Driving force of molecular/ionic superfluid formation

Abstract

Ordered- and high-flux flow of molecules and ions in biological channels is considered as a quantum-confined superfluid, which is highly important in chemical reactions and bioinformation transmission. However, the driving forces for these ordered arrangements of molecules and ions in confined spaces have not been discussed. Herein, we demonstrate that the driving force of molecular/ionic superfluid formation is the attraction-repulsion balance of particles under the effect of interfacial confinement, as well as the space-confinement effect enough to reduce the degrees of freedom of the particles and then greatly limit the disorder of their movement. The competition of attractive potential energy (E) with the disorder caused by thermal noise (kBT) results in the phase transition temperature. When |E| > kBT, an ordered structure of the particles can be formed. A superfluid of 4He atoms is formed below 2.17 K. Molecules or ions can achieve a superfluid at a higher phase transition temperature (near body temperature) under a certain confined distance, for example, about twice van der Waals equilibrium distance (2d0) for molecules and twice Debye length (2λD) for ions and ion-molecules. Owing to the unique characteristic of ultralow resistance for particle transport, molecular/ionic super-fluids will have a significant impact in areas such as energy transfer, storage, and conversion.