Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described ...Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.展开更多
This paper discusses the concept of controllable subspace for open quantum dynamical systems. It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perf...This paper discusses the concept of controllable subspace for open quantum dynamical systems. It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perform open-loop coherent control on open quantum systems will allow decoherence-free subspaces to be controllable. This is in contrast to the observation that open quantum dynamical systems are not open-loop controllable. To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subspaces can be useful for quantum computation.展开更多
Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taugh...Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taught advanced dynamics for more than ten years, this is the author＇s observation. Why it is so？ Because the course of advanced dynamics covers usually many mathematical fundamentals such as vectors, tensors, matrices and rotation operators; principles and applications in dynamics from particle dynamics to rigid body motion, from small oscillation to vibration of systems with multiple degrees of freedom, the author＇s course covers also special relativity theory. They are very innovative. And they set the foundation for the study of all the graduate courses. Science is always in progress, dynamics is in the same form. Just say a few examples to illustrate the frontier of dynamics： missile shooting missile is important in our defense, the author covered this as an example in particle dynamics. Space ship travels from Earth to Mars is another example. Several rotational motions with different axes can be combined to one through the use of rotation operator. This is important because it usually can save time. All these examples will be included in this paper in some details.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (NSFC Center for Chemical Dynamics (No.21688102)+4 种基金the National Natural Science Foundation of China (No.21673232, No.21873099, No.21922306)the International Partnership Program of Chinese Academy of Sci-ences (No.121421KYSB20170012)supported by the National Natural Science Foundation of China (No.21973010)supported by the National Natural Science Foundation of China (No.21773236)supported by the Natural Science Research Project of Education Department of Anhui Province (No.KJ2019A0521).
文摘Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.
基金The project supported by National Natural Science Foundation of China under Grant No.60674040National Natural Science Foundation for Distinguished Young Scholars under Grant No.60225015
文摘This paper discusses the concept of controllable subspace for open quantum dynamical systems. It is constructively demonstrated that combining structural features of decoherence-free subspaces with the ability to perform open-loop coherent control on open quantum systems will allow decoherence-free subspaces to be controllable. This is in contrast to the observation that open quantum dynamical systems are not open-loop controllable. To a certain extent, this paper gives an alternative control theoretical interpretation on why decoherence-free subspaces can be useful for quantum computation.
文摘Dynamics is the foundation of undergraduate study in mechanical engineering. If you are good in dynamics, you will be good on all other courses. Advanced dynamics is the foundation for graduate study. The author taught advanced dynamics for more than ten years, this is the author＇s observation. Why it is so？ Because the course of advanced dynamics covers usually many mathematical fundamentals such as vectors, tensors, matrices and rotation operators; principles and applications in dynamics from particle dynamics to rigid body motion, from small oscillation to vibration of systems with multiple degrees of freedom, the author＇s course covers also special relativity theory. They are very innovative. And they set the foundation for the study of all the graduate courses. Science is always in progress, dynamics is in the same form. Just say a few examples to illustrate the frontier of dynamics： missile shooting missile is important in our defense, the author covered this as an example in particle dynamics. Space ship travels from Earth to Mars is another example. Several rotational motions with different axes can be combined to one through the use of rotation operator. This is important because it usually can save time. All these examples will be included in this paper in some details.
