| Abstract
| - Single-wall carbon nanotubes (SWNTs) were oxidatively functionalized by nitric acid treatment. The presenceof carboxyl groups was proven by IR spectroscopy, matching earlier IR and NMR observations. Ramanspectra in the radial breathing mode (RBM) and G line spectral windows were measured with six laser linesranging from 457 to 647 nm. The RBM mode was observed to upshift by the functionalization with verylittle change in the spectral line shape. By the analysis of the spectral moments of the lines, this upshift isinterpreted as a change in an empirical intertube interaction function. In agreement with previous TEM results,we have found that bundles in a pristine SWNT sample are significantly thinner (<10 tubes) than those inthe oxidized samples (>30 tubes). Changes observed in solvatation properties and sample morphology couldbe explained on this basis. Our observations suggest that carboxyl related secondary bonding forces mightalso play a role in the stacking of oxidized SWNTs.
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