State Key Laboratory of Precision Spectroscopy, East China Normal University, 200062, Shanghai, China.
Key Laboratory for laser Plasmas (Ministry of Education) and School of Physics and Astronomy, Collaborative innovation center for IFSA (CICIFSA), Shanghai Jiao Tong University, 200240, Shanghai, China.
Nat Commun. 2019 Feb 14;10(1):757. doi: 10.1038/s41467-019-08700-5.
Atoms and molecules exposed to strong laser fields can be excited to the Rydberg states with very high principal quantum numbers and large orbitals. It allows acceleration of neutral particles, generate near-threshold harmonics, and reveal multiphoton Rabi oscillations and rich photoelectron spectra. However, the physical mechanism of Rydberg state excitation in strong laser fields is yet a puzzle. Here, we identify the electron-nuclear correlated multiphoton excitation as the general mechanism by coincidently measuring all charged and neutral fragments ejected from a H molecule. Ruled by the ac-Stark effect, the internuclear separation for resonant multiphoton excitation varies with the laser intensity. It alters the photon energy partition between the ejected electrons and nuclei and thus leads to distinct kinetic energy spectra of the nuclear fragments. The electron-nuclear correlation offers an alternative visual angle to capture rich ultrafast processes of complex molecules.
处于强激光场中的原子和分子可以被激发到具有非常高主量子数和大轨道的里德伯态。这使得中性粒子的加速、产生近阈值谐波以及揭示多光子拉比振荡和丰富的光电子谱成为可能。然而，强激光场中里德伯态激发的物理机制仍然是一个谜。在这里，我们通过同时测量从 H 分子中逐出的所有带电和中性碎片，确定电子-核相关的多光子激发是普遍机制。受 ac-Stark 效应的控制，共振多光子激发的核间分离随激光强度而变化。它改变了被逐出的电子和原子核之间的光子能量分配，从而导致核碎片的动能谱明显不同。电子-核相关性提供了一个替代的视角，可以捕捉复杂分子中丰富的超快过程。
