Internal dynamics and "superfluidity" in small helium and hydrogen clusters

用毫米波光谱学研究掺入探测分子的氦原子或氢分子的几到几十个小团簇，以便根据它们的大小来表征这些团簇的性质。这项研究旨在解决与超流的微观性质有关的基本问题，即超流的开始需要多少个氦原子，以及氢是否可以成为超流体？超高灵敏度的内腔光谱仪OROTRON将测量超音速喷流中冷星团的转动光谱。由于这些体系的性质与纯氦或氢团簇的性质非常相似，与其他体系相比，迄今没有记录到纯转动光谱，因此活性将仅限于掺入一氧化碳、HEN-CO和(H2)N-CO的团簇。此外，在小到中等团簇尺寸范围内，建立络合物的旋转动力学与其超流体响应之间的关系是本提议的目标。

Small clusters counting a few to several tens helium atoms or hydrogen molecules doped with a probe molecule will be investigated by millimeter-wave spectroscopy in order to characterize the properties of these clusters in dependence on their size. This study is intended to address fundamental questions related to the microscopic nature of superfluidity, namely, what number of helium atoms is required for the onset of superfluidity and whether hydrogen can be made superfluid? Rotational spectra of cold clusters in a supersonic jet will be measured with the ultrahigh sensitivity intracavity spectrometer, OROTRON. Activities will be constrained to clusters doped with carbon monoxide, HeN-CO and (H2)N-CO, since the properties of these systems are very similar to those of pure helium or hydrogen clusters and in contrast to other systems to date no pure rotational spectra have been recorded. Furthermore, establishment of a relation of rotational dynamics of the complex to its superfluid response in the small to intermediate cluster size regime are the goals of present proposal.