Gas storage in single-walled carbon nanotubes

X-ray diffraction (XRD) and electrical resistance measurement on single-wal led carbon nanotube (SWNT) samples prepared by the are-discharge method are reported. The XRD profile of heat-treated sample indicated that air (oxyge n, and/or nitrogen and/or water) can be condensed inside the SWNTs. We also found that the electrical resistance of SWNT soot is significantly affecte d by exposing to the oxygen gas and humid air.