The heat capacity of nitrogen chains in grooves of single-walled carbon nanotube bundles

TL;DR

This study experimentally investigates the heat capacity of nitrogen molecules adsorbed in the grooves of single-walled carbon nanotube bundles from 2K to 40K, revealing contributions from phonons and rotational degrees of freedom.

Contribution

First experimental measurement of nitrogen chain heat capacity in SWNT grooves, highlighting rotational effects and comparing with theoretical phonon models.

Findings

C(T) is linear below 3K

C(T) behavior aligns with 1D phonon models between 2-8K

Rotational degrees of freedom influence heat capacity above 8K

Abstract

The heat capacity of bundles of closed-cap single-walled carbon nanotubes (SWNT) with one-dimensional chains of nitrogen molecules adsorbed in the grooves has been first experimentally studied at temperatures from 2K to 40K using an adiabatic calorimeter. The contribution of nitrogen C(T) to the total heat capacity has been separated. In the region 2-8K the behaviour of the curve C(T) is qualitatively similar to the theoretical prediction of the phonon heat capacity of 1D chains of krypton (Kr) atoms localized in the grooves of SWNT bundles. Below 3K the dependence C(T) is linear. Above 8K the dependence C(T) becomes steeper in comparison with the case of Kr atoms. This behaviour of the heat capacity C(T) is due to the contribution of the rotational degrees of freedom of the nitrogen molecules.