Feinberg Alexandra J, Verma Deepak, O'Connell-Lopez Sean M O, Erukala Swetha, Tanyag Rico Mayro P, Pang Weiwu, Saladrigas Catherine A, Toulson Benjamin W, Borgwardt Mario, Shivaram Niranjan, Lin Ming-Fu, Al Haddad Andre, Jäger Wolfgang, Bostedt Christoph, Walter Peter, Gessner Oliver, Vilesov Andrey F
Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
RA3, Intel Corporation, Ronler Acres, 2501 NE Century Blvd, Hillsboro, OR 97124, USA.
Sci Adv. 2021 Dec 10;7(50):eabk2247. doi: 10.1126/sciadv.abk2247.
Quantum fluid droplets made of helium-3 (He) or helium-4 (He) isotopes have long been considered as ideal cryogenic nanolabs, enabling unique ultracold chemistry and spectroscopy applications. The droplets were believed to provide a homogeneous environment in which dopant atoms and molecules could move and react almost as in free space but at temperatures close to absolute zero. Here, we report ultrafast x-ray diffraction experiments on xenon-doped He and He nanodroplets, demonstrating that the unavoidable rotational excitation of isolated droplets leads to highly anisotropic and inhomogeneous interactions between the host matrix and enclosed dopants. Superfluid He droplets are laced with quantum vortices that trap the embedded particles, leading to the formation of filament-shaped clusters. In comparison, dopants in He droplets gather in diffuse, ring-shaped structures along the equator. The shapes of droplets carrying filaments or rings are direct evidence that rotational excitation is the root cause for the inhomogeneous dopant distributions.
由氦 - 3（He）或氦 - 4（He）同位素构成的量子流体微滴长期以来一直被视为理想的低温纳米实验室，可实现独特的超冷化学和光谱学应用。人们认为这些微滴能提供一个均匀的环境，在其中掺杂原子和分子几乎可以像在自由空间中一样移动和反应，但温度接近绝对零度。在此，我们报告了对掺杂氙的He和He纳米微滴进行的超快X射线衍射实验，证明孤立微滴不可避免的旋转激发会导致主体基质与封闭掺杂剂之间产生高度各向异性且不均匀的相互作用。超流He微滴布满了捕获嵌入粒子的量子涡旋，导致形成丝状簇。相比之下，He微滴中的掺杂剂沿赤道聚集在弥散的环形结构中。携带丝状或环形的微滴形状直接证明了旋转激发是掺杂剂分布不均匀的根本原因。
