Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work...Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work focuses on the modification of the pulsed laser vaporization(PLV)technique to selectively produce certain carbon nanotube structures.Nanotube nuclei were“warmed-up”with an additional laser pulse,timed to coincide approximately with the nucleation event.The effect of the second laser on the carbon vapor temperature was studied by emission spectroscopy.Nanotube type populations with and without warm-up were compared by means of absorption,photoluminescence,and Raman spectroscopy.It was found that the warm-up of nanotube nuclei with a laser pulse has a noticeable,albeit small,effect on the nanotube population.The intensity of spectral features associated with(9,7)nanotube and its large chiral angle neighbors increased,while small chiral angle nanotubes decreased,with exception of the(15,0)tube.This experiment demonstrates that nanotube population during PLV synthesis can be manipulated in a controlled fashion.展开更多
基金The authors would like to acknowledge financial support from NASA under contract#NNJ05HI05C and from State of Texas,Space Act Agreement#SAA-AT-07-021(RAN 0798)(UTA07-099).The authors thank Dr.R.Bruce Weisman and Saunab Ghosh of Rice University for help with photoluminescence measurements.
文摘Many potential applications of carbon nanotubes are expected to benet from the availability of single-walled carbon nanotube materials enriched in metallic species,and specifically armchair nanotubes.The present work focuses on the modification of the pulsed laser vaporization(PLV)technique to selectively produce certain carbon nanotube structures.Nanotube nuclei were“warmed-up”with an additional laser pulse,timed to coincide approximately with the nucleation event.The effect of the second laser on the carbon vapor temperature was studied by emission spectroscopy.Nanotube type populations with and without warm-up were compared by means of absorption,photoluminescence,and Raman spectroscopy.It was found that the warm-up of nanotube nuclei with a laser pulse has a noticeable,albeit small,effect on the nanotube population.The intensity of spectral features associated with(9,7)nanotube and its large chiral angle neighbors increased,while small chiral angle nanotubes decreased,with exception of the(15,0)tube.This experiment demonstrates that nanotube population during PLV synthesis can be manipulated in a controlled fashion.
