光场的线宽对无粒子数反转光放大增益的影响

针对拉曼驱动场下的四能级理论模型，讨论了实现无吸收、高折射率的条件，并分析了探测场及相干激发场的线宽对介质的折射率及增益的影响。计算结果表明，改变相干激发场 场强，或改变相干场的频率与原子能级间的失谐均可获得介质的无吸收，高折射率。激发扬线宽破坏了原子的相干性，使使介质的增闪下降并改变了折射率的大小，探测场的线宽使介质的探测增益谱及折射率谱的分辨率下降。     

光场的空间横向效应对无粒子数反转光放大增益的影响

针对喇曼场驱动下的四能级理论模型，讨论了光场的空间横向效应对无粒子数反转光放大增益的影响．计算结果表明：光场的空间横向效应使探测场的探测谱形状发生了变化；为了在样品池的出口处获得较高增益，汇聚透镜的最佳聚焦位置不应在样品池的中心，而应在样品池的出口附近． 关键词：     

高QKerr介质腔中光场相位自调制效应对原子布居的影响

研究了高Q kerr介质腔中的二能级原子与双模光场相互作用系统中,光场的相位自调制效应对原子布居的影响. 研究发现随着相位自调制强度的增加, 原子与光场的耦合减弱,并证明光场相位自调制强度与光场的各模有关. 同时分析讨论了光子数对原子布居的影响.     

飞秒激光脉宽对非绝热耦合分子波包运动的影响研究

利用含时波包法研究了强飞秒泵浦-探测激光场中激光脉宽对非绝热耦合NaI分子波包运动的影响.发现波包的振荡周期随脉宽增长而增大,而振荡幅度随脉宽增长而减小.非绝热效应引起的波包在交叉区域的分裂情况影响各态布居.脉宽增长,NaI分子的激发概率增大,而解离概率减小.研究表明调节激光场脉宽可实现对波包运动的控制从而控制态布居的选择性分布.研究结果可以为实验上实现分子的光控制以及量子调控过程提供一定的参考.     

调制振幅对粒子布居几率振荡的影响

为探讨调频场导致的量子效应的物理本质,运用密度矩阵方程和布洛赫矢量模型,对调频场作用下二能级原子系统中的粒子布居几率振荡现象进行了理论分析,讨论了光场调制振幅对振荡过程的影响。理论计算结果表明,光场调制振幅对粒子布居转移和几率振荡有较大的调制作用。当其他参量不变时,随着调制振幅的增大,粒子布居几率振荡减弱,布居转移效率增高,吸收增强。布洛赫矢量分析表明,该振荡过程是系统粒子数转移、吸收和极化三者之间的动态变化过程。     

量子Zeno效应对原子布居翻转的影响

在量子信息的研究中,量子Zeno效应(QZE)的研究对量子信息的处理有重要作用.针对原子—场相互作用系统,在Jaynes Cummings(JC)模型下,研究在不同测量时间间隔中,布居翻转与初态存活概率的变化趋势.同时得出在时间间隔足够小时,产生QZE,进而得出QZE对布居翻转的影响.     

量子Zeno效应对原子布居翻转的影响

在量子信息的研究中,量子Zeno效应（QZE）的研究对量子信息的处理有重要作用.针对原子—场相互作用系统,在Jaynes Cummings ( JC) 模型下,研究在不同测量时间间隔中, 布居翻转与初态存活概率的变化趋势.同时得出在时间间隔足够小时,产生QZE,进而得出QZE对布居翻转的影响.     

Coriolis耦合对Cl+H2→H+HCl非绝热反应的影响

使用含时波包方法 ,在Capecchi和Werner拟合的非绝热耦合势能面上 ,研究了Cl处在自旋轨道基态以及自旋轨道激发态时与H2 反应的活性 ,并且讨论了Coriolis耦合的影响 .计算了某些角动量时的反应几率 .计算结果显示 ,当Cl原子处在自旋轨道激发态与处在基态的H2 的反应活性很小 ,Coriolis耦合在这个反应中起了很小的作用 .     

原子-多原子分子反应的含时波包理论研究

基于Modified Jordan和Gilbert的势能面,运用SVRT(semirigid vibrating rotor target)模型和TDWP(Time-Dependent Wave Packet)方法,对D+CH4,O(3P)+CH4反应体系进行了含时波包动力学研究,计算得到了不同初始振动态的总反应几率,总散射截面和热速率常数.通过对j=0时,v=0,1的反应几率的计算,看出H-CH3的振动激发,极大地提高了反应几率,而反应阈能明显降低,说明反应分子的振动能对分子的碰撞反应有重要贡献.     

场极化方向对强激光加速电子效应的影响

模拟研究了光场极化方向对自由电子与线偏振强激光束间发生净能量交换(非弹性散射及加速效应)的影响.研究结果表明,当光场强度0.1a01时(a0＝eE0/mecω),电子在激光束上的散射呈现弱的非弹性效应,且与场的线偏振极化方向无关,表现为空间各向同性,与有质动力势模型的结果定性一致.而当a010时,电子与光场间的净能量交换不仅变得明显,而且依赖于电子入射方向与场极化面之间的夹角.当电子沿电场极化面入射时,净能量交换效应最显著,随着这一夹角的增大,这一效应逐渐减弱乃至消失.此时电子在强光束上的散射表现出明显的空间各向异性,有质动力势模型已完全不再适用.     

The influence of femtosecond laser parameters on the wavepacket and population of the diabatic excited states of NaLi

Using the three-state model and time-dependent wavepacket method, the influence of the parameters of the intense femtosecond laser field on the wavepacket dynamic process of the double-minimum potential state 5¹Σ⁺ and the population of the ground and diabatic electronic states of NaLi are investigated. The calculations show that different femtosecond laser parameters result in different influences on the evolution of the wavepacket and the population of NaLi. With increasing laser intensity and wavelength the diabatic coupling strength between A and B states first strengthens and then weakens. The population interchanges between A and B states when the laser pulse disappears. The above results provide the suggestions and useful information for one to achieve quantum manipulation of the molecule in an experiment.     

Influence of laser fields on the vibrational population of molecules and its wave-packet dynamical investigation

The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules.For a two-state system in laser fields,the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schro¨dinger equation with the splitoperator method.The calculation shows that the field parameters,such as intensity,wavelength,duration,and delay time etc.can have different influences on the vibrational population.By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state,which will benefit the light manipulation of atomic and molecular processes.     

Theoretical study of the influence of intense femtosecond laser field on the evolution of the wave packet and the population of NaRb molecule

Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 6{ }^1\Sigma ^ + state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes.     

The effect of field modulation on the vibrational population of the photoassociated NaK and its dynamics

This paper presents calculation results for the photoassociation of a NaK molecule with a two-color modulated laser and gives a detailed analysis about them.For the two-step photoassociation process in intense fields,the effect of two-color modulated laser parameters,such as relative phase,envelope period,and laser intensity,on the population of the molecular electronic state can be obtained by solving the time-dependent Schrodinger equation through the quantum wave packet method.The numerical simulation shows not only that the influence of laser parameters on the vibrational distribution presents some regularity,but also that a higher population in the ground electronic state can be realized through adjusting these laser parameters.     

Theoretical study on lower electronic states of the FeSi molecule

The low lying electronic states of the FeSi molecule have been investigated by performing complete active space self-consistent field (CASSCF) and multireference single and double excitation configuration interaction (MRSDCI) calculations. Although the classification of the ground state was not established, the results of the MRSDCI calculations suggest that the ground state of FeSi is ³Δ, and the lowest excited state is ⁵Π whose transition energy is 0.36 eV including the Davidson-type Q correction. The R _e given by MRSDCI with Q correction is 2.23 Å for ³Δ and 2.19 Å for ⁵Π. The spectroscopic constants and dipole moments of the low lying ⁵Δ and ³Π states as well as the ³Δ and ⁵Π states are also evaluated. The bonding nature of FeSi in the ³Δ state is discussed in comparison with the FeC molecule.     

激光光强扰动对相干场成像降质影响理论研究

激光相干场成像系统发射多束激光,经大气传输对远程目标成像,大气湍流引起的激光束光强扰动是影响成像质量的一个关键因素.本文从湍流引起的激光束光强扰动对回波解调信号的影响关系入手,建立了激光回波光强扰动因子对相位闭合系数和成像频谱分量的降质传函理论模型;基于三光束激光相干场成像系统仿真验证了理论模型的有效性.研究表明激光相干场成像频谱分量和成像像质主要受三光束相位闭合求解算法中第二光束光强扰动影响.该研究揭示了激光回波光强扰动对成像像质的影响机理,对于分析大气湍流等引起的光强扰动降质效应和合理分配多光束光强稳定性以提高成像质量具有理论指导意义.     

GeO分子激发态的电子结构和跃迁性质的组态相互作用方法研究

应用多参考组态相互作用方法计算了GeO分子的第一解离极限(Ge(³P_g)+O(³P_g))对应的18个Λ-S电子态的电子结构. 计算中纳入了Ge原子的3d轨道电子的内壳层-价壳层电子关联效应、标量相对论效应和Davidson修正. 基于计算的电子态的电子结构, 通过求解径向Schrödinger方程获得了束缚电子态的光谱常数R_e, T_e, ω_e, ω_eχ_e, B_e, 理论计算给出的这些电子态的光谱常数与之前的实验结果符合得很好. 计算了电子态的电偶极矩随核间距的变化, 分析了电子态的组态成分的变化对电偶极矩的影响. 计算的势能曲线表明, 激发态A¹Π, 1¹Σ^-, D¹Δ, a³Π, a’³Σ⁺, d³Δ 和 e³Σ^-的绝热激发能密集地分布于26000-37000 cm^-1范围内, 这些密集分布的电子态之间的相互作用对振动波函数有明显扰动作用. 借助于激发态之间的自旋-轨道耦合矩阵元, 阐明了邻近的激发态对A¹Π和a³Π的扰动作用. 基于计算的A¹Π-X¹Σ⁺和A’¹Σ⁺-X¹Σ⁺跃迁的电偶极跃迁矩和Franck-Condon 因子, 给出了A¹Π 和A’¹Σ⁺态的最低的六个振动能级的辐射寿命.     

强激光场中H~-离子二维光电子动量谱的理论研究

选用两个模型势,利用强场近似方法研究了H-离子在线性极化强激光场中二维光电子动量谱中次外层后重散射环.研究结果表明:两个模型势中的极化势对二维光电子动量谱的影响很小;随着激光强度的增加,二维光电子动量谱中出现后重散射环的数目变多,沿着次外层后重散射环的光电子的角分布波动性变小,能够通过多项式拟合的方法从二维光电子动量谱中次外层后重散射环获得精确的电子与H原子的弹性散射截面,特别适用于激光强度较小的情况.     

Theoretical study of the electronic states and transition dipole moments of the LiK molecule

The adiabatic potential energy, the spectroscopic constants and the transition dipole moments of the lowest electronic states of the LiK⁺ molecule, dissociating into Li(2s, 2p, 3s, 3p, 3d, 4s, and 4p) + K⁺ and Li⁺ + K(4s, 4p, 5s, 3d, 5p, 4d, and 6s), have been investigated. We have used an ab initio approach involving a non-empirical pseudopotential for the Li (1s²) and K (1s²2s²2p⁶3s²3p⁶) cores and core valence correlation correction. A very good agreement has been obtained for the ground state for the spectroscopic constants with the available theoretical works. The transition dipole moment from X²Σ, 2²Σ, 3²Σ, and 4²Σ states to higher excited states have been determined. Numerous avoided crossing between electronic states of ²Σ and ²Π symmetries, have been localised and analysed. Their existences are related to the charge transfer process between the two ionic systems Li⁺K and LiK⁺.     

Influence of laser intensity on the double-resonance multiphoton ionization process of NO molecule

The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.