The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational l...The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schrbdinger equation with the split- operator method. The calculation shows that the field parameters, such as intensity, wavelength, duration, and delay time etc. can have different influences on the vibrational population. By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state, which will benefit the light manipulation of atomic and molecular processes.展开更多
In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model m...In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model molecule A2B,Hydrogen ion H+2 and elementary atmospheric reaction N(4S)+O2(X 3Σ−g)→NO(X 2Π)+O(3P)calculated by means of Runge-Kutta methods and symplectic methods;the classical dissociation of the HF molecule and classical dynamics of H+2 in an intense laser field;the symplectic form and symplectic-scheme shooting method for the time-independent Schr¨odinger equation;the computation of continuum eigenfunction of the Schr¨odinger equation;asymptotic boundary conditions for solving the time-dependent Schr¨odinger equation of an atom in an intense laser field;symplectic discretization based on asymptotic boundary condition and the numerical eigenfunction expansion;and applications in computing multi-photon ionization,above-threshold ionization,Rabbi oscillation and high-order harmonic generation of laser-atom interaction.展开更多
Photodissociation of cyclopentanone (C5H8O) and cyclohexanone (C6H10O) was studied with 800nm, 50fs laser pulse at intensities of 5.0 - 13.0x10(13) W/cm(2). A time of flight mass spectrometer was employed to detect th...Photodissociation of cyclopentanone (C5H8O) and cyclohexanone (C6H10O) was studied with 800nm, 50fs laser pulse at intensities of 5.0 - 13.0x10(13) W/cm(2). A time of flight mass spectrometer was employed to detect the ion signals. Parent ions dominated at lower laser intensities. Fragmentation of the parent ions increases with increasing laser intensity and molecular size. The fragmentation mechanism was discussed.展开更多
Methanol was irradiated by 80 fs laser pulse, intensity range of 1013-1014 W/cm2. A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH3OH+ appeared firstly a...Methanol was irradiated by 80 fs laser pulse, intensity range of 1013-1014 W/cm2. A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH3OH+ appeared firstly at the laser intensity of 1.4 ×1013 W/cm2. While the laser intensity was gradually increased, the parent ions were dissociated and the primary ions CH2OH+ were given as verified from the irradiation of deuterated methanol (CH3OD) showing the C-H bond cracking firstly. While the laser intensity was further increased to 2.0 ×1013 W/cm2, the C-O bonds of the parent ions also broke to give CH3+. When the laser intensity was higher, smaller fragment ions like CH+, C+, OH+ and O+ also appeared. Among the fragment ions, only H+ ion yield had anisotropic angular distribution dependence on the laser polarization vector in the dissociation of methanol. All the experimental observations show that the dissociation of methanol proceeds through stepwise mechanism but not Coulomb explosion.展开更多
High-order harmonic generation(HHG) of Ar atom in an elliptically polarized intense laser field is experimentally investigated in this work.Interestingly,the anomalous ellipticity dependence on the laser ellipticity(...High-order harmonic generation(HHG) of Ar atom in an elliptically polarized intense laser field is experimentally investigated in this work.Interestingly,the anomalous ellipticity dependence on the laser ellipticity(ε) in the lower-order harmonics is observed,specifically in the 13rd-order,which displays a maximal harmonic intensity at ε ≈ 0.1,rather than at ε = 0 as expected.This contradicts the general trend of harmonic yield,which typically decreases with the increase of laser ellipticity.In this study,we attribute this phenomenon to the disruption of the symmetry of the wave function by the Coulomb effect,leading to the generation of a harmonic with high ellipticity.This finding provides valuable insights into the behavior of elliptically polarized harmonics and opens up a potential way for exploring new applications in ultrafast spectroscopy and light–matter interactions.展开更多
Comprehension of photon-triggered molecular processes is essential in the study of various important topics in physics,chemistry,and biology.Here we propose a correlated tunneling picture to understand the dissociativ...Comprehension of photon-triggered molecular processes is essential in the study of various important topics in physics,chemistry,and biology.Here we propose a correlated tunneling picture to understand the dissociative ionization process of molecules in intense laser fields based on a quantum model developed in the framework of many-body S-matrix theory including nuclear vibrational motion.In this quantum correlation picture,the single ionization of H_(2)and the subsequent electron-ion recollisioninduced dissociation are considered as an entangled correlated process.It enables us to attribute the interference pattern in the joint-energy spectra to combined effects of single-slit diffraction and multi-slit interference of correlated electron-nuclear wave packets in the time domain.Our work opens a new avenue to understanding molecular dissociative ionization processes in external fields.展开更多
Experimental results of high-order harmonic generation (HHG) in Ar and Ne gas driven with a 45fs Ti: sapphire laser are presented. The shortest-wavelength harmonic emission corresponding to the 91st order harmonic (8....Experimental results of high-order harmonic generation (HHG) in Ar and Ne gas driven with a 45fs Ti: sapphire laser are presented. The shortest-wavelength harmonic emission corresponding to the 91st order harmonic (8.63nm) is observed in argon. In neon, the harmonics up to order 131 (5.99nm) is also observed. The effects of gas density, laser intensity, free electron and the focusing geometry parameters of the laser beam on the process of harmonic generation are investigated. The direct experimental evidence that an increased electron density causes a degenerated harmonic radiation is obtained.展开更多
基金Project supported by the Natural Science Foundation of Shandong Province of China (Grant No. Y2006A23)the National Basic Research Program of China (Grant No. 2006CB806000)the Open Fund of the State Key Laboratory of High Field Laser Physics (Shanghai Institute of Optics and Fine Mechanics)
文摘The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schrbdinger equation with the split- operator method. The calculation shows that the field parameters, such as intensity, wavelength, duration, and delay time etc. can have different influences on the vibrational population. By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state, which will benefit the light manipulation of atomic and molecular processes.
基金supported in part by the National Natural Science Foundation of China(#10574057,#10571074,and#10171039)by the Specialized Research Fund for the Doctoral Program of Higher Education(#20050183010).
文摘In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model molecule A2B,Hydrogen ion H+2 and elementary atmospheric reaction N(4S)+O2(X 3Σ−g)→NO(X 2Π)+O(3P)calculated by means of Runge-Kutta methods and symplectic methods;the classical dissociation of the HF molecule and classical dynamics of H+2 in an intense laser field;the symplectic form and symplectic-scheme shooting method for the time-independent Schr¨odinger equation;the computation of continuum eigenfunction of the Schr¨odinger equation;asymptotic boundary conditions for solving the time-dependent Schr¨odinger equation of an atom in an intense laser field;symplectic discretization based on asymptotic boundary condition and the numerical eigenfunction expansion;and applications in computing multi-photon ionization,above-threshold ionization,Rabbi oscillation and high-order harmonic generation of laser-atom interaction.
文摘Photodissociation of cyclopentanone (C5H8O) and cyclohexanone (C6H10O) was studied with 800nm, 50fs laser pulse at intensities of 5.0 - 13.0x10(13) W/cm(2). A time of flight mass spectrometer was employed to detect the ion signals. Parent ions dominated at lower laser intensities. Fragmentation of the parent ions increases with increasing laser intensity and molecular size. The fragmentation mechanism was discussed.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 29973052) the Ministry of Science & Technology of China.
文摘Methanol was irradiated by 80 fs laser pulse, intensity range of 1013-1014 W/cm2. A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH3OH+ appeared firstly at the laser intensity of 1.4 ×1013 W/cm2. While the laser intensity was gradually increased, the parent ions were dissociated and the primary ions CH2OH+ were given as verified from the irradiation of deuterated methanol (CH3OD) showing the C-H bond cracking firstly. While the laser intensity was further increased to 2.0 ×1013 W/cm2, the C-O bonds of the parent ions also broke to give CH3+. When the laser intensity was higher, smaller fragment ions like CH+, C+, OH+ and O+ also appeared. Among the fragment ions, only H+ ion yield had anisotropic angular distribution dependence on the laser polarization vector in the dissociation of methanol. All the experimental observations show that the dissociation of methanol proceeds through stepwise mechanism but not Coulomb explosion.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92250306,11974137,and 12304302)the National Key Program for Science and Technology Research and Development of China(Grant No.2019YFA0307700)+1 种基金the Natural Science Foundation of Jilin Province,China(Grant Nos.YDZJ202101ZYTS157 and YDZJ202201ZYTS314)the Scientific Research Foundation of the Education Department of Jilin Province,China(Grant No.JJKH20230283KJ)。
文摘High-order harmonic generation(HHG) of Ar atom in an elliptically polarized intense laser field is experimentally investigated in this work.Interestingly,the anomalous ellipticity dependence on the laser ellipticity(ε) in the lower-order harmonics is observed,specifically in the 13rd-order,which displays a maximal harmonic intensity at ε ≈ 0.1,rather than at ε = 0 as expected.This contradicts the general trend of harmonic yield,which typically decreases with the increase of laser ellipticity.In this study,we attribute this phenomenon to the disruption of the symmetry of the wave function by the Coulomb effect,leading to the generation of a harmonic with high ellipticity.This finding provides valuable insights into the behavior of elliptically polarized harmonics and opens up a potential way for exploring new applications in ultrafast spectroscopy and light–matter interactions.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0307700)the National Natural Science Foundation of China(Grant Nos.12274273,12304379,11925405+2 种基金12304304)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302101)the Natural and Science Foundation of Top Talent of SZTU(Grant No.GDRC202202)。
文摘Comprehension of photon-triggered molecular processes is essential in the study of various important topics in physics,chemistry,and biology.Here we propose a correlated tunneling picture to understand the dissociative ionization process of molecules in intense laser fields based on a quantum model developed in the framework of many-body S-matrix theory including nuclear vibrational motion.In this quantum correlation picture,the single ionization of H_(2)and the subsequent electron-ion recollisioninduced dissociation are considered as an entangled correlated process.It enables us to attribute the interference pattern in the joint-energy spectra to combined effects of single-slit diffraction and multi-slit interference of correlated electron-nuclear wave packets in the time domain.Our work opens a new avenue to understanding molecular dissociative ionization processes in external fields.
基金Project supported by the Chinese Academy of Sciences and the High-Tech Project of China.
文摘Experimental results of high-order harmonic generation (HHG) in Ar and Ne gas driven with a 45fs Ti: sapphire laser are presented. The shortest-wavelength harmonic emission corresponding to the 91st order harmonic (8.63nm) is observed in argon. In neon, the harmonics up to order 131 (5.99nm) is also observed. The effects of gas density, laser intensity, free electron and the focusing geometry parameters of the laser beam on the process of harmonic generation are investigated. The direct experimental evidence that an increased electron density causes a degenerated harmonic radiation is obtained.
