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Coherent emission and attosecond transient absorption of N_(2)^(+) in strong fields

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 2-7页

作者： Qian Zhang Guangru Bai Bin Zhang Jinlei Liu Hongbin Lei Xiaowei Wang Jing zhao zengxiu zhao Institute of Brain-Inspired Intelligence Nanjing UniversityNanjing 210093China School of Physics Nanjing University of Science and TechnologyNanjing 210094China

The ionic dynamics induced by strong-field ionization are essential to understand the fundamental physics and chemical *** solving the ionization-coupling equation theoretically,we can simultaneously address strong-field ionization and coupling dynamics in *** employing the driving pulse at the wavelength of 1580 nm,we show that the B^(2)Σ_(u)^(+) state of the strong field ionization created N_(2)^(+) could be populated by polarization effect and five-photon resonance but there is no population inversion between X^(2)Σ_(g)^(+) and B^(2)Σ_(u)^(+) states for the nitrogen molecular ions aligning along the laser *** addition,both the ultraviolet supercontinuum and the attosecond transient absorption spectroscopy(ATAS)are calculated to illustrate the characteristics of population and *** Stark shift observed from the transient absorption confirms the origin of ultraviolet *** results show the evolution of the absorption spectral lineshape,varying from Lorentzian to Fano to inverted Lorentzian and back forth and the optical gain is achieved at 394 e V due to the vibrational coherent *** study offers valuable insights into the strong-field quantum optics of molecular ions.

关键词： vibrational analysis ultraviolet spectra X-ray spectra

Real-Time Observation of Electron-Hole Coherence Induced by Strong-Field Ionization

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Chinese Physics Letters 2022年第12期39卷 14-18页

作者： Jing zhao Jinlei Liu Xiaowei Wang Jianmin Yuan zengxiu zhao Department of Physics National University of Defense TechnologyChangsha 410073China Graduate School of China Academic of Engineering Physics Beijing 100193China

We introduce and demonstrate a new approach to measure the electron-hole dynamics and coherence induced by strong-field ionization using hole-assisted high-harmonic *** coherent driving of the infrared and XUV pulses correlates the dynamics of the core-hole and the valence-hole by coupling multiple continua,which leads to the otherwise forbidden absorption and emission of high *** analytical model is developed based on the strong-field approximation by taking into account the essential multielectron *** emission spectra from the core-valence transition and the core-hole recombination are found to modulate strongly as functions of the time delay between the two pulses,suggesting that the coherent electron wave packets in multiple continua can be utilized to temporally resolve the core-valence transition in attoseconds.

关键词： coherent Strong Electron

Anisotropic coherence induced nonuniform amplification in N_(2)^(+)

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 17-23页

作者： Hongqiang Xie Qian Zhang Hongbin Lei Na Wang Yuhan Zheng Zhiming Chen Guihua Li zengxiu zhao School of Science East China University of TechnologyNanchang 330013China Department of Physics National University of Defense TechnologyChangsha 410073China School of Science East China Jiaotong UniversityNanchang 330013China

The continuous progress in N_(2)^(+) lasing recently stimulates a great deal of interest in nonlinear and quantum optics of molecular ions,while a complete description of the ionic polarization is still lacking to *** this work,we are dedicated to constructing the fundamental ionic polarization theory where several ubiquitous strong-field processes including ionization,electronic couplings and molecular alignment jointly determine the spatial arrangement of *** the model,the elusive polarization of N_(2)^(+) lasing can be well *** results show that the different electronic transition rules for strong-field ionization and resonant couplings result in peculiar population distributions of various electronic states of N_(2)^(+) in ***,the spatial nonuniformity of population distribution can be aggravated or mitigated during field-free evolutions of coherent molecular rotational wave ***,when a follow-up resonant seed pulse interacts with the prepared ionic system,the anisotropic quantum coherence determining the polarization of subsequent N_(2)^(+) lasing can be *** qualitative agreement between experiments and simulations confirms the validity of the proposed *** findings provide critical insights into the polarization and radiation mechanisms of molecular ions constructed via ultrafast laser pulses.

关键词： anisotropic coherence air lasing nonuniform amplification

Field intensity dependence of the dissociative multiple ionization of argon dimers in strong femtosecond laser fields

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 70-78页

作者： Pan Song Yalei Zhu Xiaowei Wang Congsen Meng Tao Jiang Zhihui Lv Dongwen Zhang Chaochao Qin zengxiu zhao Jianmin Yuan Department of Physics National University of Defense TechnologyChangsha 410073China Henan Key Laboratory of Infrared Spectrum Measures and Applications Schoolof PhysicsHenan NormalUniversityXinxiang 453007China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

The dissociative ionization of Ar dimers is investigated in femtosecond laser fields with intensities from 260 to 1020 TW/cm^(2).The three-dimensional momentum and kinetic-energy release of fragmental ions generated from the channels Ar_(2)^(2+)→Ar^(+)+Ar^(+),Ar_(2)^(3+)→Ar^(2+)+Ar^(+),and Ar_(2)^(4+)→Ar^(2+)+Ar^(2+)were measured with a cold-target recoil-ion momentum *** is shown that the laser intensity significantly modulates the kinetic energies and angular distributions of fragmental ions from dissociative double ***-induced charge-transfer following one-site double ionization contributes relatively more to the dissociative double ionization at lower laser *** calculation results of a one-dimensional model based on the WKB approximation suggest that the charge transfer is suppressed at higher laser intensity due to the core polarization *** addition,double,triple,and quadruple dissociative ionizations of Ar dimers are accompanied by frustrated-tunneling ionization that increases with the laser intensity.

关键词： femtosecond laser charge transfer Coulomb explosion frustrated tunneling ionization

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多电子动力学的强场调控与阿秒探测

科学通报 2021年第8期66卷 913-923页

作者：赵增秀国防科技大学文理学院物理系长沙410073

作为一种新型的超短极紫外/软X射线相干光源,阿秒脉冲推动了物质科学的新发展.它使得人们可以深入物质内部,对各种原子尺度的微观过程,以电子运动的自然时间尺度(1 as~10–^(18)s)实现前所未有的时空分辨和超快调控.阿秒脉冲的产生和应... 详细信息

作为一种新型的超短极紫外/软X射线相干光源,阿秒脉冲推动了物质科学的新发展.它使得人们可以深入物质内部,对各种原子尺度的微观过程,以电子运动的自然时间尺度(1 as~10–^(18)s)实现前所未有的时空分辨和超快调控.阿秒脉冲的产生和应用与强激光脉冲驱动的物质内电子亚周期的超快动力学密切相关.对其的研究,有助于在时域、相位、纠缠等方面理解电子关联如何影响物质性质和动力学,回答光是如何被原子、分子或者固体吸收的,光电离时间、隧穿时间、电子迁移时间是否存在等基本科学问题.虽然未来阿秒脉冲光源发展仍有待进一步增大光强和压缩脉宽,但是目前结合超强的激光脉冲和超短的阿秒光源,有可能在新的能量域、时间域、空间域实现电子动力学的强场调控和阿秒探测,为未来拍赫兹光电子学、阿秒瞬态光谱等新的物质科学与信息技术奠定基础.本文将回顾强场和超快物理在实验、理论、技术和应用上带来的推动,聚焦电子和多电子动力学的强场效应和时域探测,介绍部分相关领域的发展.

关键词：阿秒脉冲高次谐波强场隧穿电离电子关联

Nonresonant Multiphoton Ionization of Stark Decelerated Molecules by Femtosecond Laser Pulses

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Chinese Physics Letters 2022年第11期39卷 18-21页

作者： Congsen Meng Zhihui Lü Xiaowei Wang Dongwen Zhang zengxiu zhao Jianmin Yuan Department of Physics National University of Defense TechnologyChangsha 410073China Department of Physics Graduate School of China Academy of Engineering PhysicsBeijing 100193China

Nonresonant multiphoton ionization by femtosecond laser pulses can be applied to any molecule virtually,thereby greatly enhancing the scope of Stark decelerated *** comparison,we detect decelerated and trapped ammonia molecules using two different schemes:(ⅰ) nonresonant multiphoton ionization using intense femtosecond(fs) pulses in the near infrared,and(ⅱ) resonance-enhanced multiphoton ionization using nanosecond(ns) pulses from a tunable UV *** observed number of ions per shot for both schemes is *** fs laser detection scheme suffers from an increased background,which can be effectively eliminated by subsequent mass and velocity *** determine the detection volume of the ns laser detection scheme,we present measurements in which the decelerated ammonia molecules are bunched to a packet with a longitudinal spread well below~100 μ*** is concluded that the detection volume for the ns laser detection scheme is 1.5-2 times larger than that of the fs laser detection scheme.

关键词： Femto scheme Stark

Decoherence Effects of Terahertz Generation in Solids under Two-Color Femtosecond Laser Fields

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Chinese Physics Letters 2022年第5期39卷 36-41页

作者： Qifang Peng zhaoyang Peng Yue Lang Yalei Zhu Dongwen Zhang Zhihui Lü zengxiu zhao Department of Physics College of Liberal Arts and SciencesNational University of Defense TechnologyChangsha 410073China

We theoretically investigate terahertz emission from solid materials pumped by intense two-color femtosecond laser field in the presence of decoherence ***-mechanical simulations are based on the length gauge semiconductor Bloch equations describing the optical excitation and decoherence with phenomenological dephasing and depopulation *** of interband and intraband mechanisms are identified in time domain,and the latter has dominated THz generation in solid-state *** is found that dephasing is crucial for enhancing asymmetric intraband current and deduced that solid-state materials with short dephasing time and long depopulation time would be optimal selection for strong-field terahertz generation experiments.

关键词： pumped Femto Solid

Generation of 88 as Isolated Attosecond Pulses with Double Optical Gating

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Chinese Physics Letters 2020年第2期37卷 11-14页

作者： Xiaowei Wang Li Wang Fan Xiao Dongwen Zhang Zhihui Lü Jianmin Yuan zengxiu zhao Department of Physics National University of Defense TechnologyChangsha 410073 Department of Physics Graduate School of China Academy of Engineering PhysicsBeijing 100193 IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240

Isolated attosecond pulses with a duration of 88 as are generated in the spectral range of 29–72 eV using double optical gating *** gate width is set to be shorter than half the optical cycle to avoid carrier envelop phase stabilization of the 4.2 fs driving laser pulses centered at 800 *** attosecond pulse duration is measured with the technique of frequency resolved optical gating for complete reconstruction of attosecond bursts.

关键词： technique. second stabilization

全X射线阿秒泵浦-阿秒探测实现液态水中电子动力学测量

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科学通报 2024年第14期69卷 1815-1817页

作者：赵晶赵增秀国防科技大学理学院物理系长沙410073

实时追踪物质内部电子的运动是实现量子物态超快调控的关键,阿秒光脉冲为物质内部电子动力学探测提供了前所未有的时空分辨工具.目前,阿秒光脉冲产生主要来源于飞秒强激光作用于惰性气体产生的高次谐波辐射,利用阿秒脉冲与红外激光的互... 详细信息

实时追踪物质内部电子的运动是实现量子物态超快调控的关键,阿秒光脉冲为物质内部电子动力学探测提供了前所未有的时空分辨工具.目前,阿秒光脉冲产生主要来源于飞秒强激光作用于惰性气体产生的高次谐波辐射,利用阿秒脉冲与红外激光的互关联实现阿秒时间分辨的动力学测量.人们已经开展了对原子和团簇中光电离时间延迟^([1,2])、强场电离诱导的价电子运动^([3])、自电离动力学^([4])、分子中的电荷迁移^([5])和锥间交叉^([6])等重要基础物理问题的研究.

关键词：基础物理电荷迁移光电离红外激光液态水时间延迟 X射线互关联