Civita Donato, Timm Matthew, Schwarz Jutta, Hecht Stefan, Grill Leonhard
Department of Physical Chemistry, University of Graz, Heinrichstraße 28, Graz 8010, Austria.
Department of Chemistry & Center for the Science of Materials Berlin, Humboldt University Berlin, Brook-Taylor-Str. 2, Berlin 12489, Germany.
ACS Nano. 2025 Mar 18;19(10):10255-10262. doi: 10.1021/acsnano.4c17652. Epub 2025 Mar 5.
The breaking of an interatomic bond is at the heart of chemistry yet remains a challenge to be investigated. Molecules on metal surfaces exhibit defined positions and orientations and can be characterized by scanning tunneling microscopy that moreover is able to trigger bond breaking. Until now, the bond dissociation dynamics has been studied in small molecules but not in large ones with various degrees of freedom. Here, we dissociate bromine atoms from single dibromo-terfluorene molecules on Ag(111), identifying not only the displacement but also the rotation of each fragment. It turns out that the molecular excitation that causes dissociation is not locally confined. Instead, it can propagate through the molecule, and the dynamics of the resulting fragments is uncorrelated. The fragment binds to the nearest silver atom after dissociation and dissipates its energy in rotational motion. Our findings could be useful for the precise engineering of chemical reactions with prearranged precursor molecules.
原子间键的断裂是化学的核心问题，但仍是有待研究的挑战。金属表面的分子具有确定的位置和取向，可通过扫描隧道显微镜进行表征，而且该显微镜还能够引发键的断裂。到目前为止，键解离动力学已在小分子中得到研究，但尚未在具有各种自由度的大分子中进行研究。在此，我们使溴原子从Ag(111)上的单个二溴三氟芴分子中解离，不仅确定了每个碎片的位移，还确定了其旋转。结果表明，导致解离的分子激发并非局限于局部。相反，它可以在分子中传播，并且产生的碎片的动力学是不相关的。碎片在解离后与最近的银原子结合，并通过旋转运动耗散其能量。我们的发现可能有助于利用预先安排的前驱体分子精确设计化学反应。
