We have experimentally determined the binding energies of Xe, ${\mathrm{CH}}_4$, and Ne on samples of closed-ended single-wall nanotube (SWNT) bundles. We find values for these quantities which are larger by approximately $75\%$ on the SWNT samples than the values found for the same adsorbates on planar graphite. We have also determined the monolayer capacity of a SWNT sample using Xe and Ne adsorption. A comparison of all of our results leads us to conclude that none of the gases studied adsorb on the interstitial channels in the SWNT bundles.

• Received 21 March 2000

DOI:https://doi.org/10.1103/PhysRevLett.85.138