The alignment-dependent photoelectron spectrum is a valuable tool for mapping out the electronic structure of molecular orbitals.However,this approach may not be applicable to all molecules,such as CO_(2),as the ioniz...The alignment-dependent photoelectron spectrum is a valuable tool for mapping out the electronic structure of molecular orbitals.However,this approach may not be applicable to all molecules,such as CO_(2),as the ionization process in a linearly polarized laser field involves contributions from orbitals other than the highest occupied molecular orbital(HOMO).Here,we conducted a theoretical investigation into the ionization process of N_(2) and CO_(2) in near-circularly polarized laser field using the Coulomb-corrected strong-field approximation(CCSFA)method for molecules.In particular,we introduced a generalized dressed state into the CCSFA method in order to account for the impact of the laser field on the molecular initial state.The simulated alignment-dependent photoelectron momentum distribution(PMD)of the two molecules exhibited markedly disparate behaviors,which were in excellent agreement with the previous experimental observations reported in[Phys.Rev.A 102,013117(2020)].Our findings indicate that under a near-circularly polarized laser field,the alignment-dependent PMD of molecules is primarily sourced from the HOMO,in contrast to the situation under a linearly polarized laser field.Moreover,a satisfactory correlation between the alignment-dependent angular distribution and the orbital symmetry was observed,which suggests an effective approach for molecular orbital imaging.展开更多
The effect of initial longitudinal velocity of the tunnelled electron on the non-sequential double ionization （NSDI） process in an elliptically polarized laser field is studied by a semiclassical model. We find that...The effect of initial longitudinal velocity of the tunnelled electron on the non-sequential double ionization （NSDI） process in an elliptically polarized laser field is studied by a semiclassical model. We find that the non-zero initial longitudinal velocity has a suppressing effect on single-return collision （SRC） events in the double ionization process, more specifically, it results in an obvious reduction in the center part of the correlation momentum distributions in the direction of the major polarization axis （z axis） and makes the distribution of single-return collision in the minor polarization axis （x axis） become narrower.展开更多
The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic ap...The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic approximation in which the initial momentum of the electron is assumed to be zero. We theoretically study the nonadiabatic effect by assuming a nonzero initial momentum on the rescattering trajectories based on the semiclassical simpleman model. We show that the nonzero initial momentum will modify both the maximal return energy at collision and the final energy after backward scattering, but in different ways for odd and even number of return trajectories. The energies are increased for even number of returns but are decreased for odd number of returns when the nonzero （positive or negative） initial momentum is applied.展开更多
Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are ...Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.展开更多
With the development of attosecond science, tunneling time can now be measured experimentally with the attoclock technique. However, there are many different theoretical definitions of tunneling time and no consensus ...With the development of attosecond science, tunneling time can now be measured experimentally with the attoclock technique. However, there are many different theoretical definitions of tunneling time and no consensus has been achieved.Here, we bridge the relationship between different definitions of tunneling time based on a quantum travel time in onedimensional rectangular barrier tunneling problem. We find that the real quantum travel time t_(Re) is equal to the Bohmian time t_(Bohmian), which is related to the resonance lifetime of a bound state. The total quantum travel time τt can perfectly retrieve the transversal time t_x and the Büttiker–Landauer time τ_(BL) in two opposite limits, regardless of the particle energy.展开更多
Using a semiclassical model,we investigate the effect of the initial longitudinal velocity of the tunnel-ionized electron on low-energy structure(LES)in above-threshold ionization(ATI)spectra.Our analysis shows that t...Using a semiclassical model,we investigate the effect of the initial longitudinal velocity of the tunnel-ionized electron on low-energy structure(LES)in above-threshold ionization(ATI)spectra.Our analysis shows that the effect(reduction or enhancement)of the initial longitudinal velocity pz0 on the LES is dependent on the direction of the initial longitudinal velocity.For the initial longitudinal velocity along the direction of the laser electric field at the moment of tunneling(i.e.,pz0>0),the Coulomb interaction between the photoelectron and ion core is enhanced,while for the initial longitudinal velocity in the opposite direction(i.e.,pz0<0),the Coulomb effect is reduced.Our work provides solid evidence that the initial electron longitudinal velocity has considerable effect on the photoelectron dynamics in the ATI process.展开更多
The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is u...The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is used to quantitatively describe the electron-electron correlation. The dependence of α on elliptieity e is totally different in three directions. For the z direction （maJor polarization direction）, α first increases and reaches a maximum at ε = 0.275, then it decreases quickly. For the y direction in which the laser field is always absent, the ellipticity has a minor effect, and the asymmetry parameter fluctuates around α = -0.15. However, for the x direction （minor polarization direction）, α increases monotonously with ellipticity though starts from the same value as in the y direction when ε = 0. The behavior of α in the x direction actually indicates a transformation from the Coulomb interaction dominated correlation to the laser field dominated correlation. Therefore, our work provides an efficient way to control the three-dimensional electron electron correlation via an elliptically polarized intense laser field.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12274273).
文摘The alignment-dependent photoelectron spectrum is a valuable tool for mapping out the electronic structure of molecular orbitals.However,this approach may not be applicable to all molecules,such as CO_(2),as the ionization process in a linearly polarized laser field involves contributions from orbitals other than the highest occupied molecular orbital(HOMO).Here,we conducted a theoretical investigation into the ionization process of N_(2) and CO_(2) in near-circularly polarized laser field using the Coulomb-corrected strong-field approximation(CCSFA)method for molecules.In particular,we introduced a generalized dressed state into the CCSFA method in order to account for the impact of the laser field on the molecular initial state.The simulated alignment-dependent photoelectron momentum distribution(PMD)of the two molecules exhibited markedly disparate behaviors,which were in excellent agreement with the previous experimental observations reported in[Phys.Rev.A 102,013117(2020)].Our findings indicate that under a near-circularly polarized laser field,the alignment-dependent PMD of molecules is primarily sourced from the HOMO,in contrast to the situation under a linearly polarized laser field.Moreover,a satisfactory correlation between the alignment-dependent angular distribution and the orbital symmetry was observed,which suggests an effective approach for molecular orbital imaging.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11074026 and 11074155)the Program for New Century Excellent Talents in University of the Ministry of Education of China (Grant No. NCET-08-0883)
文摘The effect of initial longitudinal velocity of the tunnelled electron on the non-sequential double ionization （NSDI） process in an elliptically polarized laser field is studied by a semiclassical model. We find that the non-zero initial longitudinal velocity has a suppressing effect on single-return collision （SRC） events in the double ionization process, more specifically, it results in an obvious reduction in the center part of the correlation momentum distributions in the direction of the major polarization axis （z axis） and makes the distribution of single-return collision in the minor polarization axis （x axis） become narrower.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11425414 and 11504215the Scientific Research Training Program of Shanxi University
文摘The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic approximation in which the initial momentum of the electron is assumed to be zero. We theoretically study the nonadiabatic effect by assuming a nonzero initial momentum on the rescattering trajectories based on the semiclassical simpleman model. We show that the nonzero initial momentum will modify both the maximal return energy at collision and the final energy after backward scattering, but in different ways for odd and even number of return trajectories. The energies are increased for even number of returns but are decreased for odd number of returns when the nonzero （positive or negative） initial momentum is applied.
基金Project supported by the Key Laboratory Project of Computational Physics of National Defense Science and Technology of China(Grant No.6142A05180401)the National Key Program for S&T Research and Development of China(Grant Nos.2019YFA0307700 and 2016YFA0401100)the National Natural Science Foundation of China(Grant Nos.11847307,11425414,11504215,11774361,and 11874246).
文摘Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0401100)the National Natural Science Foundation of China(Grant Nos.11425414,11504215,and 11874246)
文摘With the development of attosecond science, tunneling time can now be measured experimentally with the attoclock technique. However, there are many different theoretical definitions of tunneling time and no consensus has been achieved.Here, we bridge the relationship between different definitions of tunneling time based on a quantum travel time in onedimensional rectangular barrier tunneling problem. We find that the real quantum travel time t_(Re) is equal to the Bohmian time t_(Bohmian), which is related to the resonance lifetime of a bound state. The total quantum travel time τt can perfectly retrieve the transversal time t_x and the Büttiker–Landauer time τ_(BL) in two opposite limits, regardless of the particle energy.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10925420,11074026,11174330 and 11274050the National Basic Research Program of China under Grant Nos 2013CB9222001 and 2011CB8081002。
文摘Using a semiclassical model,we investigate the effect of the initial longitudinal velocity of the tunnel-ionized electron on low-energy structure(LES)in above-threshold ionization(ATI)spectra.Our analysis shows that the effect(reduction or enhancement)of the initial longitudinal velocity pz0 on the LES is dependent on the direction of the initial longitudinal velocity.For the initial longitudinal velocity along the direction of the laser electric field at the moment of tunneling(i.e.,pz0>0),the Coulomb interaction between the photoelectron and ion core is enhanced,while for the initial longitudinal velocity in the opposite direction(i.e.,pz0<0),the Coulomb effect is reduced.Our work provides solid evidence that the initial electron longitudinal velocity has considerable effect on the photoelectron dynamics in the ATI process.
基金Supported by the National Key Program for S&T Research and Development under Grant No 2016YFA0401100the National Basic Research Program of China under Grant No 2013CB922201the National Natural Science Foundation of China under Grant Nos 11504215,11374197,11334009 and 11425414
文摘The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is used to quantitatively describe the electron-electron correlation. The dependence of α on elliptieity e is totally different in three directions. For the z direction （maJor polarization direction）, α first increases and reaches a maximum at ε = 0.275, then it decreases quickly. For the y direction in which the laser field is always absent, the ellipticity has a minor effect, and the asymmetry parameter fluctuates around α = -0.15. However, for the x direction （minor polarization direction）, α increases monotonously with ellipticity though starts from the same value as in the y direction when ε = 0. The behavior of α in the x direction actually indicates a transformation from the Coulomb interaction dominated correlation to the laser field dominated correlation. Therefore, our work provides an efficient way to control the three-dimensional electron electron correlation via an elliptically polarized intense laser field.
