Much of our knowledge about dynamics and functionality of molecular systems has been achieved with femtosecond time-resolved spectroscopy. Despite extensive technical developments over the past decades, some classes of systems have eluded dynamical studies so far. Here, we demonstrate that superfluid helium nanodroplets, acting as a thermal bath of 0.4 K temperature to stabilize weakly bound or reactive systems, are well suited for time-resolved studies of single molecules solvated in the droplet interior. By observing vibrational wave packet motion of indium dimers (${\mathrm{In}}_2$) for tens of picoseconds, we demonstrate that the perturbation imposed by this quantum liquid can be lower by a factor of 10–100 compared to any other solvent, which uniquely allows us to study processes depending on long nuclear coherence in a dissipative environment. Furthermore, tailor-made microsolvation environments inside droplets will enable us to investigate the solvent influence on intramolecular dynamics in a wide tuning range from molecular isolation to strong molecule-solvent coupling.

中文翻译：

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氦纳米液滴内部的长寿命核相干

飞秒时间分辨光谱学已经获得了我们关于分子系统动力学和功能的许多知识。尽管在过去的几十年中技术领域取得了长足的发展，但到目前为止，仍然没有进行动力学研究。在这里，我们证明了超流体氦纳米液滴（充当0.4 K温度的热浴，以稳定弱结合或反应系统）非常适合于液滴内部溶剂化的单分子时间分辨研究。通过观察铟二聚体的振动波包运动（${在}_2$）在数十皮秒的时间内，我们证明了与任何其他溶剂相比，这种量子液体所施加的扰动可以降低10-100倍，这使得我们能够根据耗散环境中的长核相干性来研究过程。此外，液滴内部特制的微溶剂化环境将使我们能够在从分子分离到牢固的分子-溶剂偶联的广泛调节范围内研究溶剂对分子内动力学的影响。