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Harmonic Enhancement Mechanism of a Superposition State Atom Irradiated by Short Pulses 总被引:1,自引:0,他引:1
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We investigate the high-order harmonic generation (HHG) of a model atom whose initial state is prepared in a superposition of its ground state and an excited state irradiated by different duration laser pulses. Compared to the HHG generated from an atom whose initial state is in its ground state, its conversion efficiency obtains some enhancement. The enhancement originates from the higher ionization rate (rather than the ionization yield) of the atom with superposition initial state. 相似文献
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Field-Free Molecular Orientation Generated from Cyclic Rotational States by Using Two Trains of Half-Cycle Pulses
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We show that two trains of half-cycle pulses (HCPs) with different amplitudes irradiating alternately on polar molecules can achieve a remarkable enhancement of field-free orientation compared with the case of an equal amplitude HCPs train for the same pulse separation. optimal adjustment of the population distribution on This kind of orientation enhancements is mainly due to an every field-free angular momentum eigenstate, in which the populations on the undesired states of high angular momenta are effectively suppressed, and the populations on the desired states of low angular momenta are correspondingly promoted. 相似文献
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We demonstrate theoretically that the high-order harmonic of an atom can be generated by a circularly polarized laser pulse.The harmonic spectrum shows a clear cutoff with an energy Ip + 2Up.In particular,the high-order harmonic generation comes from the multiple recombination of the ionized electron with non-zero initial velocity.These results are verified by the classical model theory and the time-frequency analysis of a harmonic spectrum. 相似文献
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不同维度模型原子隧穿电离研究 总被引:1,自引:0,他引:1
本文数值求解一维和二维模型原子在强激光场作用下含时Schr??dinger方程,研究了在隧穿电离区相同基态能量和相同峰值场强条件下二者的电离速率,发现一维模型计算得到的电离速率比二维的结果大很多.产生该电离速率差别的原因是不同维度下束缚电子所需隧穿的含时势垒的不同. 相似文献
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本文研究了单电子分子离子与强激光场相互作用下的高次谐波发射谱。从光谱中观察到除了存在入射激光频率奇数倍的谐波谱线外,还存在其他频率的超拉曼谱线。在理论上阐明了超拉曼谱线不同于高次谐波谱线的物理产生机制。研究发现当体系初态为基态和较高激发态的叠加态时能够较清晰的观察到超拉曼谱线,从而说明激发态电子的布居对超拉曼谱线的产生起着关键作用。因此在实验上,制备一个叠加态使得电子从激发态电离,是观察到超拉曼谱线的重要条件。 相似文献
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使用二阶对称分拆光谱方法和一维短程势原子模型对强光辐照下原子的高次谐波谱进行了重新计算 ,第一次实现了强场方程解的边界完备性 ,从而获得了更为清晰的谐波谱和展宽的谐波平台.An exact solution of the intense-field Schr dinger equation is obtained by using the 1D short-range potential model and symmetrically splitting time-evolution operator spectral method. This solution is the first one defined in the full space without any pre-assumed boundary condition. A novel high-order harmonic spectrum is computed based on our wavefunctions. It is found that this spectrum displays clearer harmonic peaks and a wider plateau than that predicted by I p+3.2U p. 相似文献
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通过数值求解一维含时薛定谔方程,本文研究了组合脉冲与氢原子模型相互作用的高次谐波谱,组合脉冲由基频钛宝石激光和它的二次谐波构成. 研究发现,当两束脉冲之间的相对相位取值不同时,谐波谱的截止位置呈现较大差异. 对此,采用半经典的“三步”模型给出了合理的分析. 本文的数值结果表明,尽管双色谐波谱的结构复杂,截止频率不能用一个简单的公式表示,但通过“三步”模型计算同样能准确预言出截止频率. 相似文献
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