Phonons and specific heat of neon and methane on the surface of a nanotube bundle

Abstract

Adsorbed Ne and CH 4 on the external surface of a nanotube bundle form quasi-one-dimensional phases at low temperature. This paper presents a study of the phonon spectra and the specific heat associated with these phases. For Ne, two groove phases of different density are investigated, while for CH 4 two groove phases of different density and the ''three-stripe'' phase are studied. In addition, results from classical Monte Carlo simulations are presented which provide information about the thermodynamic behavior of different phases of CH 4 at higher temperatures; a dimensionality crossover is indicated by the presence of a distinctive peak in the specific heat.

Experimental low-temperature heat capacity of one-dimensional xenon adsorbate chains in the grooves of carbon c-SWNT bundles

“…He calculated the temperature dependencies of one-dimensional chains of inert gas adsorbates (Ar, Kr, Xe) in the interval 2-40 K [29]. Similar results on the heat capacity of the chains of Ne atoms and CH 4 molecules adsorbed physically in the grooves of c-SWNT bundles were obtained in a theoretical study [30].…”

“…There is good agreement between theoretical and experimental Debye temperatures of 1D Xe chains. The large discrepancy observed for Ne chains is somewhat surprising [28,30]. At T > 8 K the experimental curve C Xe (T) starts to exceed the theoretical one [29] and the C Xe (T) increases monotonously with the rising temperature.…”

“…Low temperature dynamics of inert gas atoms and methane molecules in c-SWNT bundles was considered in theoretical studies [29][30][31]. The calculated heat capacities of 1D chains of inert gas atoms and methane molecules adsorbed physically in the grooves of c-SWNT bundles are reported in [29] (Ar, Kr, Xe) and [30] (Ne, CH 4 ).…”

“…The calculated heat capacities of 1D chains of inert gas atoms and methane molecules adsorbed physically in the grooves of c-SWNT bundles are reported in [29] (Ar, Kr, Xe) and [30] (Ne, CH 4 ).…”

Thermodynamic properties and correlation functions of Ar films on the surface of a bundle of nanotubes

“…This is a higher temperature than some of the important structure in the heat capacity-the first peak in the heat capacity occurs at or below this temperature. Modifications to the heat capacity from quantum mechanics at very low energies are given by Debye theory: 18,48,49,50 we expect that c(T ) → 0 as T → 0, and c(T ) ∝ T d , where d ∼ 1 for the groove and d ∼ 2 for the monolayer, if the density is high enough to form a bulk phase. To evaluate quantum effects accurately would require application of the path integral Monte Carlo method to the problem.…”