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双原子分子多光子电离强场效应的含时波包动力学研究 总被引:1,自引:1,他引:0
强激光非线性条件下分子的多光子电离过程呈现出较为明显的强场效应.由于这种效应不能用传统的量子微扰论来处理,“缀饰态”模型方法提供了物理图象清晰的处理光与物质相互作用的方案.本文基于含时波包动力学的基本理论,将激光场看作经典场,利用“缀饰态”模型研究了强场下双原子分子(NO、RbI等)的多光子电离过程.研究表明,激光场的强度、泵浦-探测脉冲延迟时间等对多光子电离光电子能谱的形状有着重要的影响,而这种影响是由光诱导势引起的.另外,在研究具有两个连续态的RbI体系时,自电离现象的发生也与势能面的交叉密切相关,并受外场强度的影响.本文计算模拟外场中分子的光电子能谱时所得到的强场效应对理解和实现原子分子过程的激光操控具有重要的意义. 相似文献
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强激光非线性条件下分子的多光子电离过程呈现出较为明显的强场效应.由于这种效应不能用传统的量子微扰论来处理,"缀饰态"模型方法提供了物理图象清晰的处理光与物质相互作用的方案.本文基于含时波包动力学的基本理论,将激光场看作经典场,利用"缀饰态"模型研究了强场下双原子分子(NO、RbI等)的多光子电离过程.研究表明,激光场的强度、泵浦-探测脉冲延迟时间等对多光子电离光电子能谱的形状有着重要的影响,而这种影响是由光诱导势引起的.另外,在研究具有两个连续态的RbI体系时,自电离现象的发生也与势能面的交叉密切相关,并受外场强度的影响.本文计算模拟外场中分子的光电子能谱时所得到的强场效应对理解和实现原子分子过程的激光操控具有重要的意义. 相似文献
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用经典动力学和量子力学方法分别研究了H2+在超短强激光场中的电离、离解和残存行为,得到了相似的结果:即在超短强激光脉冲作用下,H2+的电离占优,但有限的量子计算低估了H2+的离解几率;而经典处理则没有显示H2+在超强场中的稳定化。另外,经典计算表明当核间距R伸展到一定范围时,H2+的电离率最大。这符合量子计算中发现的电荷谐振增强电离(CREI)现象。 相似文献
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利用三维经典系综模型,研究空间非均匀激光场驱动的氙原子非次序双电离,并对比了空间均匀激光场的情况.结果显示,波长较短时,空间非均匀激光场与空间均匀激光场的非次序双电离的产率较为相近.随着波长的增大,较高激光强度时空间非均匀激光场下非次序双电离受到越来越明显的抑制.相比于空间均匀激光场,空间非均匀激光场下非次序双电离两电子的末态发射角表现出更强烈的关联特性,特别在较大的激光波长下,两电子的末态发射角几乎全部集中在0°附近,这意味着两电子往往是平行发射到相同方向.此外,波长由近红外增大到中红外时,空间非均匀激光场下非次序双电离的有效再碰撞均由第1个电子的第1次返回主导,而空间均匀激光场下则呈现由第1次返回主导到第2次返回主导的转变.进一步,通过反演分析非次序双电离的经典轨迹,揭示了空间非均匀激光场下关联电子超快动力学过程的更多细节. 相似文献
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强激光非线性条件下分子的多光子电离过程呈现出较为明显的强场效应.由于这种效应不能用传统的量子微扰论来处理。“缀饰态”模型方法提供了物理图象清晰的处理光与物质相互作用的方案.本文基于含时波包动力学的基本理论,将激光场看作经典场,利用“缀饰态”模型研究了强场下双原子分子(NO、RbI等)的多光子电离过程.研究表明,激光场的强度、泵浦-探测脉冲延迟时间等对多光子电离光电子能谱的形状有着重要的影响。而这种影响是由光诱导势引起的.另外,在研究具有两个连续态的Rbl体系时,自电离现象的发生也与势能面的交叉密切相关,并受外场强度的影响.本文计算模拟外场中分子的光电子能谱时所得到的强场效应对理解和实现原子分子过程的激光搛控具有重要的意义. 相似文献
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在最近的实验和理论研究中,我们探讨了氩原子和氖原子在红外强激光场中低于再碰撞阈值的非序列双电离问题。在研究中,我们发现在非序列双电离过程中,氖原子的电子关联表现为在激光偏振面内肩并肩出射,而对于氩原子的电子关联行为表现为在激光偏振面内的背对背出射,我们采用三维半经典模型(考虑电子隧道电离)很好地解释了实验结果。在阈值附近,我们发现电子在激光场中的多次散射以及电子再碰撞激发后电子隧道电离是氩原子反关联行为的主要原因,而电子在激光场作用下的单次碰撞是电子关联行为的主要原因。通过测量双电离过程中产生电子的横向电子动量分布,观察到了库伦聚焦效应,我们认为这是非经典的关联行为。最后,我们给出了氩原子和氖原子在激光场中阈值的解析模型,并给出了原子的关联和反关联激光强度区域。 相似文献
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运用强场近似速度规范理论研究了激发态氢原子的电离情况,当ω1a.u.,γ1时(ω是激光场的频率,γ是Keldysh绝热参数),在线性极化激光场中推导了2pz态氢原子电离率的简单表达式,从公式中可以看出在低频极限的情况下,电离率和激光场频率ω成正比,这一公式对激发态氢原子电离机制的研究提供了重要的理论参考. 相似文献
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LIN Meirong JIN Shaojun LIU Yaoming ZHAO Qingchun ZHANG Baozheng 《Chinese Journal of Lasers》1995,4(4):329-333
ComputerizedSystemofMultiphotonIonizationSpectroscopy¥LINMeirong;JINShaojun;LIUYaoming;ZHAOQingchun;ZHANGBaozheng(Instituteof... 相似文献
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Applying time-independent non-perturbative formalism to the
photo-ionization of hydrogen atom immersed in a strong circularly
polarized standing electromagnetic wave, we calculate the shift of
energy levels and the distortion of wave functions for the
hydrogen atom, the ionization cross section induced by the
standing wave, and the angular distribution of photoelectrons and
obtain some interesting results. 相似文献
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Mohamed A. Mahmoud 《Central European Journal of Physics》2008,6(3):530-538
We have studied the formation of the molecular ion Rb2+ and the atomic ion Rb+. These are created in laser excited rubidium vapor at the first resonance, 5s–5p and 5p-nl transitions. A theoretical model
is applied to this interaction to explain the time evolution and the laser-power dependence of the population density of Rb+ and Rb2+. A set of rate equations which describe: the temporal variation of the population density of the excited states; the atomic
ion density; and the electron density, were solved numerically under the experimental conditions of Barbier and Cheret. In
their experiment the Rb concentration was 1×1013cm−3 and the laser power was taken to be 50–500 mW at vapor temperature = 450 K. The results showed that the main processes for
producing Rb2+ are associative ionization and Hornbeck-Molnar ionization. The calculations have also showed that, the atomic ions Rb+ are formed through the Penning Ionization (PI) and photoionization processes. Moreover, a reasonable agreement between the
experimental results and our calculations for the ion currents of the Rb+ and Rb2+ is obtained.
相似文献
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利用三维经典系综模型,研究了整个系综两电子(Ar原子为例)从激光场吸收的能量对激光参数(波长、激光强度和椭偏率)的依赖关系.结果显示,当激光强度固定,波长增加时,整个系综两电子从激光场吸收的能量整体呈上升趋势,但不同强度下趋势略有差异.在较低强度时整个系综两电子从激光场吸收的能量对波长的依赖关系呈现持续平稳增加的趋势,在较高强度时呈现先缓慢减小再快速增大的趋势.对强度的依赖关系在不同波长时呈现两个有趣的交叉点.对椭偏率的依赖关系在较低强度时呈现先逐渐减小再缓慢增大的趋势;在中等强度时呈现一个“阶梯型”即先缓慢增大再逐渐减小最后缓慢增大;在更高强度时呈现先逐渐增大再逐渐减小的趋势.为了解释整个系综两电子从激光场吸收的能量对激光参数的依赖关系,把整个系综的动力学过程分为双电离、单电离、受挫单电离和受挫双电离4种通道.然后分析各个通道的特征及其如何主导整个系综两电子从激光场吸收的能量的变化趋势.分析结果表明,整个系综两电子从激光场吸收的能量对波长、激光强度和椭偏率的依赖均是由于某种通道主导整个系综两电子从激光场吸收的能量的结果. 相似文献
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This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scanning the frequency of second laser field, it finds that the ionization probability shows several resonance peaks and is also much larger than the linear superposition of probabilities by applying two lasers separately. The enhancement of the ionization happens when the system is resonantly pumped to the excited states by absorbing two or more colour photons non-sequentially. 相似文献
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Multiphoton ionization of the hydrogen atom exposed to circularly or linearly polarized laser pulses
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This paper studies the multiphoton ionization of the
hydrogen atom exposed to the linearly or circularly polarized laser
pulses by solving the time-dependent Schr?dinger equation. It
finds that the ratio of the ionization probabilities by linearly and
circularly polarized laser pulses varies with the numbers of
absorbing photons. With the same laser intensity, the circularly
polarized laser pulse favors to ionize the atom with more ease than the
linearly polarized laser pulse if only two or three photons are
necessary to be absorbed. For the higher order multiphoton
ionization, the linearly polarized laser pulse has the advantage
over circularly polarized laser pulse to ionize the atom. 相似文献
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This paper studies the nonsequential double ionization(NSDI) process of diatomic molecules aligned parallel and perpendicular to an intense linearly polarized laser field by using a three-dimensional semiclassical model.With this model,it achieves insight into the ion momentum distribution under the combined influence of a two-centre Coulomb potential and an intense laser field,and this result shows the significant influence of molecular alignment on the ratio between double and single ionization rate.Careful investigations show that the NSDI process for different alignment molecules has a close relation to the laser intensity and the different bounding electron distribution has a significant influence on the final ion momentum distribution. 相似文献