  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.
