The nanohorn samples were characterized with electron microscopy and Raman spectroscopy. The Raman spectra show characteristic peaks attributable to the D and G-bands, with the G-band exhibiting a shoulder in contrast to a single Lorentzian peak reported in the literature.

The NC-SWNHs were either used in as-produced condition; or, they were treated with methanol and sonicated, and then heated at 333 K under vacuum; or, they were heat-treated at 520 K under vacuum. Full adsorption isotherms were measured at temperatures between 22 and 31 K on as-produced and treated NC-SWNH samples. Low coverage isotherms, for binding energy determinations, were measured between 40 and 49 K on the methanol treated NC-SWNHs.

Adsorption studies were also conducted on as-produced and treated NEC/JST-SWNH samples. Treatments on NEC/JST-SWNH samples include vacuum annealing at 520 K, and, first oxidizing and then annealing under vacuum at 520 K.

The results obtained on the different sets of samples will be contrasted and compared.

Values for the effective specific surface areas, isosteric heats, and binding energies will be presented.

This work was supported by the NSF grants DMR-008 9713 and DMR-0104176.