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Theoretical investigation of excited dipole bound states of alkali-containing diatomic anions

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Chinese physics B 2024年第5期33卷 389-393页

作者：连艺肖利丹边丽丽徐海峰闫冰 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

Information about electronic excited states of molecular anions plays an important role in investigating electron attachment and detachment processes.Here we present a high-level theoretical study of the electronic structures of 12 alkali-metal-containing diatomic anions MX-(MX = LiH,LiF,LiCl,NaF,NaCl,NaBr,RbCl,KCl,KBr,RbI,KI and CsI).The equation-of-motion electron-attachment coupled-cluster singles and doubles(EOM-EA-CCSD) method is used to calculate the electron binding energies(EBEs) of 10 electronic excited states of each of the 12 molecule anions.With addition of different s-/p-/d-type diffusion functions in the basis set,we have identified possible excited dipole bound states(DBSs) of each anion.With the investigation of EBEs on the 12 MXs with dipole moment(DM) up to 12.1 D,we evaluate the dependence of the number of anionic excited DBSs on molecular DM.The results indicate that there are at least two or three DBSs of anions with a molecular DM larger than 7 D and a molecule with DM > 10 D can sustain a π-DBS of the anion.Our study has some implications for the excited DBS electronic states of alkali-metal-containing diatomic molecules.

关键词： anions dipole bound states alkali-metal-containing diatomic molecules

Generation of Ultrafast Attosecond Magnetic Field from Ne Dimer in Circularly Polarized Laser Pulses

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Chinese physics Letters 2023年第11期40卷 37-41页

作者：闫淑娟徐清芸郝欣宇郭颖郭静 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

By numerically solving time-dependent Schr?dinger equations,we investigate the generation of electron currents,ultrafast magnetic fields and photoelectron momentum distributions(PMD) when circularly polarized laser pulses interact with a Ne dimer in the charge migration(CM) process.By adjusting the laser wavelength,we consider two cases:(i) coherent resonance excitation(λ=76 nm) and(ii) direct ionization(λ=38 nm).The results show that the current and magnetic field generated by the Ne dimer under resonance excitation are stronger than under direct ionization.This phenomenon is due to the quantum interference between the initial state 2pσ_(g) and the excited state 3sσ_(g) under resonance excitation,so the CM efficiency of the dimer can be improved and the strength of the PMD under different ionization conditions is opposite to the strength of the electron current and induced magnetic field.In addition,we also find that both 2pπ_(g) and 2pπ_(u) have coherent resonance excitation with 3sσ_(g) state and generate periodic oscillating currents for the Ne dimer.The study of the dynamics of the Ne dimer under different ionization conditions lays a foundation for research of ultrafast magnetism in complex molecular systems.

关键词： excitation coherent oscillating

Generation of elliptical isolated attosecond pulse from oriented H_(2)^(+)in a linearly polarized laser field

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Chinese physics B 2022年第4期31卷 281-286页

作者：邢云鹤张军霍晓鑫徐清芸刘学深 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

We investigate the ellipticity of the high-order harmonic generation from the oriented H_(2)^(+)exposed to a linearly polarized laser field by numerically solving the two-dimensional time-dependent Schrodinger equation(2 D TDSE).Numerical simulations show that the harmonic ellipticity is remarkably sensitive to the alignment angle.The harmonic spectrum is highly elliptically polarized at a specific alignment angleθ=30°,which is insensitive to the variation of the laser parameters.The position of the harmonic intensity minima indicates the high ellipticity,which can be attributed to the two-center interference effect.The high ellipticity can be explained by the phase difference of the harmonics.This result facilitates the synthesis of a highly elliptical isolated attosecond pulse with duration down to 65 as,which can be served as a powerful tool to explore the ultrafast dynamics of molecules and study chiral light-matter interaction.

关键词： high harmonic generation linearly polarized laser fields elliptical isolated attosecond pulse alignment angle two-center interference effect

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：李孝开余西涛马盼赵欣宁王春成罗嗣佐丁大军 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

Photoelectron momentum distributions of Ne and Xe dimers in counter-rotating circularly polarized laser fields

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Chinese physics B 2022年第6期31卷 291-299页

作者：雷志仙徐清芸杨志杰何永林郭静 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

The strong-field ionization of dimers is investigated theoretically in counter-rotating circularly polarized laser fields.By numerically solving the two-dimensional(2D)time-dependent Schrödinger equation(TDSE)with the single-electron approximation(SEA)frame,we present the photoelectron momentum distributions(PMDs)and photoelectron angular distribution(PADs)of aligned Ne and Xe dimers.It is found that the PMDs and PADs strongly depend on the time delays by counter-rotating circularly polarized laser pulses.The results can be explained by the ultrafast photoionization model and the evolution of electron wave packets for Ne and Xe dimers.Besides,We make a comparison of PMDs between Ne atom and Ne dimer.

关键词： time-dependent Schrödinger equation dimer photoelectron momentum distributions ultrafast photoionization model

The momentum distributions of triatomic molecular ion H_(3)^(2+) by intense laser pulses

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Communications in Theoretical physics 2023年第6期75卷 112-119页

作者： Zhi-Xian Lei Shu-Juan Yan Xin-Yu Hao Pan Ma Sheng-Peng Zhou Jing Guo Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

We investigate theoretically the photoionization of triatomic molecular ion H_(3)^(2+) by numerically solving the two-dimensional time-dependent Schrödinger equations under Bohn-Oppenheimer approximation.The results show that the photoelectron momentum distributions(PMDs)of H_(3)^(2+) with different initial states are strongly dependent on the laser ellipticities and molecular orbital symmetry,and the PMDs of degenerate electronic states E^(±)are mirror images.Also,for degenerate electronic states E^(±),vortex structures appear in the PMDs by the counter-rotating circularly polarized laser pulses as the time delay between the two pulses increases,which can be explained by multicenter ionization and ultrafast photoionization model.

关键词： momentum distribution ringlike molecules intense laser fields

Spectral redshift of high-order harmonics by adding a weak pulse in the falling part of the trapezoidal laser pulse

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Chinese physics B 2018年第2期27卷 374-379页

作者：潘雪飞张军贲帅徐彤彤刘学深 Institute of Atomic and Molecular Physics Jilin University

We investigate the spectral redshift of high-order harmonics of the H_2~＋（D_2~＋） molecule by numerically solving the non-Born–Oppenheimer time-dependent Schr ¨odinger equation（TDSE）. The results show that the spectral redshift of highorder harmonics can be observed by adding a weak pulse in the falling part of the trapezoidal laser pulses. Comparing with the H_2~＋ molecule, the shift of high-order harmonic generation（HHG） spectrum for the D_2~＋ molecule is more obvious.We employ the spatial distribution in HHG and time-frequency analysis to illustrate the physical mechanism of the spectral redshift of high-order harmonics.

关键词： high-order harmonic generation spectral redshift trapezoidal laser pulse spatial distribution

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：徐彤彤陈佳贺潘雪飞张宏丹贲帅刘学深 Institute of Atomic and Molecular Physics Jilin University

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

Effect of sample temperature on femtosecond laser ablation of copper

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Chinese physics B 2024年第2期33卷 377-385页

作者：党伟杰陈雨桐陈安民金明星 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied atomic and molecular Spectroscopy Jilin UniversityChangchun 130012China

We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of ablation morphology and lattice temperature.For investigating the effect of sample temperature on femtosecond laser processing,we conduct experiments on and simulate the thermal behavior of femtosecond laser irradiating copper by using a two-temperature model.The simulation results show that both electron peak temperature and the relaxation time needed to reach equilibrium increase as initial sample temperature rises.When the sample temperature rises from 300 K to 600 K,the maximum lattice temperature of the copper surface increases by about 6500 K under femtosecond laser irradiation,and the ablation depth increases by 20%.The simulated ablation depths follow the same general trend as the experimental values.This work provides some theoretical basis and technical support for developing femtosecond laser processing in the field of metal materials.

关键词： femtosecond laser two-temperature model sample temperature ablation depth