic coupling. These data herein are helpful to prepare and study the metal-oxide catalysts.展开更多
Since novel optoelectronic devices based on the peculiar behaviors of the tunneling probability, e.g., resonant tunneling devices (RTD) and band-pass filter, are steadily proposed, the analytic transfer matrix (ATM) m...Since novel optoelectronic devices based on the peculiar behaviors of the tunneling probability, e.g., resonant tunneling devices (RTD) and band-pass filter, are steadily proposed, the analytic transfer matrix (ATM) method is extended to study these devices. For several examples, we explore the effect of the scattered subwaves on tunneling; it is shown that the resonant or band-pass structures in tunneling probability are determined by the phase shift results from the scattered subwaves.展开更多
Electron Paramagnetic Resonance(EPR)is the only spectral method for direct detection of paramagnetic substances.EPR technology can be used for the qualitative and quantitative analysis of free radicals and transition ...Electron Paramagnetic Resonance(EPR)is the only spectral method for direct detection of paramagnetic substances.EPR technology can be used for the qualitative and quantitative analysis of free radicals and transition metals in solid,liquid,gas,cell and living samples.It is widely used in chemistry,material science,life science,quantum physics and other researches.This report discusses the basic principle,instrument structure,common problem solving,daily maintenance,and management model of the electron paramagnetic resonance spectrometer(German Bruker A-200)in the State Key Laboratory of Natural and Biomimetic Drugs of Peking University Health Science Center,so that the instrument can be fully used for various scientific researches.展开更多
基金supported by the National Key R&D Program of China(No.2018YFA0306600)AnHui Initiative in Quantum Information Technologies(No.AHY050000)
文摘The formation and qualification of redox sites in transition metal oxides are always the active fields related to electronics, catalysis, sensors, and energy-storage units. In the present study, the temperature dependence of thermal reduction of MoO3 was surveyed at the range of 350℃ to 750℃. Upon reduction, the formed redox species characterized by EPR spectroscopy are the MoVion and superoxide anion radical (O2-) when the reduction was induced at the optimal temperature of 300-350℃. When heating-up from 350℃, the EPR signals started to decline in amplitude. The signals in the range of 400-450℃ decreased to half of that at 350℃, and then to zero at ~600℃. Further treatment at even higher temperature or prolonged heating time at 500℃ caused more reduction and more free electrons were released to the MoO3 bulk, which results in a delocalized means similar to the antiferromagnetic coupling. These data herein are helpful to prepare and study the metal-oxide catalysts.
基金supported by the State Key Laboratory of Advanced Optical Communication Systems and Networks (Grant No. 2008SH05)
文摘Since novel optoelectronic devices based on the peculiar behaviors of the tunneling probability, e.g., resonant tunneling devices (RTD) and band-pass filter, are steadily proposed, the analytic transfer matrix (ATM) method is extended to study these devices. For several examples, we explore the effect of the scattered subwaves on tunneling; it is shown that the resonant or band-pass structures in tunneling probability are determined by the phase shift results from the scattered subwaves.
文摘Electron Paramagnetic Resonance(EPR)is the only spectral method for direct detection of paramagnetic substances.EPR technology can be used for the qualitative and quantitative analysis of free radicals and transition metals in solid,liquid,gas,cell and living samples.It is widely used in chemistry,material science,life science,quantum physics and other researches.This report discusses the basic principle,instrument structure,common problem solving,daily maintenance,and management model of the electron paramagnetic resonance spectrometer(German Bruker A-200)in the State Key Laboratory of Natural and Biomimetic Drugs of Peking University Health Science Center,so that the instrument can be fully used for various scientific researches.