Desorption kinetics and interaction of Xe with single-wall carbon nanotube bundles

TL;DR

This study investigates xenon desorption from single-wall carbon nanotube bundles using thermal desorption spectroscopy, revealing higher binding energies compared to graphite and identifying adsorption in groove-sites.

Contribution

The paper introduces a coupled desorption-diffusion model to determine Xe binding energies on SWNT bundles, highlighting the role of groove-site adsorption.

Findings

Xe binding energy on SWNT bundles is 27 kJ/mol.

Desorption peaks are broader and at higher temperatures than graphite.

Adsorption occurs in highly coordinated groove-sites.

Abstract

We present a study on the kinetics of xenon desorption from single-wall carbon nanotube (SWNT) bundles using thermal desorption spectroscopy (TDS). TD-spectra from SWNT samples show a broad desorption feature peaked at significantly higher temperature than the corresponding low-coverage desorption feature on graphite. The observations are explained using a coupled desorption-diffusion (CDD) model, which allows the determination of the low-coverage Xe binding energy for adsorption on SWNT bundles, 27 kJ/mol. This energy is about 25% higher than the monolayer binding energy on graphite, 21.9 kJ/mol. By comparison with molecular mechanics calculations we find that this increase of the binding energy is consistent with adsorption in highly coordinated groove-sites on the external bundle surface.