Insight into the mechanism of sidewall functionalization of single-walled nanotubes: an STM study

Understanding the chemistry of carbon nanotubes is a crucial step towards their ultimate practical use. Here we report the first nanoscale images of single wall nanotubes (SWNTs) whose sidewalls have been chemically derivatized. Scanning tunneling microscopy (STM) images of fluorinated SWNTs reveal a dramatic banded structure which indicates broad continuous regions of fluorination terminating abruptly in bands orthogonal to the tube axis. This pattern is consistent with an energetically favored addition mechanism where fluorine atoms add around the circumference of the tube. STM images of sparsely butylated SWNTs, for which fluorinated SWNTs served as precursor, are also reported.