We theoretically study the Autler–Townes (AT) splitting of a molecule in a circularly polarized laser pulse by solving the time-dependent Schrödinger equation. We find that the AT doublet in the photoelectron momentum distribution reveals different angular shifts with respect to the molecular axis direction. Using an improved strong-field approximation method, we reproduce the difference of the angular shifts for the AT doublet, which originates from the interference of the electron wave packets released from the ground and excited states of the molecule. By tracing the time evolution of the electron density distribution along the molecular axis, we find that electron delocalization on the two nuclei of the molecule plays a significant role in the formation of photoelectron angular distribution for the AT doublet, which corresponds to a phase jump of π for the phase difference between the ground and excited states.

中文翻译：

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圆偏振激光脉冲对分子的多光子电离导致 Autler-Townes 双峰的角位移

我们通过求解随时间变化的薛定谔方程从理论上研究圆偏振激光脉冲中分子的 Autler-Townes (AT) 分裂。我们发现光电子动量分布中的 AT 双峰显示出相对于分子轴方向的不同角度偏移。使用改进的强场近似方法，我们重现了 AT 双峰角位移的差异，这源于从分子的基态和激发态释放的电子波包的干扰。通过追踪沿分子轴的电子密度分布的时间演化，我们发现分子两个核上的电子离域在 AT 双峰的光电子角分布的形成中起着重要作用，π对于基态和激发态之间的相位差。