Visualizing the Geometry of Hydrogen Dimers

The simplest molecular dimer, H2-H2, poses a challenge to both experiment and theory as a system with a multidimensional energy surface that supports only a single weakly bound quantum state. Here, we provide a direct experimental image of the structure of hydrogen dimers [(H2)2, H2-D2, and (D2)2] obtained via femtosecond laser-induced Coulomb explosion imaging. Our results indicate that hydrogen dimers are not restricted to a particular geometry but rather occur as a mixture of all possible configurations. The measured intermolecular distance distributions were used to deduce the isotropic intermolecular potential as well as the binding energies of the dimers.

最简单的分子二聚体（molecular dimer）H₂-H₂，作为一类具备多维能量表面且仅存在单个弱束缚量子态的系统，对实验与理论研究均构成挑战。本研究通过飞秒激光诱导库仑爆炸成像（femtosecond laser-induced Coulomb explosion imaging），获得了氢二聚体[(H₂)₂、H₂-D₂及(D₂)₂]结构的直接实验图像。结果表明，氢二聚体并非局限于某一特定几何构型，而是以所有可能构型的混合形式存在。我们利用测得的分子间距离分布，推导出了该类二聚体的各向同性分子间势能与结合能。