Dimensional crossover and quantum effects of gases adsorbed on nanotube bundles

TL;DR

This paper investigates the adsorption behavior of gases on carbon nanotube bundles, exploring dimensional crossover, quantum effects, and phase transitions through simulations and theoretical models, with comparisons to experimental data.

Contribution

It introduces a combined classical and quantum modeling approach to study gas adsorption on nanotubes, revealing a second layer groove phase and thermal property evolution.

Findings

Identification of a second layer groove phase

Observation of dimensional crossover from 1D to 2D behavior

Quantum corrections significantly affect adsorption properties

Abstract

Adsorption properties of several gases (Ne, CH4, Ar, Xe) on the external surface of a carbon nanotube bundle are investigated. Calculations are performed at low coverage and variable temperature, and for some temperatures as a function of coverage. Within a simple model (in the limit of very low coverage) we are able to study the evolution of the film's thermal properties from those of a one dimensional (1D) fluid to those of a 2D film. In addition, grand canonical Monte Carlo simulations are performed in order to identify a second layer groove phase, which occurs once a monolayer of atoms covers the external surface. We derive from the simulations the isosteric heat, compresibility and specific heat as a function of coverage. We evaluate alternative models in order to derive quantum corrections to the classical results. We compare our findings with those of recent adsorption experiments.