We report a newly constructed laser ablation crossed molecular beam apparatus, equipped with time-sliced velocity map imaging technique, to study state-to-state metal atom reaction dynamics. Supersonic metal atomic be...We report a newly constructed laser ablation crossed molecular beam apparatus, equipped with time-sliced velocity map imaging technique, to study state-to-state metal atom reaction dynamics. Supersonic metal atomic beam is generated by laser vaporization of metal rod, and free expansion design without gas flow channel has been employed to obtain a good quality of metal atomic beam. We have chosen the crossed-beam reaction Al＋O2 to test the performance of the new apparatus. Two-rotational-states selected AIO（X^2∑＋, v=0, N and N＋I4） products can be imaged via P（N） and R（N＋14） branches of the Av=l band at the same wavelength, during （1＋1） resonance-enhanced multi-photon ionization through the AIO（D2E＋） intermediate state. In our experiment at 244.145 nm for simultaneous transitions of P（15） and R（29） branch, two rings in slice image were clearly distinguishable, corresponding to the AiO（v=0, N=IS） and AIO（v=0, N=29） states respectively. The energy difference between the two rotational levels is 403 cm^-1. The success of two states resolved in our apparatus suggests a better collisional energy resolution compared with the recent research study [J. Chem. Phys. 140, 214304 （2014）].展开更多
The interaction potentials between electron and atom play an important role in electron- atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born ap...The interaction potentials between electron and atom play an important role in electron- atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born approximation theory. Results show that these model potentials are successful in the laser-assisted e-Ar scattering system. The influence of static potential, exchange potential and polarization potential on the absolute differential cross section is also analyzed and discussed.展开更多
The reaction dynamics of yttrium atoms with sulfur dioxide molecules at a high collision energy of 36 kcal/mol was studied using time-sliced velocity map ion imaging,crossed molecular beam and laser-ablation method.Th...The reaction dynamics of yttrium atoms with sulfur dioxide molecules at a high collision energy of 36 kcal/mol was studied using time-sliced velocity map ion imaging,crossed molecular beam and laser-ablation method.The product YO was detected via multiphoton ionization at various wavelengths in the region of 482-615 nm.The slice images of YO show a broad velocity distribution and forward-backward peaking angular distribution.The forward scattering signal is stronger than its backward distribution.This indicates that the reaction proceeds via an intermediate complex and the lifetime of the intermediate state is less than one rotational period.The formation of complex suggests that electron transfer occurs in the oxidation reaction.展开更多
One of the themes of modern molecular reac tion dynamics is to charac terize elementary chemical reactions from“quan tum state to quan tum stat e”,and the study of molecular reaction dynamics in excited states can h...One of the themes of modern molecular reac tion dynamics is to charac terize elementary chemical reactions from“quan tum state to quan tum stat e”,and the study of molecular reaction dynamics in excited states can help test the validi ty of modern chemical t heories and provide met hods to cont rol chemical reactions.The subject of this review is to describe the recent experimental techniques used to study the reaction dynamics of metal atoms in the gas phase.Through these techniques,information such as the internal energy distribution and angular distribution of the nascent products or the three-dimensional stereodynamic reactivity can be obtained.In addition,by preparing metal at oms wi th specific exci ted elec tronic states or orbi tal arrangemen ts,information about the reactivity of the electronic states enriches the relevant understanding of the electron transfer mechanism in metal reaction dynamics.展开更多
It is shown that,in an open ladder-type atomic system with spontaneously generated coherence (SGC),regardless of the existence of an incoherent pumping,a lasing without inversion (LWI) gain is always remarkable larger...It is shown that,in an open ladder-type atomic system with spontaneously generated coherence (SGC),regardless of the existence of an incoherent pumping,a lasing without inversion (LWI) gain is always remarkable larger than in the system without SGC,by adjusting the strength of SGC.Moreover,LWI gain in the system without incoherent pumping is much larger than that with incoherent pumping,within some strength of SGC; while in the corresponding closed system with SGC,we can’t obtain LWI gain at any strength of SGC,if no incoherent pumping is applied.展开更多
We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connect...We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connection with the internal system parameters.展开更多
A scheme for one-step preparation of atomic GHZ states in two directly coupled cavities via virtual excitations is proposed.In the whole procedure,the information is carried only in two ground states of A-type atoms, ...A scheme for one-step preparation of atomic GHZ states in two directly coupled cavities via virtual excitations is proposed.In the whole procedure,the information is carried only in two ground states of A-type atoms, while the excited states of atoms and cavity modes are virtually excited,leading the system to be insensitive to atomic spontaneous emission and photon loss.展开更多
We analyze the dynamics of a bright soliton in atomic scattering length in an expulsive parabolic potential. Bose-Einstein condensates （BECs） with time-dependent Under a safe ravage of parameters in which the Gross...We analyze the dynamics of a bright soliton in atomic scattering length in an expulsive parabolic potential. Bose-Einstein condensates （BECs） with time-dependent Under a safe ravage of parameters in which the Gross-Pitaevskii （GP） equation is effective in one dimension, our results show that, the dynamics of the bright soliton can be classed into two phases, depending on the value of the scattering length. Meanwhile, there exists a critical value of the absolute value of the atomic scattering length, below which, the dynamics of the bright soliton is very regular. Those phenomena can be useful for developing concrete applications of the nonlinear matter waves. We also obtain the orbital equation of the bright soliton and get some interesting data which may be useful for the experimental observation of the bright soliton and the application of the atom laser with manipulated intensity.展开更多
Relativistic mean-field theory and phase-shift analysis are combined together to investigate the elasticCoulomb scattering between electrons and unstable nuclei.Electron scattering at several different energies is stu...Relativistic mean-field theory and phase-shift analysis are combined together to investigate the elasticCoulomb scattering between electrons and unstable nuclei.Electron scattering at several different energies is studiedand compared,in order to see the energy dependence of electron-nucleus scattering.It is shown that electron scattering at200 MeV or 300 MeV can be used to reveal electron-nucleus scattering information around the first diffraction minimum-Shiftsin opposite directions are obtained for the first diffraction minima of the electron scattering off the ground andfirst excited states of ^(17)F with ^(16)O as reference,and similar effects are obtained for ^(18)Ne.Besides,some neutron-richN = 8 isotones are also studied.Results show that electron scattering will be very useful and important in studyingboth proton- and neutron-rich nuclei in the future.展开更多
The spontaneous emission of an excited atom embedded in photonic crystals with two atomic position-dependent bands is investigated.The distribution of the density of states between two bands depends on the atomic posi...The spontaneous emission of an excited atom embedded in photonic crystals with two atomic position-dependent bands is investigated.The distribution of the density of states between two bands depends on the atomic position in a unit cell of the photonic crystal and is described with an atomic position-dependent parameter.The result shows that the emitted field and the time evolution of the upper-level population are affected by the atomic position and the gap width.The spontaneous emission spectrum in free space can be shifted and narrowed with the photonic reservoir and the gap width.展开更多
In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state ...In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state with a single-photon emitted have to be far smaller than 1 to obtain an acceptable entangled state.Based on strong dipole-dipole interaction between two Rydberg atoms,two simultaneous excitations in an atomic ensemble are greatly suppressed,which makes it possible to excite a mesoscopic cold atomic ensemble into a near-ideal singly-excited symmetric collective state accompanied by a signal-photon with near unity success probability.展开更多
基金We are indebted to Prof. Kopin Liu （IAMS, Taipei） for stimulating discussions on going experiments, to Prof. Ming-fei Zhou and Assoc. Prof. Guan-jun Wang （Fudan University, Shanghai） for assistance in building machine, to Prof. Uzi. Even （Tel Aviv University, Tel Aviv） for discussions oil E1 valve employnmnt in laser ablation, and to Prof. Xue-ming Yang＇s group （DICP, Dalian） for new Iaser system. This work was supported by the National Natural Science Foundation of China （No.21322309） and the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning.
文摘We report a newly constructed laser ablation crossed molecular beam apparatus, equipped with time-sliced velocity map imaging technique, to study state-to-state metal atom reaction dynamics. Supersonic metal atomic beam is generated by laser vaporization of metal rod, and free expansion design without gas flow channel has been employed to obtain a good quality of metal atomic beam. We have chosen the crossed-beam reaction Al＋O2 to test the performance of the new apparatus. Two-rotational-states selected AIO（X^2∑＋, v=0, N and N＋I4） products can be imaged via P（N） and R（N＋14） branches of the Av=l band at the same wavelength, during （1＋1） resonance-enhanced multi-photon ionization through the AIO（D2E＋） intermediate state. In our experiment at 244.145 nm for simultaneous transitions of P（15） and R（29） branch, two rings in slice image were clearly distinguishable, corresponding to the AiO（v=0, N=IS） and AIO（v=0, N=29） states respectively. The energy difference between the two rotational levels is 403 cm^-1. The success of two states resolved in our apparatus suggests a better collisional energy resolution compared with the recent research study [J. Chem. Phys. 140, 214304 （2014）].
文摘The interaction potentials between electron and atom play an important role in electron- atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born approximation theory. Results show that these model potentials are successful in the laser-assisted e-Ar scattering system. The influence of static potential, exchange potential and polarization potential on the absolute differential cross section is also analyzed and discussed.
基金supported by the National Natural Science Foundation of China (No.21673047,No.21327901and No.21573047)the Shanghai Key Laboratory Foundation of Molecular Catalysis and Innovative Materialsthe Program for Professor of Special Appointment(Eastern Scholar) at Shanghai Institutions of Higher Learning.
文摘The reaction dynamics of yttrium atoms with sulfur dioxide molecules at a high collision energy of 36 kcal/mol was studied using time-sliced velocity map ion imaging,crossed molecular beam and laser-ablation method.The product YO was detected via multiphoton ionization at various wavelengths in the region of 482-615 nm.The slice images of YO show a broad velocity distribution and forward-backward peaking angular distribution.The forward scattering signal is stronger than its backward distribution.This indicates that the reaction proceeds via an intermediate complex and the lifetime of the intermediate state is less than one rotational period.The formation of complex suggests that electron transfer occurs in the oxidation reaction.
基金The work was supported by the National Natural Science Foundation of China(No.21673047 and No.22073019)the Shanghai Key Laboratory Foundation of Molecular Catalysis and Innovative Materialsthe Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.
文摘One of the themes of modern molecular reac tion dynamics is to charac terize elementary chemical reactions from“quan tum state to quan tum stat e”,and the study of molecular reaction dynamics in excited states can help test the validi ty of modern chemical t heories and provide met hods to cont rol chemical reactions.The subject of this review is to describe the recent experimental techniques used to study the reaction dynamics of metal atoms in the gas phase.Through these techniques,information such as the internal energy distribution and angular distribution of the nascent products or the three-dimensional stereodynamic reactivity can be obtained.In addition,by preparing metal at oms wi th specific exci ted elec tronic states or orbi tal arrangemen ts,information about the reactivity of the electronic states enriches the relevant understanding of the electron transfer mechanism in metal reaction dynamics.
文摘It is shown that,in an open ladder-type atomic system with spontaneously generated coherence (SGC),regardless of the existence of an incoherent pumping,a lasing without inversion (LWI) gain is always remarkable larger than in the system without SGC,by adjusting the strength of SGC.Moreover,LWI gain in the system without incoherent pumping is much larger than that with incoherent pumping,within some strength of SGC; while in the corresponding closed system with SGC,we can’t obtain LWI gain at any strength of SGC,if no incoherent pumping is applied.
文摘We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connection with the internal system parameters.
基金Supported in part by the Natural Science Foundation of China under Grant Nos.10974125,60821004,60878059in part by the Educational Committee of Fujian Province under Grant No.JA09041in part by Fujian Normal University under Grant No.2008100220
文摘A scheme for one-step preparation of atomic GHZ states in two directly coupled cavities via virtual excitations is proposed.In the whole procedure,the information is carried only in two ground states of A-type atoms, while the excited states of atoms and cavity modes are virtually excited,leading the system to be insensitive to atomic spontaneous emission and photon loss.
基金Supported by National Natural Science Foundation of China under Grant Nos.90406017 and 60525417the NKBRSF of China under Grant No.2006CB921400
文摘We analyze the dynamics of a bright soliton in atomic scattering length in an expulsive parabolic potential. Bose-Einstein condensates （BECs） with time-dependent Under a safe ravage of parameters in which the Gross-Pitaevskii （GP） equation is effective in one dimension, our results show that, the dynamics of the bright soliton can be classed into two phases, depending on the value of the scattering length. Meanwhile, there exists a critical value of the absolute value of the atomic scattering length, below which, the dynamics of the bright soliton is very regular. Those phenomena can be useful for developing concrete applications of the nonlinear matter waves. We also obtain the orbital equation of the bright soliton and get some interesting data which may be useful for the experimental observation of the bright soliton and the application of the atom laser with manipulated intensity.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10535010,10675090,10775068,and 10975072the 973 National Major State Basic Research and Development of China under Grant No.2007CB815004+1 种基金CAS Knowledge Innovation Project KJCX2-SW-N02the Research Fund of Doctoral Point (RFDP) under Grant No.20070284016
文摘Relativistic mean-field theory and phase-shift analysis are combined together to investigate the elasticCoulomb scattering between electrons and unstable nuclei.Electron scattering at several different energies is studiedand compared,in order to see the energy dependence of electron-nucleus scattering.It is shown that electron scattering at200 MeV or 300 MeV can be used to reveal electron-nucleus scattering information around the first diffraction minimum-Shiftsin opposite directions are obtained for the first diffraction minima of the electron scattering off the ground andfirst excited states of ^(17)F with ^(16)O as reference,and similar effects are obtained for ^(18)Ne.Besides,some neutron-richN = 8 isotones are also studied.Results show that electron scattering will be very useful and important in studyingboth proton- and neutron-rich nuclei in the future.
基金supported by the Natural Science College Key Projects of Anhui Province (Grant Nos. KJ2010A335 and KJ2012Z023)the National Natural Science Foundation of China (Grant Nos. 41075027 and 61205115)the Key Project of Chinese Ministry of Education (Grant No. 212076)
文摘The spontaneous emission of an excited atom embedded in photonic crystals with two atomic position-dependent bands is investigated.The distribution of the density of states between two bands depends on the atomic position in a unit cell of the photonic crystal and is described with an atomic position-dependent parameter.The result shows that the emitted field and the time evolution of the upper-level population are affected by the atomic position and the gap width.The spontaneous emission spectrum in free space can be shifted and narrowed with the photonic reservoir and the gap width.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 61076094,11072218,and 11272287Zhejiang Provincial Natural Science Foundation of China under Grant No. Y6110314Scientific Research Fund of Zhejiang Provincial Education Department under Grant No. Y200909693
文摘In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state with a single-photon emitted have to be far smaller than 1 to obtain an acceptable entangled state.Based on strong dipole-dipole interaction between two Rydberg atoms,two simultaneous excitations in an atomic ensemble are greatly suppressed,which makes it possible to excite a mesoscopic cold atomic ensemble into a near-ideal singly-excited symmetric collective state accompanied by a signal-photon with near unity success probability.
