AVS 54th International Symposium | |
Nanometer-scale Science and Technology | Thursday Sessions |
Session NS-ThM |
Session: | Nanotube Devices and Processes |
Presenter: | Z.T. Wang, Trinity College Dublin, Ireland |
Authors: | Z.T. Wang, Trinity College Dublin, Ireland P.M. Ryan, Trinity College Dublin, Ireland N.P.P. Niraj, Trinity College Dublin, Ireland J.J. Boland, Trinity College Dublin, Ireland |
Correspondent: | Click to Email |
The most common processing technique for carbon nanotubes involves dispersing them in a liquid media. However, due to their high molecular weight, nanotubes suspend and are not soluble in all known solvents. Usually, surfactants are used to overcome this obstacle.1 Recently people found that pristine single wall carbon nanotubes can be spontaneously dispersed and even exfoliated in an N-methyl-pyrrolidone (NMP) solvent, forming a carbon nanotube solution.2 The negative free energy of mixing NMP with nanotubes leads to the strongly adsorption of a huge number of NMP molecules on the nanotubes in NMP solution and even dried-powder. In our experiments, carbon nanotubes processed by the NMP solvent are deposited on clean Si(001) substrates using a dry deposition method3 and investigated using an ultrahigh-vacuum (UHV) scanning tunneling microscope (STM). We find that NMP molecules diffuse from the nanotubes and become irreversibly chemically adsorbed on Si(001) surfaces due to the strong interaction of nitrogen with Si dangling bonds, indicating NMP molecules remain bound to nanotubes even under UHV conditions. However a few remaining molecules reversibly bound to the nanotubes are observed using STM and are seen to emerge from tube bundles. The molecules can migrate on the bundles during imaging and finally become bound to the Si(001) substrate. After all NMP molecules are removed, there is no defect left on the nanotubes.
1 G. S. Duesberg et al, Chemical Communications, 435 (Feb, 1998)
2 S. D. Bergin et al, unpublished.
3 P.M. Albrecht and J. W. Lyding, App. Phys. Lett. 83, 5029 (2003).