Robin Nicholas

Abstract:

A change in the relative abundance of single-walled carbon nanotubes, due to the presence of both nitrogen and boron during synthesis, has been identified through Raman and absorption spectroscopy. Raman spectroscopy shows that for two specific branches boron mediates the growth of smaller-diameter zigzag or near-zigzag nanotubes. We combine our experimental results with an improved Kataura model to identify two of the preferentially grown species as (16,0) and (14,1). © 2005 The American Physical Society.

Abstract:

Encapsulation of organic molecules in carbon nanotubes has opened a new route for the fabrication of hybrid nanostructures. Here we show that diameter-selective encapsulation of two metallocene compounds bis(cyclopentadienyl) cobalt and bis(ethylcyclopentadienyl) cobalt has been observed in single-walled carbon nanotubes. In particular, bis(cyclopentadienyl) cobalt is observed to fill only nanotubes of one specific diameter. Electron transfer from the cobalt ions to the nanotubes has been directly observed through a change in the charge state of the encapsulated molecules. The filling of the tubes is found to induce a red-shift of the photoluminescence emission, which is attributed to the formation of localized impurity states below the conduction band of the nanotubes.