Edward T. Mickelson

Fluorination of single-wall carbon nanotubes

Abstract Purified single-wall carbon nanotubes (SWNTs) were fluorinated at several different temperatures. Product stoichiometries were determined and electron microscopy was used to verify whether or not the fluorination was destructive of the tubes. SWNTs fluorinated at three different temperatures were then defluorinated using hydrazine. Raman spectroscopy and resistance measurements were utilized to verify whether or not the products of the defluorination were in fact SWNTs. It has been determined that the bulk of the SWNTs survive the fluorination process at temperatures up to 325°C and that hydrazine can be employed as an effective defluorinating agent to regenerate the unfluorinated starting material.

Reversible sidewall functionalization of buckytubes

Abstract Single-wall fullerene nanotubes have been made soluble in various organic solvents, including chloroform, methylene chloride, and tetrahydrofuran by covalently attaching alkanes to their sidewalls. Sidewall-alkylated nanotubes are obtained by reacting sidewall-fluorinated nanotubes with alkyl magnesium bromides in a Grignard synthesis or by reaction with alkyllithium precursors. Covalent attachment to the sidewalls was confirmed by UV–visible spectroscopy, which is also used to show that the alkane sidewall groups can be removed by oxidizing them in air to recover pristine nanotubes.

Dissolution of small diameter single-wall carbon nanotubes in organic solvents?

The solubility of small diameter single-wall carbon nanotubes in several organic solvents is described, and characterization in 1,2-dichlorobenzene is reported.

INSIGHT INTO THE MECHANISM OF SIDEWALL FUNCTIONALIZATION OF SINGLE-WALLED NANOTUBES : AN STM STUDY

Abstract 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.

Methylated and phenylated C60 from fluorinated fullerene precursors

Abstract C 60 has been fluorinated with F 2 to yield a product which consists mostly of C 60 F 44 . This species was then reacted with methyl and phenyl lithium reagents to yield the respective methylated and phenylated nucleophilic substitution products. These products have been confirmed and characterized by IR, 1 H -NMR and mass spectroscopies.

Adsorption of Fluorinated C60 on the Si(111)-(7?7) Surface Studied by Scanning Tunneling Microscopy and High-Resolution Electron Energy Loss Spectroscopy

The adsorption structure of fluorinated C60 molecules deposited on the Si(111)-(7×7) surface was studied using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). The results of HREELS revealed the existence of the silicon-fluorine vibration modes with the energy of 103–107 meV, indicating that some of the fluorine atoms were detached from the molecules and chemisorbed to the surface. These fluorine adsorption sites were observed around the adsorbed molecules directly in the STM images. Many of the fluorine-adsorbed sites were found to form thread-like structures. Random formation of the F–Si bonds on the surface prohibits the fluorinated fullerenes freedom from forming an ordered monolayer on the Si(111)-(7×7) surface.

Fluorinated fullerene thin films grown on the Si(1 1 1)-7 × 7 surfaces : STM and HREELS investigations

Thin layers of the C 60 F x molecules on the Si(1 1 1)-7 × 7 surface were investigated using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). Experimental results indicate that the fluorine atoms can detach from C 60 F x molecules and adsorb on the Si surface even at room temperature, which makes the surface chemically inert by formation of a strong Si-F bond. At the initial adsorption stage, the C 60 F x molecules may release fluorine atoms either due to the rocking motion of trapped molecules or during their migration (rolling) on the Si surface. The diffusion of fluorine on the Si(1 1 1)-7 × 7 surface and the initiation of etching in the areas of the highest fluorine concentration at lower temperature (∼300°C) than that for isolated fluorine sites, as well as coverage dependent step and terrace etching at higher temperatures, were also observed.

Fluorinated fullerene thin films on Si(111)-(7×7) surface

Thin layers of the C 6 0 F x molecules on the Si(111)-(7 x 7) surface have been investigated using scanning tunneling microscopy and high-resolution electron energy loss spectroscopy. The latter measurements indicated thatthe fluorine atoms are detached from C 6 0 F x molecules and adsorb on the Si surface even at room temperature. The C 6 0 F x molecules may release all fluorine atoms, either due to the oscillating motion of a trapped molecule or during their migration (rolling) on the Si surface. The diffusion of fluorine on the Si(111)-(7 x 7) surface and the initiation of etching in the areas of the higher fluorine concentration were observed at the lower temperature (∼300 °C) than that at isolated fluorine sites.