• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    High-order harmonic generation of ZnO crystals in chirped and static electric fields

    2024-01-25 07:27:46LingYuZhang張玲玉YongLinHe何永林ZhuoXuanXie謝卓璇FangYanGao高芳艷QingYunXu徐清蕓XinLeiGe葛鑫磊XiangYiLuo羅香怡andJingGuo郭靜
    Chinese Physics B 2024年1期
    關鍵詞:郭靜

    Ling-Yu Zhang(張玲玉), Yong-Lin He(何永林), Zhuo-Xuan Xie(謝卓璇), Fang-Yan Gao(高芳艷),Qing-Yun Xu(徐清蕓), Xin-Lei Ge(葛鑫磊), Xiang-Yi Luo(羅香怡), and Jing Guo(郭靜),?

    1Institute of Atomic and Molecular Physics,Jilin University,Changchun 130012,China

    2School of Physics and Electromechanical Engineering,Hexi University,Zhangye 734000,China

    3Institute of Theoretical Physics,Hexi University,Zhangye 734000,China

    4College of Physical Science and Technology,Bohai University,Jinzhou 121013,China

    5College of Physics and Electronic Information,Baicheng Normal University,Baicheng 137000,China

    Keywords: high-order harmonic generation, the semiconductor Bloch equation, k-resolved inter-band harmonic spectrum,four-step semiclassical model

    1.Introduction

    High-order harmonics generation(HHG)driven by laser not only is a special nonlinear optical phenomenon, but also has become an important way to make extreme UV or soft xray band light source and desktop attosecond light source in the laboratory,[1,2]which provides a feasible scheme for synthesizing attosecond pulses to observe the internal electron dynamics of atoms and molecules,and also makes it possible to further explore and control microscopic particles.The physical mechanism of HHG is mainly given by the semi-classical three-step model proposed by Corkum in 1993.[3]In 2019,Luet al.[4]proposed a four-step model to study HHG in solids,which can be explained as follows: (i) Electrons in the valence band are accelerated by a laser field.(ii)Tunneling excitation occurs at the minimum band gap.(iii) Subsequently,electron and hole pairs accelerate within the band.(iv) Finally,electron and hole recombine and emit harmonic photons with band-gap energy.Compared with the three-step model,the four-step model mainly has a pre-acceleration process.In 2020,Songet al.[5]studied ZnO driven by multi-color pulses to enhance HHG,and proved the occurrence of intra-band preacceleration,which confirmed the proposed four-step model of HHG from semiconductor.

    Based on the research of high harmonics in gas, the description of the harmonic radiation process in solids is gradually perfected,and compared with the electron dynamics process in gas, there is a bit of differences for ultrafast electron dynamics in solids.In order to improve the harmonic efficiency and to extend the high-order harmonic spectrum, researchers have taken many methods in research of high-order harmonic generation from gas,such as using the chirp to control the laser waveform and controlling the dynamics of HHG.Spatially inhomogeneous fields,[6]two-color field,[7]and its combination with chirped pulse,[8,9]as well as the combination of static electric field and chirp[9,10]are used to extend the cutoff energy.For example, Mohebbi[11]used the combination of chirped laser pulse, non-chirped laser pulse and static electric field to drive helium atoms to enhance HHG,and then synthesized a clean 38 as isolated attosecond pulse.Liuet al.[12]introduced a two-color chirped pulse to extend the platform of HHG, and also added a controlled IR or UV pulse to improve the harmonic efficiency.Koushkiet al.[9]showed that adding a static electric field to a two-color chirped laser field can significantly increase the harmonic cutoff and obtain pulses with a minimum duration of 21 as.

    However,the emission of high harmonics driven by combined fields in solids needs to be further studied.Since the HHG process in solids is more complicated than that in atoms, which is due to the coincident movement of electrons and holes in the conduction band and valence band in solids,[13–17]the interference between high harmonics emitted by different channels,[18]or between inter-band and intra-band currents.[19]Based on this,we study the HHG of the combined field along theΓ–Mdirection of the ZnO crystal by solving the SBEs.The characteristics of harmonic spectra are analyzed based on the recollision model.Moreover,k-resolved inter-band harmonic spectra are also given.The incomplete X-structure of the inter-band harmonic spectrum can be analyzed by the four-step model.

    In the rest of this paper,we present the theoretical method used here in Section 2.The calculation results and discussion are given in Section 3.Finally, the conclusions are given in Section 4.Atomic units are used throughout the text unless stated otherwise.

    2.Theoretical method

    HHG in solids can be investigated by many theoretical methods, such as the time-dependent Schr¨odinger equation(TDSE),[20–25]the time-dependent density functional theory (TDDFT),[26–31]and the semiconductor Bloch equation(SBE).[32–38]In this paper, we use SBEs to simulate HHG in solids:[14,15,39,40]

    Our simulation is based on a two-band model, including a valence band and a conduction band.Therefore in Eq.(1)nm=v,crepresents band population, v and c refer to valence band and conduction band, respectively, andπmm'(K,t) represents the quantum coherence between valence band and conduction band.?mm'(K,t) =E(t)·dmm'[K+A(t)] is the Rabi frequency, whereE(t)is the electric field anddmm'[K+A(t)] is the momentumdependent transition dipole moment of the crystal between the two bands.Here, eiSmm'is the phase term, andSmm'(K,t)=t?∞{εm[K+A(t')]?εm'[K+A(t')]}dt'is the classical action,εmandεm'refer to band energy,andT2is the dephasing time.According to Bloch’s acceleration theorem,crystal momentumK(t)=k ?A(t) is in a moving coordinate system,K(t)is the time-dependent momentum under the laser field,kis the initial momentum,is the vector potential of the laser field.In the semiconductor Bloch equations,we are usingK+A(t)to denotek,andA(t)depends ont,so the variables are represented only byKandt.The polarization, which represents the polarizability between two energy bands,is defined as[14]

    The intra-band current and the inter-band current are expressed as[14]

    whereυm(k)=?kεm(k)denotes the velocity of valence band(m=v) and conduction band (m=c).The intra-band and inter-band harmonic spectra are obtained by taking the Fourier transform of the intra-band current and inter-band current after derivation of time, respectively, and the total harmonic spectrum is obtained from the total currents:

    The one-dimensional SBE is adopted for simulation,and laser field can be expressed as

    wheref(t)is a Gaussian type envelope,τis the full width at half maximum (FWHM).E0,ω0, and?0are the peak value,frequency,and carrier envelope phase of electric field,respectively;αis the chirped parameter;βis the amplitude ratio between the static electric field and the fundamental frequency field(E0).The polarization direction of the laser pulse is along theΓ–Mdirection of ZnO crystal.

    In solid, electrons (holes) move according to Newtonian equations:, where ˉhkis the momentum.The details are as follows:

    The intraband current and interband current can be calculated by the solid strong field approximation formula[14]

    In the solid strong field approximation theory,the contribution of interband polarization near the saddle point dominates.The phase term in the interband current is

    At the saddle point,the first derivative of the phase term with respect to the three variablesk,t',tis equal to 0,and the three saddle point equations can be given as follows:

    Three saddle point equations are given,and three saddle point conditions can be obtained: (i)k(t) =k0+A(t)?A(t')denotes the electron tunneling from the minimum band gapk0at timet', which is called the tunneling condition.(ii)Δxe?Δxh=0 represents the recollision of electrons and holes in real space, and the harmonic photons are emitted when the collision occurs,which is called the recollision condition.(iii)ω=εc[k(t)]?εv[k(t)] indicates that the energy of the harmonic photon radiated upon recollision is equal to the instantaneous band gap when the electron–hole pair recombines,which is called the energy conservation condition.If only(i)and(ii)are considered, thek-space quasi-classical model can be obtained.If (i), (ii), and (iii) are considered at the same time, the real space recollision model can be obtained.The real space recollision model holds that electrons undergo three processes,namely tunneling ionization,electron acceleration,and electron hole pair recombination,and finally we can realize harmonic radiation.[41]

    3.Results and discussion

    In our calculations, we use fundamental pulse (α=0,β=0) withE0= 0.0037 a.u.(I= 0.48 TW/cm2),λ=3200 nm,ω0=0.0142 a.u.,?0=0, andτ=10.3 fs orτ=64 fs.The chirp parameterαis selected to be 3×10?6and 5×10?6.The amplitude ratio between the static electric field and the fundamental frequency field,β, is chosen as 0.2 and 0.4.Although the static field ofβ=0.4 is slightly higher, it may be difficult to realize experimentally, but low-frequency laser field(such as CO2laser)can be used instead.[10,42,43]The total duration is taken as 4 o.c.and 25 o.c.(o.c.:optical cycle)in the simulation.Firstly, the structure top view of ZnO and the valence band and conduction band are shown in Figs.1(a)and 1(b).Figure 1(a)shows the top view of ZnO in real space,which presents a hexagonal honeycomb structure.We focus on the band structure along theΓ–Mdirection of the crystal,as shown in Fig.1(b),including a valence band and a conduction band,marked by solid line and dashed line,respectively.In order to compare the influence of chirp parameters and amplitude ratios of static electric field to fundamental frequency pulse on HHG, the harmonics under different parameters or amplitude ratios of fields are shown in Fig.2.

    Fig.1.(a) Top view of wurtzite ZnO with the Zn (the blue balls) and O(the orange balls)atoms.(b)Energy band structure of ZnO along the Γ–M direction, considering the two-band model with a valence band and a conduction band.

    It can be seen from Figs.2(a1) and 2(b1) that the harmonics drop rapidly from 0 to the 7th order,and the intensity of the harmonics is almost constant from 9th to 29th order,about 10?7orders of magnitude,and the cutoff is of the 29th order.With the introduction of chirped pulse with 4 o.c.and 25 o.c.in Figs.2(a1) and 2(b1), we can see that harmonic modulation is obvious.Moreover,the existence of static electric field can improve the harmonic efficiency, as shown in Figs.2(a2) and 2(b2).When the combination of single-color chirp-free pulse and static electric field is considered(α=0,β/=0), the modulation in the harmonic platform is reduced,and the interference structure of harmonics below the 7th order is obvious.Driven by the combination of single-color chirped pulse and static electric field,we can obtain relatively continuous harmonic spectrum.Compared with the 4-period case,the harmonic spectrum presents similar characteristic with the 25-period case.Furthermore, we also consider the influence of the combined pulse of chirped pulse and static electric field on HHG, and find that the harmonic intensity in Figs.2(a3)and 2(b3) is roughly 1 or 2 orders of magnitude higher than that in Figs.2(a1) and 2(b1).However, compared to HHG driven by the combination of single-color chirp-free pulse and static electric field in Figs.2(a2)and 2(b2),the modulation of the harmonic driven by the combination of chirped pulse and static electric field is more obvious [as shown in Figs.2(a3)and 2(b3)].

    The harmonics are optimized.By changing the laser intensity of the single-color chirp-free field, the peak intensity of the electric field reaches the peak intensity of the combination of the single-color field and the static electric field(E0=0.0044 a.u.,E01=0.0051 a.u.),and calculating the harmonic spectrum in Figs.3(a) and 3(b), we find that the harmonic intensity is improved.When the static electric field is added, the harmonic efficiency is indeed improved and relatively continuous harmonic spectra are obtained with the 4-period and 25-period cases,and with the 4-period case the harmonics are smoother.Moreover, by changing the carrier envelope phase(CEP)of the single-color chirp-free laser pulse,harmonics are seldom changed,which is not shown.

    The harmonic spectrum is calculated when the amplitude ratio of the static electric field to the fundamental laser field is negative (β=?0.2,β=?0.4), as shown in Fig.4.We can find that the harmonic efficiency is improved no matter whetherβis positive or negative.However, when positive values are taken, relatively continuous harmonics can be obtained.

    Fig.2.HHG from ZnO driven by different fields in 4-period and 25-period cases.(a1)–(a3)HHG in the single-color chirped pulse(α =3×10?6,5×10?6),the combination of single-color chirp-free pulse and static electric field(β =0,0.2,0.4),and the combination of single-color chirped pulse and static electric field with duration of 4 optical cycles.(b1)–(b3)Results with pulse duration of 25 optical cycles.Other laser parameters are the same as those in(a1)–(a3).

    Fig.3.The total harmonic spectrum under the laser field with(a)4 o.c.and(b)25 o.c.at different laser intensities.

    In the case of HHG in gas, the introduction of chirp pulse and static electric field can greatly improve the cutoff frequency,[11,44,45]and enhance the harmonic efficiency.[46,47]However, in our work, the intensity of the harmonic plateau is improved, but the cutoff cannot be extended.This phenomenon is quite different from the results of HHG in gas.In order to analyze the internal reasons for these differences,we first give the profile and vector potential of each field,and the time-dependent electron population in the conduction band.For the convenience of the analysis, we only consider the 4-period case.

    Figure 5 shows the electric field profiles of different laser fields,the vector potential,and the electron population of conduction band.We can see that with static electric field, the ionization probability of electron is greater than that of singlecolor chirp free pulse and chirped pulse.The fast excitation of electrons is still related to the peak value of electric field and corresponding vector potential.When the electric field reaches its peak value and the value of the corresponding vector potential is not 0, the electron is rapidly excited to the conduction band [see Fig.5(b)].Because the addition of the static electric field breaks the symmetry of the field in the adjacent half period, the maximum peak value of the laser field increases,so that the probability of electron ionization increases [see Figs.5(a)and 5(c)].

    In order to clearly understand the physical mechanism of the large difference between the harmonic spectra in ZnO and the gas, we present the time-frequency of the harmonics in ZnO.Based on the change of the field waveform and the rapid excitation rate of electrons at the peak value of the electric field, the harmonic spectrum in Fig.2 is further analyzed in combination with the time frequency, as shown in Fig.6.The harmonics mainly contribute from short trajectories by a single-color chirp free pulse in Fig.6(a).By introducing the chirped pulse,the contribution of long quantum trajectories is enhanced,leading to the appearance of modulation in the harmonics, and the interference structure is evident in Fig.6(b),which is consistent with the harmonic spectrum in Fig.2(a1).Similar results can be obtained in the case of 25 o.c.

    Fig.5.(a)Electric field profiles of single-color chirp free pulse,singlecolor chirped pulse, combination of single-color chirp free pulse and static electric field, and combination of single-color chirped pulse and static electric field.(b) The vector potential corresponding to (a).(c) Evolution of electron population in conduction band as a function of time in each field.

    In the case of 4 o.c., the main contribution of harmonics is from short trajectories when ZnO is driven by single-color chirp-free pulse and there are mainly two peaks in the timefrequency distribution of harmonics.Some electrons are excited to the conduction band att=?0.5 o.c.and return to the valence band aroundt=0 o.c., radiating harmonics, corresponding to harmonic peaks of the time-frequency distribution aroundt=0 o.c.The harmonic peak aroundt=0.5 o.c.mainly stems from the fast excitation of electrons att=0 o.c.when the pulse reaches its peak.The time frequency agrees well with the classical recollision trajectory in Fig.6.In Fig.6(b), compared with the chirp free pulse, the amplitude and frequency of the chirp pulse are smaller, and the probability of electron ionization is lower att <0 o.c.As a result,the probability of electron returning to valence band and recombination with hole aftert=0 o.c.is reduced, and the harmonic signal of radiation is weakened.Corresponding to Figs.2(a1) and 2(b1), the intensity of the high-energy region of harmonics decreases slightly.However,the strong signal of harmonic peak aroundt=0.5 o.c.is mainly due to tunneling excitation of electrons att=0 o.c.,when the laser field reaches its peak, and the probability of electron ionization reaches its maximum.Att=0.5 o.c., the amplitude and instantaneous frequency of the chirp field increase, then the possibility of recollision of electron–hole pairs increases, and the emitted harmonic signal is enhanced,which leads to a slightly increase in the intensity of the harmonic plateau as shown in Figs.2(a1)and 2(b1).

    In Figs.6(c) and 6(d), in the presence of static electric field, for low order harmonics, both long and short quantum trajectories have important contribution,corresponding to strong harmonic spectrum modulation.[40]For the part larger than 17th order, the short trajectory makes the great contribution to HHG,and the long trajectory is largely suppressed,corresponding to relatively continuous harmonic spectrum in Figs.2(a2)and 2(a3)and Figs.2(b2)and 2(b3).

    The total harmonic spectrum is mainly contributed by the inter-band harmonic spectrum,so we also givek-resolved profile of the inter-band harmonic spectra analyzed by a four-step model.

    Fig.7.The k-resolved profile of inter-band harmonic spectra generation by different fields.(a1)–(d1)The k-resolved profile of interband harmonic spectra by single-color chirp-free pulse (α =0, β =0), single-color chirped pulse (α =5×10?6), the combination of single-color chirp-free pulse and static electric field (β =0.2), and the combination field of single-color chirped pulse and static electric field(α =5×10?6,β =0.2)with the duration of 4 o.c.(a2)–(d2)Results with a pulse duration of 25 o.c.Other parameters are the same as those in(a1)–(d1).

    Figures 7(a1)–7(d1)and 7(a2)–7(d2)show thek-resolved inter-band harmonic spectra for a single-color chirp free pulse,a single-color chirped pulse, a combined field of single-color chirp free pulse and static electric field,and a combined field of single-color chirped pulse and static electric field with 4 o.c.and 25 o.c., respectively.In the case of 4 o.c., some electrons whose initial momentum is not 0 move to the top of the valence band driven by the laser field, and this is called the pre-acceleration process.The electrons that reach the top of the valence band will be excited to the bottom of the conduction band more easily, and the electrons excited to the conduction band and the holes in the valence band will undergo Bloch oscillation together in the laser field.Since the peak values of laser pulses in the adjacent half periods are different, the electrons moving on the conduction band will move at different distances on both sides of theΓpoint.In adjacent half-cycle, when the peak value of pulse is small, electron–hole pairs are driven to move neark= 0, while the peak value of pulse is large,electron–hole pairs are driven to move far away fromk= 0, resulting in incomplete X-type structures ofk-resolved inter-band harmonic spectra in Figs.7(a1)–7(d1).In the case of 25-period single-color chirp free pulse as shown in Fig.7(a2) and single-color chirped pulse as shown in Fig.7(b2),thek-resolved inter-band harmonics presents the X-type structure.Under the chirped pulse,the inter-band harmonic spectrum ink-space is asymmetric with respect tok=0.After the static electric field is added,k-resolved inter-band harmonic spectrum has a periodic incomplete X-type intensity distribution structure along thekdirection[see Figs.7(c2)and 7(d2)].Due to the introduction of 25-period pulses,k-resolved inter-band harmonic spectrum shows a periodic sloping structure as shown in Figs.7(c1) and 7(c2) and Figs.7(d1) and 7(d2).

    Incomplete X-typek-resolved profile of interband harmonic spectrum can be explained by the four-step model.In Figs.8(a1)–8(a3),we can see that the electron tunnels from the top of the valence band att=0 o.c.,and then presents Bloch oscillation in the conduction band.Att=0.25 o.c., vector potential reaches its peaks at?0.2573 a.u., and the electron moves tok(t) =?0.2573 a.u.Att= 0.55 o.c., the vector potential is approximately 0 and the electron returns to the bottom of the conduction band.Att=0.75 o.c., the vector potential reaches peak of 0.0988 a.u., and the electron also moves to thek(t)=0.0988 a.u.In addition,the electrons have a pre-acceleration process in the valence band before tunneling.Therefore,in the case of 4 o.c.,thek-resolved inter-band harmonics finally present an incomplete X-shaped structure as shown in Fig.7(a1).In the 4-period single-color chirped field(see Figs.8(b1)–8(b3)), the asymmetric X-type structure can also be analyzed by the motion of electrons ink-space.Beforet=0.026 o.c., the electron near the top of the valence band goes through a pre-acceleration process tok=0 a.u.and then the electrons are excited att=0.026 o.c.Att=0.24 o.c.,the vector potential reaches a peak of?0.2088 a.u.and the electron moves tok(t)=?0.2088 a.u.The electron then accelerates.The vector potential is 0 and the electron returns to the bottom of the conduction band att=0.48 o.c.Att=0.68 o.c.,the vector potential reaches another peak of 0.1197 a.u., and the electron also moves to thek(t)=0.1197 a.u.The velocity of the electron decreases to 0 and returns to the lowest point of the conduction band, and then reaches the bottom of the conduction band att=1 o.c.

    In the presence of static electric field,the asymmetric motion of electrons with the change of laser field and vector potential can also be analyzed.Because the static electric field greatly breaks the symmetry of the laser field,k-resolved interband harmonic spectrum only reflects a part of the X-type structure.

    In order to visualize how the laser field affects the electron trajectory, we present the population of transient conduction band.In the 4-period case [see Figs.9(a1)–9(d1)], the electron Bloch oscillation is small, while in the 25-period case,the oscillation is significant [see Figs.9(a2)–9(d2)], and the electron Bloch oscillation is much stronger when the chirped pulse is introduced in Figs.9(b1) and 9(b2) and Figs.9(d1)and 9(d2).Introducing the static electric field, the region reflecting the electrons oscillating is wider, and electrons cross the edge of the first Brillouin zone and experience a Bragg reflection, superimposing the Bloch oscillations[15,24,35,48,49]in the band[see Figs.9(c1)and 9(c2)and Figs.9(d1)and 9(d2)],so that the radiation of multi-channel harmonics occurs,which plays an important role in promoting the harmonic efficiency.Thek-resolved inter-band harmonics in Figs.7(c1)and 7(c2)and Figs.7(d1)and 7(d2)show a periodic slope structure.

    Fig.8.The electric field and vector potential of [(a1), (a2)] single-color chirp-free pulse and[(b1), (b2)] single-color chirped pulse in single cycle.Schematic diagram of the motion of the electron driven by(a3)a single-color chirp-free pulse and(b3)a single-color chirped pulse in k-space.

    Fig.9.The time-dependent population of conduction band by laser pulse with(a1)–(d1)4 o.c.and(a2)–(d2)25 o.c.

    In Figs.9(a1)–9(d1), in the 4-period case, it can be seen that the asymmetry of the electron oscillation ink-space is consistent with the asymmetry of the electron motion analyzed in Fig.8.Electrons travel longer distances along the negative half axis and shorter distances along the positive half axis of the crystal momentum ink-space.This also corresponds to the X-type structure with asymmetrick-resolved inter-band harmonic spectra in Figs.7(a1)–7(d1).However, in the case of 25-period [see Figs.9(a2) and 9(b2)], due to the presence of the pre-acceleration process and the conservation of energy,the correspondingk-resolved inter-band harmonic spectrum shows a relatively symmetric X-type structure[see Figs.7(a2)and 7(b2)].

    4.Conclusions

    We have studied HHG in ZnO crystals under chirped field and static electric field with 4 o.c.and 25 o.c.In the singlecolor chirped laser field,the harmonic cutoff does not extend,but the interference structure is enhanced.In the presence of the static electric field, the harmonic cutoff also remains unchanged, but the harmonic efficiency is improved.The obvious interference structure of harmonics originates from the interference between short and long trajectories,while the continuous harmonics larger than the 17th order in the static electric field are mainly contributed by the short trajectories.By analyzing the motion of electrons inkspace, we explain the incomplete X-type structure of the harmonic spectrum in the asymmetric chirped pulse and static electric field.By singlecolor chirp-free pulses with 25 cycles,k-resolved inter-band harmonic spectrum exhibits a complete X-shaped structure,which reflects the energy conservation and pre-acceleration process.Because the two peak values of the laser field in adjacent half periods have different sizes, resulting in different movement distances of electrons on both sides of theΓpoint,thek-resolved inter-band harmonic spectrum presents an incomplete X-type intensity distribution structure.At the same time,we also explain the existence of the pre-acceleration process.In the presence of the static electric field,electrons cross the first BZ and experience a Bragg reflection,as well as a superposition of oscillation in the conduction band, thus resulting in the radiation of multi-channel harmonics.In addition,time-dependent conduction band population is given,which is consistent with the electron motion in the conduction band.

    Acknowledgments

    This work was supported by the Natural Science Foundation of Jilin Province (Grant No.20220101010JC) and the National Natural Science Foundation of China (Grant No.12074146).

    猜你喜歡
    郭靜
    Photoelectron momentum distributions of Ne and Xe dimers in counter-rotating circularly polarized laser fields
    Exploration of magnetic field generation of by direct ionization and coherent resonant excitation?
    Molecular photoelectron momentum and angular distributions of N2 molecules by ultrashort attosecond laser pulses*
    Ultrafast photoionization of ions and molecules by orthogonally polarized intense laser pulses: Effects of the time delay*
    Helicity of harmonic generation and attosecond polarization with bichromatic circularly polarized laser fields?
    Dependence of photoelectron-momentum distribution of H+2 moleculeon orientation angleand laser ellipticity*
    The Strategy on Starbucks’Brand Building
    智富時代(2018年5期)2018-07-18 17:52:04
    “溫柔的綁架”,北漂女追巨款淪為冷酷兇手
    女士(2016年1期)2016-07-05 07:41:45
    黑丝袜美女国产一区| 色精品久久人妻99蜜桃| 日本色播在线视频| 欧美国产精品一级二级三级| a级毛片黄视频| 十八禁高潮呻吟视频| 国产欧美日韩一区二区三 | 波野结衣二区三区在线| 嫁个100分男人电影在线观看 | 欧美黑人精品巨大| 香蕉丝袜av| 操出白浆在线播放| 中国国产av一级| a 毛片基地| 天天躁狠狠躁夜夜躁狠狠躁| 夫妻性生交免费视频一级片| 18禁黄网站禁片午夜丰满| 亚洲情色 制服丝袜| 亚洲欧美精品综合一区二区三区| 女人高潮潮喷娇喘18禁视频| 国产三级黄色录像| 久久毛片免费看一区二区三区| 国产爽快片一区二区三区| 嫩草影视91久久| 自线自在国产av| 18禁观看日本| av线在线观看网站| 亚洲国产毛片av蜜桃av| videos熟女内射| 一级黄片播放器| 国产精品熟女久久久久浪| 一二三四在线观看免费中文在| 国产黄色视频一区二区在线观看| 国产精品久久久久久精品电影小说| 国产老妇伦熟女老妇高清| 国产亚洲av高清不卡| 午夜精品国产一区二区电影| 国产一区有黄有色的免费视频| 日韩 欧美 亚洲 中文字幕| 捣出白浆h1v1| 亚洲av欧美aⅴ国产| 久9热在线精品视频| 午夜av观看不卡| 波多野结衣一区麻豆| 美女大奶头黄色视频| 男人爽女人下面视频在线观看| 一区二区三区四区激情视频| 永久免费av网站大全| 欧美在线一区亚洲| 亚洲人成电影观看| 操出白浆在线播放| 国产亚洲午夜精品一区二区久久| 国产高清国产精品国产三级| 大片免费播放器 马上看| 亚洲国产精品成人久久小说| 亚洲av综合色区一区| 天天躁狠狠躁夜夜躁狠狠躁| 在线精品无人区一区二区三| 久久人妻熟女aⅴ| 中国美女看黄片| 日本vs欧美在线观看视频| 亚洲情色 制服丝袜| 五月天丁香电影| 亚洲欧美一区二区三区国产| 好男人视频免费观看在线| 欧美精品啪啪一区二区三区 | www.精华液| 中国国产av一级| 国产成人啪精品午夜网站| 国产精品 欧美亚洲| 黄色怎么调成土黄色| 久久精品国产综合久久久| 亚洲 欧美一区二区三区| 亚洲国产最新在线播放| 欧美日韩精品网址| 亚洲专区中文字幕在线| 日韩电影二区| 免费少妇av软件| 男女之事视频高清在线观看 | a 毛片基地| 国产精品一二三区在线看| 亚洲精品第二区| 涩涩av久久男人的天堂| 19禁男女啪啪无遮挡网站| 国产伦人伦偷精品视频| 在线天堂中文资源库| 看十八女毛片水多多多| www.av在线官网国产| 国产av精品麻豆| 久久人妻福利社区极品人妻图片 | 成年女人毛片免费观看观看9 | 精品一区二区三区av网在线观看 | 少妇粗大呻吟视频| 国产爽快片一区二区三区| 亚洲五月色婷婷综合| 亚洲国产精品国产精品| 丝瓜视频免费看黄片| 亚洲图色成人| 亚洲国产精品国产精品| 无遮挡黄片免费观看| 中国国产av一级| 久久青草综合色| 色婷婷久久久亚洲欧美| 纯流量卡能插随身wifi吗| av在线app专区| 两个人免费观看高清视频| 男女无遮挡免费网站观看| 亚洲男人天堂网一区| 老鸭窝网址在线观看| 国产精品一国产av| www.熟女人妻精品国产| 人妻人人澡人人爽人人| 国产精品一区二区精品视频观看| 天堂8中文在线网| 国产精品欧美亚洲77777| 交换朋友夫妻互换小说| 日韩大码丰满熟妇| 国产成人啪精品午夜网站| 亚洲专区国产一区二区| 亚洲精品久久成人aⅴ小说| 欧美精品人与动牲交sv欧美| 一区二区av电影网| 国精品久久久久久国模美| 婷婷色综合www| 伊人久久大香线蕉亚洲五| 国产欧美日韩一区二区三 | 日韩大片免费观看网站| 国产精品三级大全| 色婷婷久久久亚洲欧美| 欧美精品高潮呻吟av久久| 美女脱内裤让男人舔精品视频| 18在线观看网站| 国产精品亚洲av一区麻豆| 久久久精品94久久精品| 久久国产亚洲av麻豆专区| 亚洲欧美一区二区三区国产| 免费少妇av软件| 午夜免费男女啪啪视频观看| 免费女性裸体啪啪无遮挡网站| 久久国产精品大桥未久av| 日韩av在线免费看完整版不卡| 香蕉国产在线看| svipshipincom国产片| 男女高潮啪啪啪动态图| 国产成人a∨麻豆精品| 天天躁日日躁夜夜躁夜夜| 亚洲 欧美一区二区三区| 黄色毛片三级朝国网站| 女人爽到高潮嗷嗷叫在线视频| 一区二区三区乱码不卡18| 亚洲中文日韩欧美视频| 午夜福利影视在线免费观看| 99国产精品一区二区三区| 欧美国产精品va在线观看不卡| 精品少妇一区二区三区视频日本电影| 黑人巨大精品欧美一区二区蜜桃| 亚洲视频免费观看视频| 满18在线观看网站| 99国产精品一区二区三区| 永久免费av网站大全| 只有这里有精品99| 亚洲综合色网址| 精品高清国产在线一区| 国产精品久久久久久精品电影小说| 亚洲精品国产av成人精品| 亚洲欧美精品综合一区二区三区| 国产无遮挡羞羞视频在线观看| 97精品久久久久久久久久精品| 麻豆乱淫一区二区| 午夜视频精品福利| 国产主播在线观看一区二区 | 久久久欧美国产精品| 性高湖久久久久久久久免费观看| 免费观看人在逋| bbb黄色大片| 色综合欧美亚洲国产小说| 高清av免费在线| 国产视频首页在线观看| 啦啦啦视频在线资源免费观看| 天天躁日日躁夜夜躁夜夜| 97人妻天天添夜夜摸| 午夜两性在线视频| 国产又爽黄色视频| 美女高潮到喷水免费观看| 国产成人精品久久二区二区91| 欧美日韩视频精品一区| 亚洲色图 男人天堂 中文字幕| 中文字幕色久视频| 日日爽夜夜爽网站| 老司机靠b影院| 国产真人三级小视频在线观看| 欧美黄色片欧美黄色片| 亚洲av欧美aⅴ国产| 久9热在线精品视频| 多毛熟女@视频| 午夜免费鲁丝| 亚洲熟女毛片儿| 久久精品熟女亚洲av麻豆精品| 国产主播在线观看一区二区 | bbb黄色大片| 熟女av电影| 日韩熟女老妇一区二区性免费视频| 亚洲七黄色美女视频| 国产熟女午夜一区二区三区| 一区二区三区精品91| 在线av久久热| 久久九九热精品免费| 午夜福利乱码中文字幕| 女人被躁到高潮嗷嗷叫费观| 亚洲精品一区蜜桃| 久久精品国产亚洲av涩爱| 久久九九热精品免费| 午夜日韩欧美国产| 精品国产国语对白av| 久久久久久免费高清国产稀缺| 国产一区有黄有色的免费视频| 亚洲第一av免费看| 精品免费久久久久久久清纯 | 午夜久久久在线观看| 另类精品久久| 1024视频免费在线观看| www日本在线高清视频| 一个人免费看片子| 日韩,欧美,国产一区二区三区| 亚洲欧美精品自产自拍| 亚洲av成人精品一二三区| 黄片播放在线免费| 亚洲欧美一区二区三区国产| 免费看av在线观看网站| 亚洲久久久国产精品| 婷婷色综合大香蕉| 一级毛片女人18水好多 | 成年人黄色毛片网站| 亚洲 欧美一区二区三区| 日韩电影二区| 日韩伦理黄色片| 9热在线视频观看99| 中文字幕人妻丝袜一区二区| 午夜激情久久久久久久| 人人妻,人人澡人人爽秒播 | 亚洲国产精品成人久久小说| 久久女婷五月综合色啪小说| 久久精品久久精品一区二区三区| 考比视频在线观看| 十分钟在线观看高清视频www| 日韩 亚洲 欧美在线| 国产免费现黄频在线看| 成人影院久久| 男女无遮挡免费网站观看| 亚洲欧美成人综合另类久久久| 亚洲欧美中文字幕日韩二区| 色94色欧美一区二区| 亚洲av电影在线观看一区二区三区| 久久人人97超碰香蕉20202| 久久久亚洲精品成人影院| 91精品国产国语对白视频| 精品国产一区二区三区四区第35| 国产av一区二区精品久久| 国产亚洲av片在线观看秒播厂| 成人亚洲欧美一区二区av| 婷婷色麻豆天堂久久| 日本vs欧美在线观看视频| 国产激情久久老熟女| 大片免费播放器 马上看| 蜜桃在线观看..| 亚洲精品乱久久久久久| 成人国产一区最新在线观看 | 男人爽女人下面视频在线观看| 国产在线视频一区二区| 男女国产视频网站| 精品一区二区三卡| 色婷婷av一区二区三区视频| 欧美+亚洲+日韩+国产| 大香蕉久久成人网| 一级黄片播放器| 最近最新中文字幕大全免费视频 | 大话2 男鬼变身卡| 免费高清在线观看视频在线观看| 亚洲成人手机| 亚洲中文av在线| 9色porny在线观看| 国产在线观看jvid| 色婷婷av一区二区三区视频| 久久精品国产a三级三级三级| 18在线观看网站| 国产老妇伦熟女老妇高清| 看十八女毛片水多多多| av在线播放精品| 国产主播在线观看一区二区 | 久久精品aⅴ一区二区三区四区| 一级,二级,三级黄色视频| 久久这里只有精品19| 电影成人av| 爱豆传媒免费全集在线观看| 夜夜骑夜夜射夜夜干| 午夜福利视频在线观看免费| 免费看十八禁软件| 人人澡人人妻人| 精品亚洲乱码少妇综合久久| 老鸭窝网址在线观看| 日本av手机在线免费观看| 18禁观看日本| 中文字幕另类日韩欧美亚洲嫩草| 别揉我奶头~嗯~啊~动态视频 | 啦啦啦在线观看免费高清www| 五月天丁香电影| 国产伦理片在线播放av一区| 精品熟女少妇八av免费久了| 我要看黄色一级片免费的| 午夜免费观看性视频| 一本—道久久a久久精品蜜桃钙片| 悠悠久久av| 亚洲五月婷婷丁香| 麻豆乱淫一区二区| 亚洲精品久久久久久婷婷小说| 亚洲自偷自拍图片 自拍| 色94色欧美一区二区| 两个人看的免费小视频| 宅男免费午夜| 激情五月婷婷亚洲| avwww免费| av又黄又爽大尺度在线免费看| 自线自在国产av| 观看av在线不卡| 黄网站色视频无遮挡免费观看| 国产熟女欧美一区二区| 婷婷色综合www| 免费高清在线观看日韩| 亚洲欧美一区二区三区久久| 波野结衣二区三区在线| av国产久精品久网站免费入址| 精品人妻熟女毛片av久久网站| 日韩av免费高清视频| 丝袜喷水一区| 国产精品亚洲av一区麻豆| 精品人妻1区二区| 亚洲欧洲国产日韩| av天堂在线播放| 精品国产乱码久久久久久小说| 又紧又爽又黄一区二区| 超色免费av| 又紧又爽又黄一区二区| 嫁个100分男人电影在线观看 | 观看av在线不卡| 亚洲av综合色区一区| 国产精品偷伦视频观看了| 亚洲五月色婷婷综合| 久久天躁狠狠躁夜夜2o2o | 欧美精品一区二区免费开放| 婷婷成人精品国产| 免费在线观看黄色视频的| 每晚都被弄得嗷嗷叫到高潮| 后天国语完整版免费观看| 另类精品久久| 99精品久久久久人妻精品| 飞空精品影院首页| 亚洲欧洲国产日韩| 日本五十路高清| 性少妇av在线| 91成人精品电影| 极品人妻少妇av视频| 好男人电影高清在线观看| 国产国语露脸激情在线看| 黄色 视频免费看| 国产精品成人在线| 欧美日韩亚洲高清精品| 日本wwww免费看| 亚洲专区中文字幕在线| 亚洲av成人精品一二三区| 欧美+亚洲+日韩+国产| 人人妻人人澡人人看| 成人国产一区最新在线观看 | 国产真人三级小视频在线观看| 色婷婷av一区二区三区视频| 欧美精品高潮呻吟av久久| 久久久久视频综合| 精品一品国产午夜福利视频| 国产亚洲午夜精品一区二区久久| 午夜免费观看性视频| www.精华液| 两个人免费观看高清视频| www.熟女人妻精品国产| 人人妻人人爽人人添夜夜欢视频| 搡老乐熟女国产| 宅男免费午夜| 国产99久久九九免费精品| 欧美激情极品国产一区二区三区| 日日爽夜夜爽网站| 色网站视频免费| 大片免费播放器 马上看| 天天添夜夜摸| 亚洲av片天天在线观看| 人人妻人人爽人人添夜夜欢视频| 各种免费的搞黄视频| 国产成人欧美| 欧美在线一区亚洲| 啦啦啦视频在线资源免费观看| 午夜福利一区二区在线看| 午夜激情久久久久久久| 少妇被粗大的猛进出69影院| 男女边吃奶边做爰视频| 免费黄频网站在线观看国产| 在线观看免费午夜福利视频| 老司机在亚洲福利影院| 亚洲精品自拍成人| 丰满饥渴人妻一区二区三| 亚洲七黄色美女视频| 午夜日韩欧美国产| 久久精品国产亚洲av涩爱| 欧美另类一区| 新久久久久国产一级毛片| 两性夫妻黄色片| 国产亚洲一区二区精品| 欧美人与性动交α欧美精品济南到| 9热在线视频观看99| 人体艺术视频欧美日本| 9色porny在线观看| 亚洲成人国产一区在线观看 | 男女床上黄色一级片免费看| 又粗又硬又长又爽又黄的视频| 另类精品久久| 别揉我奶头~嗯~啊~动态视频 | 国产精品.久久久| 99久久99久久久精品蜜桃| 一二三四社区在线视频社区8| 桃花免费在线播放| 伊人久久大香线蕉亚洲五| 国产精品国产三级专区第一集| 亚洲国产精品成人久久小说| 国产熟女欧美一区二区| 亚洲精品av麻豆狂野| 国产又色又爽无遮挡免| 日韩伦理黄色片| 老司机影院成人| 90打野战视频偷拍视频| www日本在线高清视频| 日韩一本色道免费dvd| 99热全是精品| 女警被强在线播放| 天天影视国产精品| 制服人妻中文乱码| 亚洲av日韩精品久久久久久密 | 亚洲精品一二三| 黑人猛操日本美女一级片| 精品人妻在线不人妻| 99久久精品国产亚洲精品| 七月丁香在线播放| 亚洲精品av麻豆狂野| 青春草视频在线免费观看| 午夜av观看不卡| 日韩一区二区三区影片| 久久精品国产亚洲av高清一级| 久久久久久久久久久久大奶| 天天躁日日躁夜夜躁夜夜| 色94色欧美一区二区| 国产成人免费无遮挡视频| 在线观看国产h片| 欧美日韩成人在线一区二区| 99国产精品一区二区三区| 免费高清在线观看日韩| 美女福利国产在线| 国产亚洲欧美在线一区二区| xxxhd国产人妻xxx| 男女午夜视频在线观看| 一区二区三区精品91| 黄网站色视频无遮挡免费观看| 一级毛片黄色毛片免费观看视频| 9色porny在线观看| 国产欧美日韩一区二区三 | h视频一区二区三区| 桃花免费在线播放| 国产日韩欧美在线精品| 男女高潮啪啪啪动态图| www.av在线官网国产| 又黄又粗又硬又大视频| 亚洲精品久久久久久婷婷小说| 超碰97精品在线观看| 国产欧美日韩综合在线一区二区| 精品人妻1区二区| 国产激情久久老熟女| 男女床上黄色一级片免费看| 欧美乱码精品一区二区三区| 中国美女看黄片| 欧美日韩亚洲高清精品| 国产一区亚洲一区在线观看| 午夜久久久在线观看| 久热爱精品视频在线9| 国产伦人伦偷精品视频| 亚洲精品av麻豆狂野| 宅男免费午夜| 国产日韩一区二区三区精品不卡| 不卡av一区二区三区| 90打野战视频偷拍视频| 日日爽夜夜爽网站| 国产男女超爽视频在线观看| 亚洲成人手机| 久热这里只有精品99| 桃花免费在线播放| 亚洲三区欧美一区| 国产精品一国产av| 在线观看www视频免费| 波多野结衣一区麻豆| 亚洲成人免费电影在线观看 | www.精华液| 精品视频人人做人人爽| 免费久久久久久久精品成人欧美视频| 91字幕亚洲| 少妇的丰满在线观看| 日韩视频在线欧美| 日韩av免费高清视频| 在线观看免费视频网站a站| 91麻豆av在线| 涩涩av久久男人的天堂| 免费不卡黄色视频| 无遮挡黄片免费观看| 亚洲欧洲国产日韩| 自线自在国产av| 日韩一卡2卡3卡4卡2021年| 久久久久久人人人人人| 十八禁人妻一区二区| 欧美日韩黄片免| 国产欧美日韩综合在线一区二区| 伊人久久大香线蕉亚洲五| e午夜精品久久久久久久| 人人妻,人人澡人人爽秒播 | 亚洲情色 制服丝袜| 十八禁网站网址无遮挡| 亚洲国产精品一区三区| 亚洲久久久国产精品| 午夜日韩欧美国产| 国产成人精品久久二区二区91| 日本欧美国产在线视频| 中文字幕另类日韩欧美亚洲嫩草| 亚洲欧美清纯卡通| 色网站视频免费| 亚洲午夜精品一区,二区,三区| 国产福利在线免费观看视频| 手机成人av网站| 国产精品国产三级专区第一集| 亚洲精品在线美女| 亚洲五月婷婷丁香| 国产爽快片一区二区三区| 成年女人毛片免费观看观看9 | 日本一区二区免费在线视频| 尾随美女入室| 午夜福利在线免费观看网站| www.精华液| 久久精品久久久久久久性| 久久狼人影院| 人人妻人人澡人人爽人人夜夜| 99九九在线精品视频| 欧美日韩亚洲综合一区二区三区_| 青青草视频在线视频观看| 看十八女毛片水多多多| 亚洲精品一卡2卡三卡4卡5卡 | 最新的欧美精品一区二区| 中文字幕亚洲精品专区| 18禁裸乳无遮挡动漫免费视频| 午夜福利视频在线观看免费| 亚洲av电影在线观看一区二区三区| 午夜福利,免费看| 精品少妇内射三级| 国产成人精品无人区| 老汉色∧v一级毛片| 久久久久国产一级毛片高清牌| 热99久久久久精品小说推荐| 色播在线永久视频| 久久天躁狠狠躁夜夜2o2o | 精品国产一区二区久久| 日韩欧美一区视频在线观看| 中文字幕av电影在线播放| 国产精品久久久久久人妻精品电影 | 国产av精品麻豆| 秋霞在线观看毛片| 性少妇av在线| 免费看不卡的av| 欧美乱码精品一区二区三区| 亚洲精品自拍成人| 日本五十路高清| 成人影院久久| 你懂的网址亚洲精品在线观看| 久热爱精品视频在线9| 国产成人一区二区三区免费视频网站 | 大陆偷拍与自拍| 亚洲五月色婷婷综合| 精品久久久久久电影网| 亚洲精品一二三| 一本大道久久a久久精品| 亚洲熟女精品中文字幕| 日韩视频在线欧美| 啦啦啦视频在线资源免费观看| 满18在线观看网站| 纯流量卡能插随身wifi吗| 欧美中文综合在线视频| 午夜福利免费观看在线| 亚洲五月色婷婷综合| 18禁裸乳无遮挡动漫免费视频| 国产伦理片在线播放av一区| 我要看黄色一级片免费的| 国产熟女午夜一区二区三区| 久久精品熟女亚洲av麻豆精品| 黄色怎么调成土黄色| 交换朋友夫妻互换小说| 成人国产一区最新在线观看 | 十八禁网站网址无遮挡| 久久久久网色| 女警被强在线播放| 午夜免费男女啪啪视频观看| 女人爽到高潮嗷嗷叫在线视频| 免费高清在线观看视频在线观看| 97在线人人人人妻| 黄片播放在线免费| 在线看a的网站| 久久久久久久大尺度免费视频| 精品久久蜜臀av无|