Thermodynamics of low-dimensional adsorption in grooves, on the outer surface, and in interstitials of a closed-ended carbon nanotube bundle

Abstract

The thermodynamics of an atomic deposit adsorbed in grooves, on the outer surface, and in interstitials of a closed-end carbon nanobundle is investigated theoretically. The model takes into account the interparticle interaction in the primary and secondary chains of the groove subsystem as well as the interaction between atoms from different chains. The thermodynamic potential for the groove subsystem is calculated exactly within the transfer-matrix method. The interstitials, two-dimensional deposit on the outer bundle surface and three-dimensional atmosphere of the cell, are included into consideration through the appropriate balance condition. The average adsorbate densities, adsorption isotherms, isosteric heat, and heat capacity are calculated. The behavior of these quantities is analyzed in detail at different relations between the parameters of the system. The theoretical results are in good quantitative agreement with the experimental data on thermodynamics of $^{4}\mathrm{He}$ adsorbate.