We theoretically investigate the formation of the high-order fractional alignment echo in OCS molecule and systematically study the dependence of echo intensity on the intensities and time delay of the two excitation pulses. Our simulations reveal an intricate dependence of the intensity of high-order fractional alignment echo on the laser conditions. Based on the analysis with rotational density matrix, this intricate dependence is further demonstrated to arise from the interference of multiple quantum pathways that involve multilevel rotational transitions. Our result provides a comprehensive multilevel picture of the quantum dynamics of high-order fractional alignment echo in molecular ensembles, which will facilitate the development of “rotational echo spectroscopy.”

中文翻译：

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高阶分数分子排列回波形成中的多级量子干扰

我们从理论上研究了OCS分子中高阶分数对准回波的形成，并系统地研究了回波强度对两个激发脉冲的强度和时间延迟的依赖性。我们的仿真揭示了高阶分数对准回波的强度对激光条件的复杂依赖性。基于对旋转密度矩阵的分析，这种复杂的依赖性被进一步证明是由涉及多级旋转跃迁的多个量子路径的干扰引起的。我们的结果提供了分子集合中高阶分数对准回波的量子动力学的全面的多层次图片，这将有助于“旋转回波光谱学”的发展。