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Helicity of harmonic generation and attosecond polarization with bichromatic circularly polarized laser fields

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Chinese physics B 2019年第10期28卷 321-326页

作者： Jun Zhang Tong Qi Xue-Fei pan Jing Guo Kai-Guang Zhu Xue-Shen Liu College of Instrumentation and Electrical Engineering Jilin UniversityChangchun 130026China institute of atomic and molecular physics Jilin UniversityChangchun 130012China

We theoretically investigate the high-order harmonic generation(HHG) of helium atom driven by bichromatic counterrotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fields, the spectral chirality of the HHG can be controlled. As the intensity ratio increases, the spectral chirality will change from positive-to negativevalue around a large intensity ratio of the two driving fields when the total laser intensity keeps unchanged. However, the sign of the spectral chirality can be changed from positive to negative around a small intensity ratio of the two driving fields when the total laser intensity changes. At this time, we can effectively control the helicity of the harmonic spectrum and the polarization of the resulting attosecond pulses by adjusting the intensity ratio of the two driving laser fields. As the intensity ratio and the total intensity of the driving laser fields increase, the relative intensity of either the left-circularly or right-circularly polarized harmonic can be enhanced. The attosecond pulses can evolve from being elliptical to near linear correspondingly.

关键词： high-order harmonic generation bichromatic circularly polarized laser fields spectral chirality attosecond polarization

Ultrafast Coulomb explosion imaging of molecules and molecular clusters

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Chinese physics B 2022年第10期31卷 8-22页

作者： Xiaokai Li Xitao Yu pan Ma Xinning Zhao Chuncheng Wang Sizuo Luo Dajun Ding institute of atomic and molecular physics Jilin UniversityChangchun 130012China

Taking an image of their structure and a movie of their dynamics of small quantum systems have always been a dream of physicists and chemists. Laser-induced Coulomb explosion imaging(CEI) provides a great opportunity to make this dream a reality for small molecules or their aggregation — clusters. The method is unique for identifying the atomic locations with angstrom spatial resolution and capturing the structural evolution with a femtosecond time scale, in particular for imaging transient state products. This review summarizes the determination of three-dimensional equilibrium geometry of molecules and molecular cluster system through the reconstruction from the fragments momenta, and also shows that the dissociation dynamics on the complex potential energy surface can be tracked in real-time with the ultrafast CEI(UCEI).Furthermore, the detailed measurement and analysis procedures of the CEI, theoretical methods, exemplary results, and future perspectives of the technique are described.

关键词： Coulomb explosion imaging molecular structure molecular cluster ultrafast dissociation dynamics

Effect of elliptical polarizations on nonsequential double ionization in two-color elliptically polarized laser fields

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Chinese physics B 2018年第9期27卷 247-253页

作者： Tong-Tong Xu Jia-He Chen Xue-Fei pan Hong-Dan Zhang Shuai Ben and Xue-Shen Liu t institute of atomic and molecular physics Jilin UniversityChangchun 130012China

Using the classical ensemble model, we investigate the nonsequential double ionization（NSDI） of Ar and Mg in the two-color elliptically polarized laser pulse for different elliptical polarizations. Numerical results show that for Ar atoms the NSDI yield increases as the ellipticity increases, which is different from the case of Mg atoms. Moreover, the correlated behavior in the correlated electron momentum along the x direction and ion momentum distributions of Ar atoms are influenced by the ellipticity. By statistical analysis of different times, we can conclude that the ellipticity may be responsible for the NSDI processes. The correlated momenta distributions along the x direction at the recollision time are demonstrated and the results show that the travelling time and ellipticity can affect the emitted directions of both electrons.

关键词： nonsequential double ionization two-color elliptically polarized laser pulse ellipticity momentum distributions

Variability of Multiphoton Detachment Rate Versus Laser Intensity

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Chinese physics Letters 1996年第5期13卷 355-358页

作者： WANG Bing-bing ZHU Qi-ren pan Shou-fu institute of atomic and molecular physics Jilin University.Changchun 130023

With the help of a model calculation based on the R-matrix-Floquet theory,the variability of multiphoton detachment rate versus laser intensity is in detail investigated.A number of interesting regularities,which can ... 详细信息

关键词： perturbation theory lowest

Two-center interference in high-harmonic generation of H2%＋ in a combination of a mid-infrared laser field and a terahertz field

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Chinese physics B 2017年第1期26卷 176-181页

作者： Jun Zhang Xue-Fei pan Tong-Tong Xu Hong-Dan Zhang Hui Du Jing Guo Xue-Shen Liu institute of atomic and molecular physics Jilin University Changchun 130012 China

We theoretically investigate the two-center interference in high-order harmonics generated from the H2-＋ in a combination of a mid-infrared laser and a terahertz field by numerically solving the time-dependent Schr ¨odinger equation（TDSE）.The interference minima in high-order harmonic generation（HHG） are effectively suppressed when a THz field is *** contribution to HHG from the two separate nuclei is used to demonstrate the locating order of the harmonic ***, we also investigate the emission time of harmonics. The results show that the intensity of the short path around 60^th order after adding a THz field is stronger than that in the mid-infrared laser field, which further illustrates the suppression of the interference minima in HHG.

关键词： terahertz field high-order harmonic two-center interference

Multiphoton Ionization of Potassium Atoms in Femtosecond Laser Fields

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Chinese physics Letters 2021年第5期38卷 27-30页

作者： Wankai Li Yue Lei Xing Li Tao Yang Mei Du Ying Jiang Jialong Li Sizuo Luo Aihua Liu Lanhai He pan Ma Dongdong Zhang Dajun Ding institute of atomic and molecular physics Jilin UniversityChangchun 130012China

We study the multiphoton ionization of potassium atoms in 800 nm and 400 nm femtosecond laser *** the 800 nm laser field,the potassium atom absorbs three photons and emits one electron via one photon resonance with the 4p intermediate state with the help of the ac-Stark *** resonance feature is clearly shown as an Autler-Townes(AT) splitting and is mapped out in the electron kinetic energy *** a 400 nm laser field,although one photon resonance is possible with the 5p state,no splitting is *** different transition amplitudes between 4s-4p and 4s-5p explain the observed *** to the AT effect,an unexpected peak in the photoelectron energy spectrum that violates the dipole transition rule is observed.A preliminary explanation involving the spin-orbit interaction in the p state is given to account for this *** observed ATsplitting in the electron kinetic energy distribution can be used as an effective method to calibrate the intensity of a laser field.

关键词： net Multiphoton Ionization of Potassium Atoms in Femtosecond Laser Fields

Spatial distribution on high-order-harmonic generation of an H2+ molecule in intense laser fields

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Spatial distribution on high-order-harmonic generation of an...

Spectral shift of solid high-order harmonics from different channels in a combined laser field

第六届全国计算原子与分子物理学术会议

作者： Jun Zhang Hong-Dan Zhang Xue-Fei pan Tong-Tong Xu Jing Guo Xue-Shen Liu institute of atomic and molecular physics Jilin University

＜正＞High-order-harmonic generation（HHG）via laser-matter interaction has been intensively studied in recent years because of its applications in generating isolated attosecond *** attosecond pulses are significant for probing,for example,nuclear dynamics and photoelectron wave *** the molecular structure is more complex and the degrees of freedom in molecules are more than that in atoms,the harmonic

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Chinese physics B 2023年第3期32卷 244-251页

作者：曹冬冬潘雪飞张军刘学深 institute of atomic and molecular physics Jilin UniversityChangchun 130012China College of Science Northeast Forestry UniversityHarbin 150040China

We investigate theoretically the spectral shift of the high-order harmonic generation(HHG)in ZnO driven by a combined laser field by solving the two-band semiconductor Bloch equations(SBEs)in the velocity *** combined laser field is synthesized by a fundamental laser pulse and its seventh-frequency laser *** the seventh-frequency laser pulse is added to the rising or falling parts of the fundamental laser field,we find that the spectral blueshift or redshift appears,which is due to the unequal contribution of the rising and falling parts in the fundamental laser field to the *** analyzing the time-dependent conduction band population in k space,we found that,in addition to the tunneling ionization channel,there is also the resonant electron injection channels which is induced by the seventh-frequency laser *** harmonics generated by the different channels show the spectral redshift or the spectral blueshift,*** analyzing the k-integrated transient conduction band population of the electrons from different channels,we found that if there is a certain delay in the process of the electron excitation,it will lead to the delay in the harmonic emission,which results in the spectral redshift of the harmonics.

关键词： high-order harmonic generation ZnO crystal spectral shift of harmonics resonant electron injection channels