Thermally created vacancies in the 1D chains of xenon adsorbed in the grooves of single-walled carbon nanotube bundles

The heat capacity of 1D chains of Xe adsorbed in the outer grooves of bundles of closed single-walled carbon nanotubes have been investigated in the temperature range from 2 to 55 K. The experimental results of heat capacity are close to the theoretical calculation below 8 K. Above 8 K the experimental curve exceeds the theoretical one and excess increases monotonously with temperature. It was assumed that the sharp increase of the difference between the experimental and theoretical curves of heat capacity above 30 K is associated with the occurrence of the thermally created vacancies in the chains due to spatial redistribution of the xenon atoms. The molar enthalpy of vacancy formation in the chain has been calculated.