A molecular superfluid: non-classical rotations in doped para-hydrogen clusters

TL;DR

This study combines experiments and simulations to observe the onset of molecular superfluidity in doped para-hydrogen clusters, revealing size-dependent superfluid responses linked to solvation structures.

Contribution

It provides the first direct evidence of superfluid behavior in doped para-hydrogen clusters through combined experimental and theoretical approaches.

Findings

Reduction in effective inertia indicates superfluid response.

Superfluid response varies with cluster size and solvation structure.

Correlation between solvation rings and superfluidity observed.

Abstract

Clusters of para-hydrogen (pH2) have been predicted to exhibit superfluid behavior, but direct observation of this phenomenon has been elusive. Combining experiments and theoretical simulations, we have determined the size evolution of the superfluid response of pH2 clusters doped with carbon dioxide (CO2). Reduction of the effective inertia is observed when the dopant is surrounded by the pH2 solvent. This marks the onset of molecular superfluidity in pH2. The fractional occupation of solvation rings around CO2 correlates with enhanced superfluid response for certain cluster sizes.