The length-fractionation of shortened (250 to 25 nm), zwitterion-functionalized, single wall carbon nanotubes (SWNTs) has been demonstrated via gel permeation chromatography (GPC). The UV-Vis spectrum of each fraction indicates an apparent "solubilization", as evident by the direct observation of all predicted optically allowed interband transitions between the mirror image spikes in the density of states of both metallic and semiconducting SWNTs with various tube diameters. As evident by the presence or absence of the 270 nm, pi-plasmon absorption, this "solubilization" is a dynamic process and leads to re-aggregation if left undisturbed for a couple of weeks or upon dissociation of the pendant octadecylamine groups. This non-destructive and highly versatile separation methodology opens up an array of possible applications for shortened SWNTs in nanostructured devices.

Single-walled carbon nanotube (SWNT) density and bundle size has been controlled by a simple one step CVD growth process using a polyferrocenylsilane block copolymer as the pre-organized catalyst source.{ Electronic supplementary information (ESI) available: synthesis of PS-b-PFEMS, SWNT growth and characterization. See

High-throughput field-effect transistors ͑FETs͒ containing over 300 disentangled, high-purity chemical-vapor-deposition-grown single-walled carbon nanotube ͑SWNT͒ channels have been fabricated in a three-step process that creates more than 160 individually addressable devices on a single silicon chip. This scheme gives a 96% device yield with output currents averaging 5.4 mA and reaching up to 17 mA at a 300 mV bias. Entirely semiconducting FETs are easily realized by a high current selective destruction of metallic tubes. The excellent dispersity and nearly-defect-free quality of the SWNT channels make these devices also useful for nanoscale chemical and biological sensor applications.

Structural and chemical changes of aged terrace-like pentacene films have been investigated using grazingincidence X-ray diffraction (GIXD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The electrically active pentacene nanolayers on the dielectric substrate are susceptible to the oxidative degradation upon aging in air because the near-substrate grain boundaries between the terrace-like domains are well exposed to light and air during aging. GIXD and AFM for pentacene films have been used to elucidate the structural changes, locally initiated at the edges of terraced layers of pentane films upon aging-related oxidative degradation. XPS has revealed the chemical nature of pentacene oxidation upon aging, suggesting the development of hydroxyl and carbonyl groups during aging with light in air. Finally, we have investigated how the structural and chemical degradation of the aged pentacene films reduces the charge mobility and on-off ratio of organic field-effect transistors exposed to light and air.