Quantum states and specific heat of low-density He gas adsorbed within the carbon nanotube interstitial channels: Band structure effects and potential dependence

TL;DR

This study investigates how the quantum band structure of helium gas confined in carbon nanotube channels affects its specific heat, revealing nonmonotonic temperature dependence linked to band gaps.

Contribution

It provides the first detailed calculation of helium's band structure in nanotube channels and its impact on thermodynamic properties.

Findings

Specific heat exhibits nonmonotonic temperature dependence.

Band gaps in the density of states influence thermodynamic behavior.

Quantum effects are significant in low-density helium adsorption.

Abstract

We calculate the energy-band structure of a He atom trapped within the interstitial channel between close-packed nanotubes within a bundle and its influence on the specific heat of the adsorbed gas. A robust prediction of our calculations is that the contribution of the low-density adsorbed gas to the specific heat of the nanotube material shows pronounced nonmonotonic variations with temperature. These variations are shown to be closely related to the band gaps in the adsorbate density of states.