Molecular-frame photoelectron momentum distributions(MF-PMDs) of an H_(2)^(+) molecule ion in the presence of a pair of counter-rotating circularly polarized attosecond extreme ultraviolet laser pulses is studied by n...Molecular-frame photoelectron momentum distributions(MF-PMDs) of an H_(2)^(+) molecule ion in the presence of a pair of counter-rotating circularly polarized attosecond extreme ultraviolet laser pulses is studied by numerically solving the two-dimensional time-dependent Schrodinger equation within the frozen-nuclei approximation. At small time delay, our simulations show that the electron vortex structure is sensitive to the time delay and relative phase between the counterrotating pulses when they are partially overlapped. By adjusting time delay and relative phase, we have the ability to manipulate the MF-PMDs and the appearance of spiral arms. We further show that the internuclear distance can affect the spiral vortices due to its different transition cross sections in the parallel and perpendicular geometries. The lowest-order perturbation theory is employed to interpret these phenomena qualitatively. It is concluded that the internuclear distancedependent transition cross sections and the confinement effect in diatomic molecules are responsible for the variation of vortex structures in the MF-PMDs.展开更多
The low energy scattering of electrons by sodium at incident energies up to ionization threshold are calculated by applying the momentum space coupled-channel-optical （CCO） method. The present results are in good ag...The low energy scattering of electrons by sodium at incident energies up to ionization threshold are calculated by applying the momentum space coupled-channel-optical （CCO） method. The present results are in good agreement with the previous experimental and theoretical results. Furthermore, three resonances in the total cross sections observed by previous experiments are proved by the present calculation.展开更多
We perform a theoretical study on dynamic interference in single photon ionization of ground state hydrogen atoms in the presence of a super-intense ultra-fast chirped laser pulse of different chirp types(equal-power ...We perform a theoretical study on dynamic interference in single photon ionization of ground state hydrogen atoms in the presence of a super-intense ultra-fast chirped laser pulse of different chirp types(equal-power and equal-FWHM laser pulses)by numerically solving the time-dependent Schrödinger equation in one dimension.We investigate the influences of peak intensity and chirp parameters on the instantaneous ionization rate and photoelectron yield,respectively.We also compare the photoelectron energy spectra for the ionization by the laser pulses with different chirp types.We find that the difference between the instantaneous ionization rates for the ionization of hydrogen atom driven by two different chirped laser pulses is originated from the difference in variation of vector potentials with time.展开更多
We have investigated the electron scattering from the freely movable spin-1/2 particle in the presence of a linearly polarized laser field in the first Born approximation.The laser-dressed state of electrons is descri...We have investigated the electron scattering from the freely movable spin-1/2 particle in the presence of a linearly polarized laser field in the first Born approximation.The laser-dressed state of electrons is described by a time-dependent wave function which is derived from a perturbation treatment.With the aids of numerical simulations, we explore the dependencies of the differential cross section on the laser field intensity as well as the electron-impact energy.Due to the mobility of the target, the differential cross section of this process is smaller than that of Mott scattering.展开更多
The standard distorted wave Born approximation （DWBA） method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target. Second-order...The standard distorted wave Born approximation （DWBA） method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target. Second-order DWBA calculations have been preformed to investigate the triple differential cross sections （TDCS） of coplanar doubly symmetric （e, 2e） collisions for the alkali target potassium at excess energies of 6 eV-60 eV. Compared with the previous first-order DWBA calculations, the present theoretical model improves the degree of agreement with experiments, especially for the backward scattering angle region of TDCS. This indicates that the present second-order Born term is capable of giving a reasonable correction to the DWBA model in studying coplanar symmetric （e, 2e） problems in low and intermediate energy ranges.展开更多
Positronium （Ps） formation for positron impact on metastable hydrogen in 2s state has been studied by using the two- channel, two-center eikonal final state-continuum initial distorted wave （EFS-CDW） method. The d...Positronium （Ps） formation for positron impact on metastable hydrogen in 2s state has been studied by using the two- channel, two-center eikonal final state-continuum initial distorted wave （EFS-CDW） method. The differential, integrated, and total cross sections for Ps formation in different states have been calculated from each channel opening thresholds to high energy region. The results are compared with other theoretical calculations available in the literature. For Ps formation in s-state at intermediate and high energies, our results are in good agreement with the prediction of distorted wave theory. Those formed in p-states and the total Ps formation cross sections are reported for the first time. It is shown that the total Ps formation cross sections for positron scattering from H（2s） state are significantly larger at relatively low energies, while smaller at high energies, compared with those obtained from hydrogen in ground state.展开更多
The momentum-space coupled-channels-optical （CCO） method is used to study the resonances in electron oxygen collision in the energy region of 9-12 eV, Present results have shown agreement with the available experime...The momentum-space coupled-channels-optical （CCO） method is used to study the resonances in electron oxygen collision in the energy region of 9-12 eV, Present results have shown agreement with the available experimental and theoretical results, and new positions of resonances are found by the comparison of total cross sections,展开更多
The direct ionization cross sections for electron scattering by nitrogen are calculated by applying an equivalentlocal optical model from 15eV to 1100eV. The present results are compared with the experimental data and...The direct ionization cross sections for electron scattering by nitrogen are calculated by applying an equivalentlocal optical model from 15eV to 1100eV. The present results are compared with the experimental data and other theoretical calculation results.展开更多
An application of the coupled-channels optical method is given for the energy-dependent phenomena of positron- hydrogen resonances below the n = 2 excitation threshold. The equivalent local optical potential is used t...An application of the coupled-channels optical method is given for the energy-dependent phenomena of positron- hydrogen resonances below the n = 2 excitation threshold. The equivalent local optical potential is used to account for the target polarization and positronium formation. The calculation includes 9 explicitly physical coupled channels. The lowest S-wave resonance energy position and new resonances are found. Angular dependence of the cross section in the resonance region are investigated.展开更多
We investigate high partial wave resonances in positron-hydrogen scattering using the momentum-space coupledchannels optical method above the H (n =2) threshold.Resonances with angular momenta of L =0-6 are reported.I...We investigate high partial wave resonances in positron-hydrogen scattering using the momentum-space coupledchannels optical method above the H (n =2) threshold.Resonances with angular momenta of L =0-6 are reported.Ionization continuum and positronium formation channels are included via a complex equivalent local potential.Comparisons with the existing theoretical results are presented.展开更多
We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical（CCO） method for incident energies below the H ionization thre...We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical（CCO） method for incident energies below the H ionization threshold. The target continuum and the positronium（Ps） formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed.展开更多
基金Project supported by the Natural Science Foundation of Jilin Province,China (Grant No.20220101016JC)the National Key Research and Development Program of China (Grant No.2022YFE0134200)+1 种基金the National Natural Science Foundation of China (Grant Nos.12174147,91850114,and 11774131)the Open Research Fund of State Key Laboratory of Transient Optics and Photonics。
文摘Molecular-frame photoelectron momentum distributions(MF-PMDs) of an H_(2)^(+) molecule ion in the presence of a pair of counter-rotating circularly polarized attosecond extreme ultraviolet laser pulses is studied by numerically solving the two-dimensional time-dependent Schrodinger equation within the frozen-nuclei approximation. At small time delay, our simulations show that the electron vortex structure is sensitive to the time delay and relative phase between the counterrotating pulses when they are partially overlapped. By adjusting time delay and relative phase, we have the ability to manipulate the MF-PMDs and the appearance of spiral arms. We further show that the internuclear distance can affect the spiral vortices due to its different transition cross sections in the parallel and perpendicular geometries. The lowest-order perturbation theory is employed to interpret these phenomena qualitatively. It is concluded that the internuclear distancedependent transition cross sections and the confinement effect in diatomic molecules are responsible for the variation of vortex structures in the MF-PMDs.
文摘The low energy scattering of electrons by sodium at incident energies up to ionization threshold are calculated by applying the momentum space coupled-channel-optical （CCO） method. The present results are in good agreement with the previous experimental and theoretical results. Furthermore, three resonances in the total cross sections observed by previous experiments are proved by the present calculation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774131 and 91850114).
文摘We perform a theoretical study on dynamic interference in single photon ionization of ground state hydrogen atoms in the presence of a super-intense ultra-fast chirped laser pulse of different chirp types(equal-power and equal-FWHM laser pulses)by numerically solving the time-dependent Schrödinger equation in one dimension.We investigate the influences of peak intensity and chirp parameters on the instantaneous ionization rate and photoelectron yield,respectively.We also compare the photoelectron energy spectra for the ionization by the laser pulses with different chirp types.We find that the difference between the instantaneous ionization rates for the ionization of hydrogen atom driven by two different chirped laser pulses is originated from the difference in variation of vector potentials with time.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774131,91850114,11604119,and 11627807)
文摘We have investigated the electron scattering from the freely movable spin-1/2 particle in the presence of a linearly polarized laser field in the first Born approximation.The laser-dressed state of electrons is described by a time-dependent wave function which is derived from a perturbation treatment.With the aids of numerical simulations, we explore the dependencies of the differential cross section on the laser field intensity as well as the electron-impact energy.Due to the mobility of the target, the differential cross section of this process is smaller than that of Mott scattering.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11174066)
文摘The standard distorted wave Born approximation （DWBA） method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target. Second-order DWBA calculations have been preformed to investigate the triple differential cross sections （TDCS） of coplanar doubly symmetric （e, 2e） collisions for the alkali target potassium at excess energies of 6 eV-60 eV. Compared with the previous first-order DWBA calculations, the present theoretical model improves the degree of agreement with experiments, especially for the backward scattering angle region of TDCS. This indicates that the present second-order Born term is capable of giving a reasonable correction to the DWBA model in studying coplanar symmetric （e, 2e） problems in low and intermediate energy ranges.
基金Project supported by the National Natural Science Foundation of China(Grant No.11504128)
文摘Positronium （Ps） formation for positron impact on metastable hydrogen in 2s state has been studied by using the two- channel, two-center eikonal final state-continuum initial distorted wave （EFS-CDW） method. The differential, integrated, and total cross sections for Ps formation in different states have been calculated from each channel opening thresholds to high energy region. The results are compared with other theoretical calculations available in the literature. For Ps formation in s-state at intermediate and high energies, our results are in good agreement with the prediction of distorted wave theory. Those formed in p-states and the total Ps formation cross sections are reported for the first time. It is shown that the total Ps formation cross sections for positron scattering from H（2s） state are significantly larger at relatively low energies, while smaller at high energies, compared with those obtained from hydrogen in ground state.
文摘The momentum-space coupled-channels-optical （CCO） method is used to study the resonances in electron oxygen collision in the energy region of 9-12 eV, Present results have shown agreement with the available experimental and theoretical results, and new positions of resonances are found by the comparison of total cross sections,
文摘The direct ionization cross sections for electron scattering by nitrogen are calculated by applying an equivalentlocal optical model from 15eV to 1100eV. The present results are compared with the experimental data and other theoretical calculation results.
基金Project supported by the National Natural Science Foundation of China(Grant No.10674055)
文摘An application of the coupled-channels optical method is given for the energy-dependent phenomena of positron- hydrogen resonances below the n = 2 excitation threshold. The equivalent local optical potential is used to account for the target polarization and positronium formation. The calculation includes 9 explicitly physical coupled channels. The lowest S-wave resonance energy position and new resonances are found. Angular dependence of the cross section in the resonance region are investigated.
基金Supported by the National Natural Science Foundation of China under Grant No 10674055.
文摘We investigate high partial wave resonances in positron-hydrogen scattering using the momentum-space coupledchannels optical method above the H (n =2) threshold.Resonances with angular momenta of L =0-6 are reported.Ionization continuum and positronium formation channels are included via a complex equivalent local potential.Comparisons with the existing theoretical results are presented.
基金Project supported by the Nanyang Normal University Science Foundation of China(Grant No.ZX2013017)the National Natural Science Foundation of China(Grant Nos.11174066,61306007,and U1304114)
文摘We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical（CCO） method for incident energies below the H ionization threshold. The target continuum and the positronium（Ps） formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed.
