We investigate the purification of as-prepared single wall carbon nanotubes (SWCNTs) by exposure to pulsed 193 and 248 nm laser light, as well as lamp wavelengths of 254 and 185 nm. Raman spectroscopy before and after laser exposure indicates the removal of non-nanotube material without modification of the distribution of tube diameter for material exposed to a 248 nm laser, while 193 nm laser light does not selectively oxidize carbon impurities. The mechanism of purification is further considered in the context of atmosphere (oxygen, ozone, nitrogen or partial vacuum) and temperature (measured average and calculated maximum). A mathematical model for pulsed laser heating is used to estimate the maximum temperature achieved during laser excitation. We attribute the purification of nanotube samples to photophysical interactions of the pulsed 248 nm photons in resonance with sp2 carbon.
Citation: Journal of Physical Chemistry B
Pub Type: Journals
carbon nanotube, excimer laser