Diameter selectivity of nanotube sidewall functionalization probed by optical spectroscopy

We present wide range optical spectroscopic measurements on sidewall functionalized HiPCO nanotubes. In the near infrared spectrum the peaks show fine structure where the separate peaks are related to nanotubes with different diameters. This gives us the opportunity to investigate the possible diameter dependence of the functionalization efficiency.We measured nanotube samples functionalized with butyl sidegroups in a wide frequency range, in the form of self‐supporting thin films. From the transmission spectrum optical conductivity was calculated by Kramers‐Kronig transformation and fitted by Drude – Lorentz oscillators. Comparing the results we show that the nanotubes with smaller diameters are affected more easily by functionalization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)