We demonstrate the production of cold, slow NH_3 molecules from a supersonic NH_3 molecular beam using our electrostatic Stark decelerator consisting of 179 slowing stages. By using this long Stark decelerator, a supe...We demonstrate the production of cold, slow NH_3 molecules from a supersonic NH_3 molecular beam using our electrostatic Stark decelerator consisting of 179 slowing stages. By using this long Stark decelerator, a supersonic NH_3 molecular beam can be easily decelerated to trappable velocities. Here we present two modes for operating the Stark decelerator to slow the supersonic NH_3 molecules. The first is the normal mode, where all 179 stages are used to decelerate molecules, and it allows decelerating the NH_3 molecular beam from 333 m/s to 18 m/s, with a final temperature of 29.2 mK.The second is the deceleration-bunch mode, which allows us to decelerate the supersonic NH_3 beam from 333 m/s to 24 m/s,with a final temperature of 2.9 m K. It is clear that the second mode promises to produce colder(high-energy-resolution)molecular samples than the normal mode. Three-dimensional Monte Carlo simulations are also performed for the experiments and they show a good agreement with the observed results. The deceleration-bunch operation mode presented here can find applications in the fields of cold collisions, high-resolution spectroscopy, and precision measurements.展开更多
The metal—organic frameworks(MOFs)are expected as ideal biomimetic enzymes for colorimetric glucose detection because of their large surface areas,well defined pore structures,tunable chemical composition,and multi-f...The metal—organic frameworks(MOFs)are expected as ideal biomimetic enzymes for colorimetric glucose detection because of their large surface areas,well defined pore structures,tunable chemical composition,and multi-functional sites.However,the intrinsically chemical instability and low mimetic enzyme activity of MOFs hinder the application of them in imitating the enzyme reactions.In this work,we demonstrated a metal-MOF synergistic catalysis strategy,by loading Pt nanoparticles(Pt NPs)on MIL-88B-NH2(Fe-MOF)to increase peroxidase-like activity for the detection of glucose.The induced electrons transfer from Pt atom to Fe atom accelerated the redox cycling of Fe^(3+)/Fe^(2+),improved the overall efficiency of the peroxidase-like reaction,and enabled the efficient and robust colorimetric glucose detection,which was proved by both experiments and density functional theory(DFT)calculation.Additionally,the sensitivity and chemical stability of this synergistic effect strategy to detect the glucose are not affected by the complex external factors,which represented a great potential in fast,easy,sensitive,and specific recognition of clinical diabetes.展开更多
Strong-field-seeking states are the lowest-energy configurations for paramagnetic molecules in the magnetic field.Molecules in strong-field-seeking states cannot be trapped in a magnetostatic field because a magnetost...Strong-field-seeking states are the lowest-energy configurations for paramagnetic molecules in the magnetic field.Molecules in strong-field-seeking states cannot be trapped in a magnetostatic field because a magnetostatic maximum in free space is not allowed.In this paper,we propose an AC magnetic trap composed of two pairs of Helmholtz coils.The spatial magnetic field distribution is numerically calculated and the time-sequential control is depicted.We investigate the influence of the switching frequency and the electric current in the coils on the performance of our trap.Variations of the location and phase-space distribution during a whole switching cycle are simulated.Finally,we study the impact of time during which the field is switched off on the number of captured molecules in a switching cycle.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91536218,11034002,11274114,11504112,and 11504318)the National Basic Research Program of China(Grant No.2011CB921602)+1 种基金the Fundamental Research Funds for the Central Universities,China,Shanghai Pujiang Talents Plan,China(Grant No.18PJ1403100)Exploration Funds for the Shanghai Natural Science Foundation,China(Grant No.18ZR1412700)
文摘We demonstrate the production of cold, slow NH_3 molecules from a supersonic NH_3 molecular beam using our electrostatic Stark decelerator consisting of 179 slowing stages. By using this long Stark decelerator, a supersonic NH_3 molecular beam can be easily decelerated to trappable velocities. Here we present two modes for operating the Stark decelerator to slow the supersonic NH_3 molecules. The first is the normal mode, where all 179 stages are used to decelerate molecules, and it allows decelerating the NH_3 molecular beam from 333 m/s to 18 m/s, with a final temperature of 29.2 mK.The second is the deceleration-bunch mode, which allows us to decelerate the supersonic NH_3 beam from 333 m/s to 24 m/s,with a final temperature of 2.9 m K. It is clear that the second mode promises to produce colder(high-energy-resolution)molecular samples than the normal mode. Three-dimensional Monte Carlo simulations are also performed for the experiments and they show a good agreement with the observed results. The deceleration-bunch operation mode presented here can find applications in the fields of cold collisions, high-resolution spectroscopy, and precision measurements.
基金This work was supported by National Natural Science Foundation of China(Nos.21705117,21575115,21904095,and 22004089)Program of Tianjin Science and Technology Major Project and Engineering(No.19ZXYXSY00090)+3 种基金the Program for Chang Jiang Scholars and Innovative Research Team,Ministry of Education,China(No.IRT-16R61)Special Fund Project for the Central Government to Guide Local Science and Technology Development(2020)the Applied Fundamental Research Fund of Sichuan Province(No.2019YJ0169)the new scholar fund of UESTC.
文摘The metal—organic frameworks(MOFs)are expected as ideal biomimetic enzymes for colorimetric glucose detection because of their large surface areas,well defined pore structures,tunable chemical composition,and multi-functional sites.However,the intrinsically chemical instability and low mimetic enzyme activity of MOFs hinder the application of them in imitating the enzyme reactions.In this work,we demonstrated a metal-MOF synergistic catalysis strategy,by loading Pt nanoparticles(Pt NPs)on MIL-88B-NH2(Fe-MOF)to increase peroxidase-like activity for the detection of glucose.The induced electrons transfer from Pt atom to Fe atom accelerated the redox cycling of Fe^(3+)/Fe^(2+),improved the overall efficiency of the peroxidase-like reaction,and enabled the efficient and robust colorimetric glucose detection,which was proved by both experiments and density functional theory(DFT)calculation.Additionally,the sensitivity and chemical stability of this synergistic effect strategy to detect the glucose are not affected by the complex external factors,which represented a great potential in fast,easy,sensitive,and specific recognition of clinical diabetes.
基金supported by the National Natural Science Foundation of China(Grant No.11504318).
文摘Strong-field-seeking states are the lowest-energy configurations for paramagnetic molecules in the magnetic field.Molecules in strong-field-seeking states cannot be trapped in a magnetostatic field because a magnetostatic maximum in free space is not allowed.In this paper,we propose an AC magnetic trap composed of two pairs of Helmholtz coils.The spatial magnetic field distribution is numerically calculated and the time-sequential control is depicted.We investigate the influence of the switching frequency and the electric current in the coils on the performance of our trap.Variations of the location and phase-space distribution during a whole switching cycle are simulated.Finally,we study the impact of time during which the field is switched off on the number of captured molecules in a switching cycle.
