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Core level excitation spectra of La and Mn ions in LaMnO3

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Chinese physics B 2024年第3期33卷 327-332页

作者：李福建程新路张红 institute of atomic and molecular physics Sichuan UniversityChengdu 610065Chin

Manganese-based perovskite is popular for research on ferromagnetic materials,and its spectroscopic studies are essential for understanding its electronic structure,dielectric,electrical,and magnetic *** this paper,the M-edge spectra of La ions and the M-edge,L-edge,and K-edge spectra of Mn ions in LaMnO3 are calculated by considering both the free-ion multiplet calculation and the crystal field *** analyze spectral shapes,identify peak origins,and estimate the oxidation states of La and Mn ions in LaMnO3 *** is concluded that La ions in LaMnO3 predominantly exist in the trivalent state,while Mn ions exist primarily in the trivalent state with a minor presence of tetravalent ***,the calculated spectra are in better conformity with the experimental spectra when the proportion of Mn3+is 90%and Mn4+is 10%.This article enhances our comprehension of the oxidation states of La and Mn within the crystal and also provides a valuable guidance for spectroscopic investigations of other manganates.

关键词： lanthanum manganate the core level excitation spectra free-ion multiplet calculation oxidation state

Photoelectron momentum distributions of triatomic CO_(2)molecules by circularly polarized attosecond pulses

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Chinese physics B 2024年第10期33卷 220-225页

作者： Si-Qi Zhang Jun Zhang Xin-Yu Hao Jing Guo Aihua Liu Xue-Shen Liu institute of atomic and molecular physics Jilin UniversityChangchun 130012China School of physics Harbin Institute of TechnologyHarbin 150001China

molecular-frame photoelectron momentum distributions(MF-PMDs)have been studied for imaging molecular *** investigate the MF-PMDs of CO_(2)molecules exposed to circularly polarized(CP)attosecond laser pulses bysolving the time-dependent Schrodinger equations based on the single-active-electron approximation *** showthat high-frequency photons lead to photoelectron diffraction patterns,indicating molecular *** diffractionpatterns can be illustrated by the ultrafast photoionization ***,for the driving pulses with 30 nm,a deviationbetween MF-PMDs and theoretically predicted results of the ultrafast photoionization models is produced because theCoulomb effect strongly influences the molecular ***,the MF-PMDs rotate in the same directionas the helicity of driving laser *** results also demonstrate that the MF-PMDs in a CP laser pulse are the superpositionof those in the parallel and perpendicular linearly polarized *** simulations efficiently visualize molecularorbital geometries and structures by ultrafast photoelectron ***,we determine the contribution of HOMOand HOMO-1 orbitals to ionization by varying the relative phase and the ratio of these two orbitals.

关键词： molecular-frame photoelectron momentum distributions single-active-electron approximation frames ultrafast photoionization models

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 *** 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 *** addition of different s-/p-/d-type diffusion functions in the basis set,we have identified possible excited dipole bound states(DBSs) of each *** 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 *** 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 *** 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

Low-energy inelastic electron scattering from carbon monoxide:Excitation and de-excitation of the X^(1)Σ^(+),a^(3)Π,a'^(3)∑^(+),A^(1)Π,d^(3)Δ,e^(3)∑^(-),I^(1)∑^(-)and D^(1)Δelectronic states

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Chinese physics B 2024年第4期33卷 444-450页

作者：卫鹏宇黄朝文程新路张红 institute of atomic and molecular physics Sichuan UniversityChengdu 610065China College of physics Sichuan UniversityChengdu 610065China

Cross-sections for electronic excitation and de-excitation among the ground state and lowest-lying seven electronic excited states of carbon monoxide(CO)by low-energy electron impact are computed using the R-matrix *** excitation cross-sections from the ground state to the electronic states a^(3)Π,a'^(3)Σ^(+)+and A^(1)Πagree with previous experimental and theoretical *** addition,the cross-sections for the I^(1)Σ^(+)-and D^(1)Δstates of CO,which will cascade to CO a'^(3)Σ^(+)+and A^(1)Πstates,are ***,in contrast to the typical increase in electronic excitation cross-sections with collision energy,the de-excitation cross-sections show a negative trend with increasing energy.

关键词： electron-CO collision electronic excitation cross-sections R-matrix method

Deciphering TADF Mechanisms in Metal-Free Organic Emitters BrA-HBI:Utilizing Optimally Tuned Range-Separated Functionals for Insight

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Chinese physics Letters 2024年第9期41卷 28-37页

作者： Chunyue Yu Hang Yin Jie Guo Wentian Zhang Ying Shi institute of atomic and molecular physics Jilin UniversityChangchun 130012China

Metal-free organic emitters,characterized by their thermally activated delayed fluorescence(TADF)properties,offer considerable promise for the creation of highly efficient organic light-emitting diodes(OLEDs).Recently,Shao et *** a novel excited state intramolecular proton transfer(ESIPT)system BrA-HBI,demonstrating an emission quantum yield of up to 50%[***.32,2201256(2022)].However,many open issues cannot be answered solely by experimental means only and require detailed theoretical *** instance,what causes the activation of TADF from the Keto*tautomer and leads to fluorescence quenching in the Enol^(*)form?Herein,we provide a theoretical investigation on the TADF mechanism of the BrA-HBI molecule by optimally tuned range-separated *** findings reveal that ESIPT occurs in the BrA-HBI ***,we have disclosed the reason for the fluorescence quenching of the Enol^(*)form and determined that the T_(2)state plays a dominant role in the TADF *** addition,double hybrid density functionals method was utilized to verify the reliability of optimally tuned range separation functionals on the calculation of the TADF mechanism in *** findings not only provide a theoretical reference for development of highly efficient organic light-emitting diodes,but also demonstrate the effectiveness of the optimally tuned range-separated functionals in predicting the luminescence properties of TADF molecules.

关键词： optimal finding separated

Pressure-Driven Energy Band Gap Narrowing of λ-N_(2)

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Chinese physics Letters 2024年第4期41卷 173-177页

作者：李月刘静仪吴彬彬陶雨耿延雷王晓丽雷力 institute of atomic and molecular physics Sichuan UniversityChengdu 610065China School of physics and Electronic Information Yantai UniversityYantai 264005China

Probing the energy band gap of solid nitrogen at high pressures is of importance for understanding pressuredriven changes in electronic structures and insulator-to-metal transitions under high *** λ-N_(2) formed by cold compression is known to be the most stable one in all solid nitrogen phases observed so *** optimizing the optical system,we successfully measured the high-pressure absorption spectra of λ-N_(2) covering the polymericnitrogen synthetic pressures(124 GPa-165 GPa).The measured optical band gap decreases with increasing pressure,from 2.23 eV at 124 GPa to 1.55 eV at 165 GPa,with a negative pressure coefficient of-18.4 meV/GPa,which is consistent with the result from our ab initio total-energy calculations(-22.6 meV/GPa).The extrapolative metallization pressure for theλ-N_(2) is around 288(18)GPa,which is close to the metallization pressure(280 GPa)for the η-N_(2) expected by previous absorption edge and direct electrical *** results provide a direct spectroscopic evidence for the pressure-driven band gap narrowing of solid nitrogen.

关键词： absorption transitions spectroscopic

Optimization of extreme ultraviolet vortex beam based on high harmonic generation

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Chinese physics B 2024年第5期33卷 459-464页

作者：肖礴赵逸文程方晶王革文姜威王一琛胡杰梁红静马日 institute of atomic and molecular physics Jilin UniversityChangchun 130012China College of Science Jilin Institute of Chemical TechnologyJilin 132022China

In high harmonic generation(HHG),Laguerre–Gaussian(LG) beams are used to generate extreme ultraviolet(XUV)vortices with well-defined orbital angular momentum(OAM),which have potential applications in fields such as microscopy and *** experimental study on the HHG driven by vortex and Gaussian beams is conducted in this *** is found that the intensity of vortex harmonics is positively correlated with the laser energy and gas *** structure and intensity distribution of the vortex harmonics exhibit significant dependence on the relative position between the gas jet and the laser *** ring-like structures observed in the vortex harmonics,and the interference of quantum paths provide an explanation for the distinct structural ***,by adjusting the relative position between the jet and laser focus,it is possible to discern the contributions from different quantum *** optimization of the HH vortex field is applicable to the XUV,which opens up a new way for exploiting the potential in optical spin or manipulating electrons by using the photon with tunable orbital angular momentum.

关键词： high harmonic generation phase matching extreme ultraviolet vortex beam quantum path interference

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

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 *** 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 *** simulation results show that both electron peak temperature and the relaxation time needed to reach equilibrium increase as initial sample temperature *** 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 *** 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