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Direct Observation on H-Elimination Enhancement from C_(2)H_(4) through Non-Adiabatic Process by Femtosecond Laser Induced Coulomb Explosion

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Chinese Physics Letters 2024年第5期41卷 17-22页

作者：金无维王春成赵晓戈杨译章任殿相刘泽槿李孝开罗嗣佐丁大军 Institute of atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial key laboratory of Applied atomic and Molecular Spectroscopy Jilin UniversityChangchun 130012China

Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurements, we investigate the ultrafast non-adiabatic dynamics involved in the breakage of carbon-carbon double bonds and hydrogen elimination in dissociation of ethylene. Our study entails analyzing the dynamic kinetic energy release spectra to assess three bond-breaking scenarios, movements of nuclei, and structural changes around the carbon atoms. This allows us to evaluate the relaxation dynamics and characteristics of various dissociative states. Notably, we observe a significant rise in the yield of fragments resulting from C–H bond breakage with the delay time extended, suggesting non-adiabatic coupling through conical intersections from C–C bond breakage as a probable cause.

关键词： pump Femto adiabatic

Theoretical investigation of electron-impact ionization of W8+ion

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Chinese Physics B 2024年第3期33卷 341-349页

作者：张世平张芳军张登红丁晓彬蒋军颉录有马玉龙李麦娟 Marek Sikorski 董晨钟 key laboratory of atomic and Molecular Physics & Functional Materials of Gansu Province College of Physics and Electronic EngineeringNorthwest Normal UniversityLanzhou 730070China

The electron-impact single ionization cross section for W8+ion has been calculated using flexible atomic code,employing the level-to-level distorted-wave *** calculations takes into account contributions form both direct ionization(DI)and excitation autoionization(EA).However,the theoretical predictions,based solely on the ground state,tends to underestimate the experimental *** discrepancy can be mitigated by incorporation contributions from excited *** extended the theoretical analysis,including the contributions from the long-lived metastable states with lifetimes exceeding 1.5×10-5 *** employed two statistical models to predict the fraction of ground state ions in the parent ion *** a 79%fraction of parent ions in ground configuration,the experiment measurements align with the *** we derived the theoretical cross-section for the ground state as correlated plasma rate coefficients,and compared it with existing *** the uncertainty in our calculations,our results are still acceptable.

关键词： tungsten ions electron-impact ionization cross section

Rationally construction of atomic-precise interfacial charge transfer channel and strong build-in electric field in nanocluster-based Zscheme heterojunctions with enhanced photocatalytic hydrogen production

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Nano Research 2024年第6期17卷 5002-5010页

作者： Qingtao Zhu Honglei Shen Chao Han Liu Huang Yanting Zhou Yuanxin Du Xi Kang Manzhou Zhu Department of Materials Science and Engineering Centre for Atomic Engineering of Advanced MaterialsKey Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationKey Laboratory of Functional Inorganic Material Chemistry of Anhui ProvinceAnhui UniversityHefei 230601China

The lack of effective charge transfer driving force and channel limits the electron directional migration in nanoclusters(NC)-based heterostructures,resulting in poor photocatalytic ***,a Z-scheme NC-based heterojunction(Pt1Ag28-BTT/CoP,BTT=1,3,5-benzenetrithiol)with strong internal electric field is constructed via interfacial Co-S bond,which exhibits an absolutely superiority in photocatalytic performance with 24.89 mmol·h^(−1)·g−1 H_(2)production rate,25.77%apparent quantum yield at 420 nm,and~100%activity retention in stability,compared with Pt1Ag28-BDT/CoP(BDT=1,3-benzenedithiol),Ag29-BDT/CoP,and *** enhanced catalytic performance is contributed by the dual modulation strategy of inner core and outer shell of NC,wherein,the center Pt single atom doping regulates the band structure of NC to match well with CoP,builds internal electric field,and then drives photogenerated electrons steering;the accurate surface S modification promotes the formation of Co-S atomic-precise interface channel for further high-efficient Z-scheme charge directional *** work opens a new avenue for designing NC-based heterojunction with matchable band structure and valid interfacial charge transfer.

关键词： atomically precise metal nanocluster Z-scheme heterojunction interfacial charge transfer build-in electric field photocatalytic hydrogen production

Recent advances in morphology control of platinum catalysts toward oxygen reduction reaction

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Frontiers in Energy 2024年第3期18卷 330-355页

作者： Shun CHEN Yanru LIU Xiaogang FU Wanglei WANG State key laboratory of Solidification Processing Atomic Control and Catalysis Engineering LaboratorySchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China State key laboratory of Oral and Maxillofacial Reconstruction and Regeneration National Clinical Research Center for Oral DiseasesShaanxi Key Laboratory of StomatologyDepartment of Dental MaterialsSchool of StomatologyThe Fourth Military Medical UniversityXi’an 710032China

Exploring advanced platinum (Pt)-based electrocatalysts is vital for the widespread implementation of proton exchange membrane fuel cells (PEMFCs). Morphology control represents an effective strategy to optimize the behavior of Pt catalysts. In this work, an attempt is made to comprehensively review the effect of morphology control on the catalytic behavior of catalysts in the oxygen reduction reaction (ORR). First, the fundamental physicochemical changes behind morphology control, including exposing more active sites, generating appropriate lattice strains, and forming different crystalline surfaces, are highlighted. Then, recently developed strategies for tuning the morphologies of electrocatalysts, including core-shell structures, hollow structures, nanocages, nanowires, and nanosheets, are comprehensively summarized. Finally, an outlook on the future development of morphology control of Pt catalysts is presented, including rational design strategies, advanced in situ characterization techniques, novel artificial intelligence, and mechanical learning. This work is intended to provide valuable insights into designing the morphology and technological innovation of efficient redox electrocatalysts in fuel cells.

关键词： morphology platinum catalysts electrocatalysis ORR PEMFC

Simulation of optimal work extraction for quantum systems with work storage

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Chinese Physics B 2024年第2期33卷 195-203页

作者：宋鹏飞张旦波 key laboratory of atomic and Subatomic Structure and Quantum Control(Ministry of Education) and School of PhysicsSouth China Normal UniversityGuangzhou 510006China Guangdong Provincial key laboratory of Quantum Engineering and Quantum Materials Guangdong–Hong Kong Joint Laboratory of Quantum Matterand Frontier Research Institute for PhysicsSouth China Normal UniversityGuangzhou 510006China

The capacity to extract work from a quantum heat machine is not only of practical value but also lies at the heart of understanding quantum *** this paper,we investigate optimal work extraction for quantum systems with work storage,where extracting work is completed by a unitary evolution on the composite *** consider the physical requirement of energy conservation both strictly and on *** both,we construct their corresponding unitaries and propose variational quantum algorithms for optimal work *** show that maximal work extraction in general can be feasible when energy conservation is satisfied on *** demonstrate with numeral simulations using a continuous-variable work *** work show an implementation of a variational quantum computing approach for simulating work extraction in quantum systems.

关键词： quantum algorithm quantum thermodyanmics

Uncertainties of nuclear level density estimated using Bayesian neural networks

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Chinese Physics C 2024年第8期48卷 185-189页

作者： Xinyu Wang Ying Cui Yuan Tian Kai Zhao Yingxun Zhang China Institute of atomic Energy Beijing 102413China China Nuclear Data Center China Institute of Atomic EnergyBeijing 102413China Guangxi key laboratory of Nuclear Physics and Technology Guangxi Normal UniversityGuilin 541004China

Nuclear level density(NLD)is a critical parameter for understanding nuclear reactions and the structure of atomic nuclei;however,accurate estimation of NLD is challenging owing to limitations inherent in both experimental measurements and theoretical *** paper presents a sophisticated approach using Bayesian neural networks(BNNs)to analyze NLD across a wide range of *** uniquely incorporates the assessment of model *** application of BNNs demonstrates remarkable success in accurately predicting NLD values when compared to recent experimental data,confirming the effectiveness of our *** reliability and predictive power of the BNN approach not only validates its current application but also encourages its integration into future analyses of nuclear reaction cross sections.

关键词： Bayesian neural network nuclear reaction nuclear level density

Modulation of High-Order Harmonic Generation from a Monolayer ZnO by Co-rotating Two-Color Circularly Polarized Laser Fields

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Chinese Physics Letters 2024年第1期41卷 34-38页

作者：乔月陈家祺周书山陈基根蒋士成杨玉军 School of Materials Science and Engineering Taizhou UniversityJiaojiang 318000China Institute of atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial key laboratory of Applied atomic and Molecular Spectroscopy(Jilin University) Changchun 130012China School of Physics and Electronic Technology Liaoning Normal UniversityDalian 116029China State key laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China

By numerically solving the two-dimensional semiconductor Bloch equation,we study the high-order harmonic emission of a monolayer ZnO under the driving of co-rotating two-color circularly polarized laser *** changing the relative phase between the fundamental frequency field and the second one,it is found that the harmonic intensity in the platform region can be significantly *** the higher order,the harmonic intensity can be increased by about one order of *** time-frequency analysis,it is demonstrated that the emission trajectory of monolayer ZnO can be controlled by the relative phase,and the harmonic enhancement is caused by the second quantum trajectory with the higher emission *** addition,near-circularly polarized harmonics can be generated in the co-rotating two-color circularly polarized *** the change of the relative phase,the harmonics in the platform region can be altered from left-handed near-circularly polarization to right-handed *** results can obtain high-intensity harmonic radiation with an adjustable ellipticity,which provides an opportunity for syntheses of circularly polarized attosecond pulses.

关键词： polarization rotating harmonic

In situ calibrated angle between the quantization axis and the propagating direction of the light field for trapping neutral atoms

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Chinese Physics B 2024年第2期33卷 318-323页

作者：郭瑞军何晓东盛诚王坤鹏许鹏刘敏王谨孙晓红曾勇詹明生 Henan key laboratory of Laser and Optoelectronic Information National Center for International Joint Research of Electronic Materials and SystemsSchool of Electrical and Information EngineeringZhengzhou UniversityZhengzhou 450001China State key laboratory of Magnetic Resonance and atomic and Molecular Physics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constantdepth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic ***, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.

关键词： quantization axis trapping laser angle compensating magnetic fields

Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse

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Chinese Physics B 2024年第3期33卷 433-440页

作者：王源李玉龙乔月高娜郭福明陈洲赫兰海杨玉军赵曦王俊 Institute of atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial key laboratory of Applied atomic and Molecular Spectroscopy Jilin UniversityChangchun 130012China Beijing Institute of Space Launch Technology Beijing 100076China School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710062China

We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping *** findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping *** phenomenon holds potential significance for experimental setups necessitating precisely tuned single ***,we observe a modulated shift in the created harmonic photon energy,spanning an impressive range of 1.2 *** frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse,directly influencing the position of the peak frequency *** study quantifies the dependence of this tuning range and the asymmetry of the laser pulse,offering valuable insights into the underlying mechanisms driving this ***,our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is *** attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return *** observation introduces an innovative approach for generating semi-integer order harmonics,thus expanding our understanding of high-order harmonic ***,our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications,particularly those involving precise spectral control and the generation of unique harmonic patterns.

关键词： high-order harmonic semi-integer-order spectra shift inhomogeneous field