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Modulation of High-Order Harmonic Generation from a Monolayer ZnO by Co-rotating Two-Color Circularly Polarized Laser Fields 被引量:1
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作者 乔月 陈家祺 +3 位作者 周书山 陈基根 蒋士成 杨玉军 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第1期34-38,共5页
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 pulses.By chan... 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 pulses.By 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 modulated.In the higher order,the harmonic intensity can be increased by about one order of magnitude.Through 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 probability.In addition,near-circularly polarized harmonics can be generated in the co-rotating two-color circularly polarized fields.With the change of the relative phase,the harmonics in the platform region can be altered from left-handed near-circularly polarization to right-handed one.Our results can obtain high-intensity harmonic radiation with an adjustable ellipticity,which provides an opportunity for syntheses of circularly polarized attosecond pulses. 展开更多
关键词 POLARIZATION ROTATING HARMONIC
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Generation of quasi-chirp-free isolated attosecond pulses from atoms under the action of orthogonal two-color combined pulse of fundamental frequency and higher intensity second harmonic fields
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作者 蔚瑞贤 乔月 +5 位作者 李萍 王俊 陈基根 冯伟 郭福明 杨玉军 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第6期218-225,共8页
The intrinsic chirp of high-order harmonic generation is an important factor limiting the production of ultrashort attosecond pulses.Based on numerically solving the time-dependent Schrodinger equation,the generation ... The intrinsic chirp of high-order harmonic generation is an important factor limiting the production of ultrashort attosecond pulses.Based on numerically solving the time-dependent Schrodinger equation,the generation process of highorder harmonic from the He atom under the action of orthogonal two-color combined pulse of fundamental frequency and higher intensity second harmonic fields is studied.In this paper,we propose to achieve quasi-chirp-free isolated attosecond pulses by superimposing a higher second-harmonic field on the orthogonal direction of the fundamental frequency field.It is found that the high-energy part of its harmonic emission exhibits small chirp characteristics,which can be used to synthesize isolated attosecond pulses.Through the analysis of the wave packets evolution and the classical motion trajectories of the electron,it is demonstrated that the quasi-chirp-free harmonic can be attributed to the simultaneous return of electrons ionized at different times to the parent particle.The influence of the relative phase of the two pulses on the harmonics is further analyzed,and it is observed that this phenomenon is sensitive to the relative phase,but it can still generate isolated attosecond pulses within a certain phase. 展开更多
关键词 high-order harmonic orthogonal two-color fields relative phase quasi-chirp-free isolated attosecond pulses
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Effect of sample temperature on femtosecond laser ablation of copper
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作者 党伟杰 陈雨桐 +1 位作者 陈安民 金明星 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期377-385,共9页
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... 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. 展开更多
关键词 femtosecond laser two-temperature model sample temperature ablation depth
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Internal collision double ionization of molecules driven by co-rotating two-color circularly polarized laser pulses
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作者 李雪峰 乔月 +5 位作者 吴丹 蔚瑞贤 陈基根 王俊 郭福明 杨玉军 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期355-361,共7页
The double ionization process of molecules driven by co-rotating two-color circularly polarized fields is investigated with a three-dimensional classical ensemble model. Numerical results indicate that a considerable ... The double ionization process of molecules driven by co-rotating two-color circularly polarized fields is investigated with a three-dimensional classical ensemble model. Numerical results indicate that a considerable part of the sequential double ionization(DI) events of molecules occur through internal collision double ionization(ICD), and the ICD recollision mechanism is significantly different from that in non-sequential double ionization(NSDI). By analyzing the results of internuclear distances R = 5 a.u. and 2 a.u., these two recollision mechanisms are studied in depth. It is found that the dynamic behaviors of the recollision mechanisms of NSDI and ICD are similar. For NSDI, the motion range of electrons after the ionization is relatively large, and the electrons will return to the core after a period of time. In the ICD process,electrons will rotate around the parent ion before ionization, and the distance of the electron motion is relatively small. After a period of time, the electrons will come back to the core and collide with another electron. Furthermore, the molecular internuclear distance has a significant effect on the electron dynamic behavior of the two ionization mechanisms. This study will help to understand the multi-electron ionization process of complex systems. 展开更多
关键词 non-sequential double ionization internuclear distance internal-collision circularly polarized laser field
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Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse
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作者 王源 李玉龙 +7 位作者 乔月 高娜 郭福明 陈洲 赫兰海 杨玉军 赵曦 王俊 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期433-440,共8页
We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse.Our findings reveal an intriguing manipulation of the frequency peak position... We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse.Our 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 pulse.This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics.Notably,we observe a modulated shift in the created harmonic photon energy,spanning an impressive range of 1.2 eV.This 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 emission.Our study quantifies the dependence of this tuning range and the asymmetry of the laser pulse,offering valuable insights into the underlying mechanisms driving this phenomenon.Furthermore,our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is altered.We attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return cores.This observation introduces an innovative approach for generating semi-integer order harmonics,thus expanding our understanding of high-order harmonic generation.Ultimately,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. 展开更多
关键词 high-order harmonic semi-integer-order spectra shift inhomogeneous field
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Effect of distances between lens and sample surface on laser-induced breakdown spectroscopy with spatial confinement
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作者 Zhenhua JIANG Junfeng SHAO +4 位作者 Tingfeng WANG Jin GUO Dan ZHANG Anmin CHEN Mingxing JIN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第8期74-81,共8页
Spatial confinement can significantly enhance the spectral intensity of laser-induced plasma in air. It is attributed to the compression of plasma plume by the reflected shockwave. In addition,optical emission spectro... Spatial confinement can significantly enhance the spectral intensity of laser-induced plasma in air. It is attributed to the compression of plasma plume by the reflected shockwave. In addition,optical emission spectroscopy of laser-induced plasma can also be affected by the distance between lens and sample surface. In order to obtain the optimized spectral intensity, the distance must be considered. In this work, spatially confined laser-induced silicon plasma by using a Nd:YAG nanosecond laser at different distances between lens and sample surface was investigated.The laser energies were 12 mJ, 16 mJ, 20 mJ, and 24 mJ. All experiments were carried out in an atmospheric environment. The results indicated that the intensity of Si(I) 390.55 nm line firstly rose and then dropped with the increase of lens-to-sample distance. Moreover, the spectral peak intensity with spatial confinement was higher than that without spatial confinement. The enhancement ratio was approximately 2 when laser energy was 24 mJ. 展开更多
关键词 laser-induced breakdown spectroscopy LIBS spatial confinement distance of lens- to-sample signal enhancement
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Interference effect of photoionization of hydrogen atoms by ultra-short and ultra-fast high-frequency chirped pulses 被引量:3
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作者 Ningyue Wang Aihua Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第8期112-118,共7页
The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrodinger equation within length,velocity,and Kramers-Henneberger... The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrodinger equation within length,velocity,and Kramers-Henneberger gauges.Converged results for all gauges for chirp-free pulses agree with the prediction of dynamic interference for ground state hydrogen atoms predicted recently by Jiang and Burgdorfer[Opt.Express 26,19921(2018)].In addition,we investigated photoelectron spectra of hydrogen atoms by chirped laser pulses,and showed that dynamic interference effect will be weaken for pulses with increasing linear chirp.Our numerical results can be understood and discussed in terms of an interplay of photoelectron wavepackets from first and second halves of laser enevelop,including the ac Stark energy level shift of the photoelectron final state and atomic stabilization effect at ultra-high intensities. 展开更多
关键词 dynamic INTERFERENCE super-intense laser CHIRPED pulses
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Time-resolved spectroscopy of femtosecond laser-induced Cu plasma with spark discharge 被引量:3
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作者 Qiuyun WANG Anmin CHEN +5 位作者 Wanpeng XU Dan ZHANG Ying WANG Suyu LI Yuanfei JIANG Mingxing JIN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第6期140-146,共7页
The combination of spark discharge and laser-induced breakdown spectroscopy (LIBS) is called spark discharge assisted LIBS.It works under laser-plasma triggered spark discharge mode,and shows its ability to enhance sp... The combination of spark discharge and laser-induced breakdown spectroscopy (LIBS) is called spark discharge assisted LIBS.It works under laser-plasma triggered spark discharge mode,and shows its ability to enhance spectral emission intensity.This work uses a femtosecond laser as the light souuce,since femtosecond laser has many advantages in laser-induced plasma compared with nanosecond laser,meanwhile,the study on femtosecond LIBS with spark discharge is rare.Time-resolved spectroscopy of spark discharge assisted femtosecond LIBS was investigated under different discharge voltages and laser energies.The results showed that the spectral intensity was significantly enhanced by using spark discharge compared with LIBS alone.And,the spectral emission intensity using spark discharge assisted LIBS increased with the increase in the laser energy.In addition,at low laser energy,there was an obvious delay on the discharge time compared with high laser energy,and the discharge time with positive voltage was different from that with negative voltage. 展开更多
关键词 LASER-INDUCED BREAKDOWN SPECTROSCOPY FEMTOSECOND laser spark DISCHARGE emission enhancement
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Effects of 5f-elements on electronic structures and spectroscopic properties of gold superatom model 被引量:3
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作者 高阳 王志刚 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第8期1-9,共9页
5f-elements encaged in a gold superatomic cluster are capable of giving rise to unique optical properties due to their hyperactive valence electrons and great radial components of 5f/6d orbitals. Herein, we review our... 5f-elements encaged in a gold superatomic cluster are capable of giving rise to unique optical properties due to their hyperactive valence electrons and great radial components of 5f/6d orbitals. Herein, we review our first-principles studies on electronic structures and spectroscopic properties of a series of actinide-embedded gold superatomic clusters with different dimensions. The three-dimensional(3D) and two-dimensional(2D) superatom clusters possess the 18-electron configuration of 1S21P61D10 and 10-electron configuration of 1S21P41D4, respectively. Importantly, their electronic absorption spectra can also be effectively explained by the superatom orbitals. Specifically, the charge transfer(CT) transitions involved in surface-enhance Raman spectroscopy(SERS) spectra for 3D and 2D structures are both from the filled 1D orbitals, providing the enhancement factors of the order of ~ 10^4 at 488 nm and ~ 10^5 at 456 nm, respectively. This work implies that the superatomic orbital transitions involved in 5f-elements can not only lead to a remarkable spectroscopic performance, but also a new direction for optical design in the future. 展开更多
关键词 5f-electrons ds-electrons superatom FIRST-PRINCIPLES
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Effect of cylindrical cavity height on laserinduced breakdown spectroscopy with spatial confinement 被引量:3
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作者 邵俊峰 王挺峰 +2 位作者 郭劲 陈安民 金明星 《Plasma Science and Technology》 SCIE EI CAS CSCD 2017年第2期89-94,共6页
In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy (LIBS). The emission intensity with the spatial confineme... In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy (LIBS). The emission intensity with the spatial confinement is dependent on the height of the confinement cavity. It is found that, by selecting the appropriate height of cylindrical cavity, the signal enhancement can be significantly increased. At the cylindrical cavity (diameter = 2 mm) with a height of 6 mm, the enhancement ratio has the maximum value (approximately 8.3), and the value of the relative standard deviation (RSD) (7.6%) is at a minimum, the repeatability of LIBS signal is best. The results indicate that the height of confinement cavity is very important for LIBS technique to reduce the limit of detection and improve the precision. 展开更多
关键词 LIBS spatial confinement cavity height signal enhancement
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Theoretical prediction of energy dependence for D+BrO→DBr+O reaction:The rate constant and product rotational polarization 被引量:1
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作者 张莹莹 解廷献 +2 位作者 李泽瑞 石英 金明星 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第3期412-417,共6页
A quasi-classical trajectory(QCT) calculation is used to investigate the vector and scalar properties of the D + Br O → DBr + O reaction based on an ab initio potential energy surface(X1A state) with collision ... A quasi-classical trajectory(QCT) calculation is used to investigate the vector and scalar properties of the D + Br O → DBr + O reaction based on an ab initio potential energy surface(X1A state) with collision energy ranging from 0.1 kcal/mol to 6 kcal/mol. The reaction probability, the cross section, and the rate constant are studied. The probability and the cross section show decreasing behaviors as the collision energy increases. The distribution of the rate constant indicates that the reaction favorably occurs in a relatively low-temperature region(T 〈 100 K). Meanwhile, three product angular distributions P(θr), P(φr), and P(θr, φr) are presented, which reflect the positive effect on the rotational angular momentum j' polarization of the DBr product molecule. In addition, two of the polarization-dependent generalized differential cross sections(PDDCSs), PDDCS00 and PDDCS20, are computed as well. Our results demonstrate that both vector and scalar properties have strong energy dependence. 展开更多
关键词 quasi-classical trajectory cross section rate constant product angular distributions
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Influence of target temperature on femtosecond laser-ablated brass plasma spectroscopy 被引量:1
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作者 Junfeng SHAO Jin GUO +2 位作者 Qiuyun WANG Anmin CHEN Mingxing JIN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第7期4-10,共7页
Spectral intensity,electron temperature and density of laser-induced plasma(LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy(LIBS).Increasing target temperature is an eas... Spectral intensity,electron temperature and density of laser-induced plasma(LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy(LIBS).Increasing target temperature is an easy and feasible method to improve the sensitivity.In this paper,a brass target in a temperature range from 25℃ to 200℃ was ablated to generate the LIP using femtosecond pulse.Time-resolved spectral emission of the femtosecond LIBS was measured under different target temperatures.The results showed that,compared with the experimental condition of 25℃,the spectral intensity of the femtosecond LIP was enhanced with more temperature target.In addition,the electron temperature and density were calculated by Boltzmann equation and Stark broadening,indicating that the changes in the electron temperature and density of femtosecond LIP with the increase of the target temperature were different from each other.By increasing the target temperature,the electron temperature increased while the electron density decreased.Therefore,in femtosecond LIBS,a hightemperature and low-density plasma with high emission can be generated by increasing the target temperature.The increase in the target temperature can improve the resolution and sensitivity of femtosecond LIBS. 展开更多
关键词 laser-induced breakdown spectroscopy time-resolved spectroscopy emission enhancement femtosecond laser target temperature
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A Precise Description of the Electronic Structures and Spin-Allowed Transition Properties of PF and Its Cation:All-Electron Configuration-Interaction Investigations Including Relativistic Effect 被引量:1
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作者 李奇楠 赵书涛 +3 位作者 张晓美 罗旺 李瑞 闫冰 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第7期42-46,共5页
The electronic structures of PF and PF+ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, a... The electronic structures of PF and PF+ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, and the Davidson correction(q-Q) are also considered. The spectroscopic parameters of bound states are derived by the electronic structures of PF and PF+, which are in good accordance with the measurements. The transition dipole moments of spin-allowed transitions are evaluated, and the radiative lifetimes of several A S states of PF and PF+ are obtained. 展开更多
关键词 A Precise Description of the Electronic Structures and Spin-Allowed Transition Properties of PF and Its Cation:All-Electron Configuration-Interaction Investigations Including Relativistic Effect PF TDM
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Accurate all-electron calculation on the vibrational and rotational spectra of ground states for O2 and its ions
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作者 Qiao-Xia Wang Yu-Min Wang +1 位作者 Ri Ma Bing Yan 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第7期193-197,共5页
The potential energy curves, spectroscopic constants, and low-lying vibration–rotation levels of ground-state O2 and its cation O2+ and anion O2- were calculated with the explicitly correlated multireference configur... The potential energy curves, spectroscopic constants, and low-lying vibration–rotation levels of ground-state O2 and its cation O2+ and anion O2- were calculated with the explicitly correlated multireference configuration interaction method.The zeroth-order reference wavefunction was treated with the complete active space multiconfigurational self-consistent field method, in which the active space was carefully selected, and an additional molecular orbital πu was added into the full valence active space.The electron correlation of the 1s core in the oxygen atom was considered in the computations.The Davidson correction on molecular energy was considered to account for higher electron excitation.The relativistic effects, including the scalar relativistic effect and spin–orbit coupling, were considered in the computation of potential energy curves.These physical effects on the spectroscopic constants were examined.The low-lying levels of vibration–rotation spectra of O2 and its ions were determined based on the computed potential energy curves.Comparisons with available experiments were made and excellent agreement was obtained for the vibrational and rotational parameters.The spectroscopic constants and vibration–rotation spectrum of O2-, which is sparse in experiments, were provided.Our study will shed some light on further theoretical and experimental studies on these simple but important molecular systems. 展开更多
关键词 O2 molecule/molecular ion explicitly correlated MULTIREFERENCE configuration interaction SPECTROSCOPIC constant vibration–rotation spectrum
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Photoelectron imaging of resonance-enhanced multiphoton ionization and above-threshold ionization of ammonia molecules in a strong 800-nm laser pulse
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作者 Le-Le Song Ya-Nan Sun +7 位作者 Yan-Hui Wang Xiao-Chun Wang Lan-Hai He Si-Zuo Luo Wen-Hui Hu Qiu-Nan Tong Da-Jun Ding Fu-Chun Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第6期140-145,共6页
In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photo... In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photoelectron images are detected. The channel switching and above-threshold ionization(ATI) effect are also confirmed. The kinetic energy spectrum(KES) and the photoelectron angular distributions(PADs) are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C^1 A 1(6 + 2 photons process), B^1 E(6 + 2 photons process) and C^1 A 1(7 + 2 photons process), respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high. 展开更多
关键词 PHOTOELECTRON imaging RYDBERG state resonance-enhanced MULTIPHOTON IONIZATION PHOTOELECTRON ANGULAR distribution
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Ultrafast Dynamics of Defect-Assisted Carrier Capture in MoS2 Nanodots Investigated by Transient Absorption Spectroscopy
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作者 Da Ke Lai-zhi Sui +8 位作者 Dun-li Liu Jian-qiu Cui Yun-feng Zhang Qing-yi Li Su-yu Li Yuan-fei Jiang An-min Chen Jun-ling Song Ming-xing Jin 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第3期277-283,367,共8页
MoS2 nanodots are emerging as promising semiconductor materials for optoelectronic devices. However, most of the recent attention is focused on the fabrication of MoS2 nanodots,and the survey for exciton dynamics of M... MoS2 nanodots are emerging as promising semiconductor materials for optoelectronic devices. However, most of the recent attention is focused on the fabrication of MoS2 nanodots,and the survey for exciton dynamics of MoS2 nanodots remains less explored. Herein, we use femtosecond transient absorption spectroscopy to investigate the carrier dynamics of MoS2 nanodots. Our results show that defect-assisted carrier recombination processes are well consistent with the observed dynamics. The photo-excited carriers are captured by defects with at least two different capture rates via Auger scattering. Four processes are deemed to take part in the carrier relaxation. After photoexcitation, carrier cooling occurs instantly within ~0.5 ps. Then most of carriers are fast captured by the defects, and the corresponding time constant increases from ~4.9 ps to ~9.2 ps with increasing pump fluence, which may be interpreted by saturation of the defect states. Next a small quantity of carriers is captured by the other kinds of defects with a relatively slow carrier capture time within ~65 ps.Finally, the remaining small fraction of carriers relaxes via direct interband electron-hole recombination within~1 ns. Our results may lead to deep insight into the fundamentals of carrier dynamics in MoS2 nanodots, paving the way for their further applications. 展开更多
关键词 MOS2 Transient absorption spectroscopy Defect-assisted CARRIER CAPTURE
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Magnetism and piezoelectricity of hexagonal boron nitride with triangular vacancy
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作者 赵路丝 陈春平 +3 位作者 刘林林 于洪侠 陈怡 王晓春 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第1期450-455,共6页
First-principle calculations reveal that the configuration system of hexagonal boron nitride (h-BN) monolayer with triangular vacancy can induce obvious magnetism, contrary to that of the nonmagnetic pristine boron ... First-principle calculations reveal that the configuration system of hexagonal boron nitride (h-BN) monolayer with triangular vacancy can induce obvious magnetism, contrary to that of the nonmagnetic pristine boron nitride monolayer. Interestingly, the h-BN with boron atom vacancy (VB-BN) displays metallic behavior with a total magetic moment being 0.46μB per cell, while the h-BN with nitrogen atom vacancy (VN-BN) presents a half-metallic characteristic with a total magnetic moment being 1.0μB per cell. Remarkably, piezoelectric stress coefficient ell of the VN-BN is about 1.5 times larger than that of pristine h-BN. Furthermore, piezoelectric strain coefficient dll (12.42 μm/V) of the VN-BN is 20 times larger than that of pristine h-BN and also one order of magnitude larger than the value for the h-MoS2 monolayer, which is mainly due to the spin-down electronic state in the VN-BN system. Our study demonstrates that the nitrogen atom vacancies can be an efficient route to tailoring the magnetic and piezoelectric properties of h-BN monolayer, which have promising performances for potential applications in nano-electromechanical systems (NEMS) and nanoscale electronics devices. 展开更多
关键词 FIRST-PRINCIPLE MAGNETISM PIEZOELECTRIC nano-electromechanical systems
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Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene in strong IR and UV laser fields
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作者 张军峰 吕航 +3 位作者 左万龙 徐海峰 金明星 丁大军 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第11期212-216,共5页
Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene are studied in linearly polarized 50-fs, 800-nm and 400-nm strong laser fields using a time-of-flight mass spectrometer. It is shown that at ... Ionizations and fragmentations of benzene, methylbenzene, and chlorobenzene are studied in linearly polarized 50-fs, 800-nm and 400-nm strong laser fields using a time-of-flight mass spectrometer. It is shown that at low laser intensity, the parent ions are dominant for any one of the molecules in an 800-nm strong laser field, while extensive fragmentation is observed in a 400-nm laser field, which can be understood by the resonant photon absorption of molecular cations. The ratio of the yield of the parent ion to the yield of the total ion for each molecule is measured as a function of laser intensity in a range from 1.0 × 1013 W/cm2 to 4.0 × 1014 W/cm2, in either the 800-nm or 400-nm laser field. The results show that the fragmentation of the aromatic molecules increases significantly as the laser intensity is increased. Possible mechanisms for fragmentation in strong laser fields are discussed. Finally, the saturation intensity of ionization of the titled molecules is also determined. 展开更多
关键词 strong field ionization FRAGMENTATION BENZENE substitute benzene
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Field-free orientation of diatomic molecule via the linearly polarized resonant pulses
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作者 李苏宇 郭福明 +2 位作者 王俊 杨玉军 金明星 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第10期213-217,共5页
We propose a scheme to coherently control the field-free orientation of NO molecule whose rotational temperature is above 0 K. It is found that the maximum molecular orientation is affected by two factors: one is the... We propose a scheme to coherently control the field-free orientation of NO molecule whose rotational temperature is above 0 K. It is found that the maximum molecular orientation is affected by two factors: one is the sum of the population of M = 0 rotational states and the other is their distribution, however, their distribution plays a much more significant role in molecular orientation than the sum of their population. By adopting a series of linearly polarized pulses resonant with the rotational states, the distribution of M = 0 rotational states is well rearranged. Though the number of pulses used is small, a relatively high orientation degree can be obtained. This scheme provides a promising approach to the achievement of a good orientation effect. 展开更多
关键词 ORIENTATION diatomic molecule linearly polarized pulses coherent control
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Accurate calculation of the potential energy curve and spectroscopic parameters of X^2Σ^+ state of ^(12)Mg^1H
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作者 伍冬兰 谭彬 +2 位作者 谢安东 闫冰 丁大军 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第4期170-174,共5页
High level calculations on the ground state of 12Mg1H molecule have been performed using multi-reference configuration interaction (MRCI) method with the Davidson modification. The core-valence correlation and scala... High level calculations on the ground state of 12Mg1H molecule have been performed using multi-reference configuration interaction (MRCI) method with the Davidson modification. The core-valence correlation and scalar relativistic corrections are included into the present calculations at the same time. The potential energy curve (PEC) of the ground state, all of the vibrational levels and spectroscopic parameters are fitted. The results show that the levels and spectroscopic parameters are in good agreement with the available experimental data. The analytical potential energy function (APEF) is also deduced from the calculated PEC using the Murrell-Sorbie (M-S) potential function. The present results can provide a helpful reference for the future spectroscopic experiments or dynamical calculations of the molecule. 展开更多
关键词 multi-reference configuration interaction potential energy curve analytical potential energy function spectroscopic parameters
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