Showing papers by "S. Roth published in 1998"
TL;DR: In this article, changes in the electronic structure of multiwalled nanotubes due to the introduction of boron in the lattice are identified using scanning tunneling spectroscopy.
Abstract: Changes in the electronic structure of multiwalled nanotubes due to the introduction of boron in the lattice are identified using scanning tunneling spectroscopy. Doped tubes are metallic with no apparent band gap, in contrast to undoped tubes with varying electronic character. Combined with ab initio calculations, we show that changes in the local density of states, as determined from tunneling spectroscopy, must be interpreted in terms of nanodomains of dopant islands and not as isolated substitutional species.
273 citations
TL;DR: In this paper, an efficient purification of single-wall carbon nanotubes (SWNTs) using size exclusion chromatography (SEC) applied to surfactant stabilised dispersions of SWNT raw material is reported.
Abstract: The efficient purification of single-wall carbon nanotubes (SWNTs) is reported. Carbon nanospheres, metal particles, and amorphous carbon could be successfully removed by size exclusion chromatography (SEC) applied to surfactant stabilised dispersions of SWNT raw material. In addition, length separation of the tubes was achieved. The SWNTs obtained can be adsorbed in high densities onto chemically modified substrates. As determined by AFM investigations. the purified material consists of about equal fractions of both individual SWNTS and ropes of SWNTs.
205 citations
TL;DR: In this paper, the Young modulus of single-walled carbon nanotubes (SWNTs) was estimated based on the scanning force microscopy (SFM) cross sectional analysis of an individual MWNT (8 nm diameter).
Abstract: We report the controlled adsorption of individual multi- and single-walled carbon nanotubes from purified aqueous dispersions onto chemically modified silicon oxide surfaces as well as on predefined electrode patterns (100 nm electrode separation). Detailed structural investigations were performed using scanning force microscopy (SFM) without interference from other carbon materials. These studies revealed the striking flexibility of single-walled nanotubes. In contrast to comparably stiff multi-walled nanotubes (MWNTs) which bridged the electrode lines, single-walled nanotubes (SWNTs) were found to follow the profile of the underlying electrodes almost exactly. Based upon the SFM cross sectional analysis of an individual MWNT (8 nm diameter) a Young modulus of about 1 TPa was estimated. Furthermore, nanotube adsorption from the surfactant-stabilized dispersions led to flow-induced orientation processes.
72 citations
TL;DR: In this article, the spatial homogeneity of electronic properties, as evidenced by the local density of states (LDOS) of pure and B-doped multi-walled carbon nanotubes, was investigated using scanning tunneling microscopy and tunneling spectroscopy.
23 citations
TL;DR: In this article, a supramolecular synthesis utilizing perhydrotriphenylene (PHTP) as an inclusion host compound has proven to be an efficient method of aligning guest nonlinear optical (NLO) molecules in a parallel fashion.
Abstract: A supramolecular synthesis utilizing perhydrotriphenylene (PHTP) as an inclusion host compound has proven to be an efficient method of aligning guest nonlinear optical (NLO) molecules in a parallel fashion. Application of Markov's theory of stochastic processes explains successfully the experimentally observed spontaneous formation of polarity on a macroscopic level.
17 citations
TL;DR: In this paper, the lateral electrode lines separated by about 150 nm were connected by isolated chains of closely arranged 10-nm gold colloidal particles, and the electrodes were bridged by a polymer with attached thiol groups.
Abstract: Lateral electrode lines separated by about 150 nm were connected by isolated chains of closely arranged 10-nm gold colloidal particles. Prior to gold particle adsorption, the electrodes were bridged by a polymer with attached thiol groups. Elongation of the polymer strands during adsorption was achieved via flow effects exerted by a receding meniscus or application of an electric field perpendicular to the electrode array.
12 citations
01 Jan 1998
TL;DR: In this paper, the lateral electrode lines separated by about 150 nm were connected by isolated chains of closely arranged 10-nm gold colloidal particles, and the electrodes were bridged by a polymer with attached thiol groups.
Abstract: Lateral electrode lines separated by about 150 nm were connected by isolated chains of closely arranged 10-nm gold colloidal particles. Prior to gold particle adsorption, the electrodes were bridged by a polymer with attached thiol groups. Elongation of the polymer strands during adsorption was achieved via flow effects exerted by a receding meniscus or application of an electric field perpendicular to the elec- trode array.
9 citations
TL;DR: In this article, the density of states of pure carbon nanotubes and of boron doped nano-graphs has been determined from scanning tunneling spectroscopy.
5 citations
TL;DR: In this article, a few monolayer Langmuir-Blodgett (LB) films of a polymer that contains mercapto functions in the hydrophilic head group region were deposited on microstructured gold electrodes.
5 citations
TL;DR: In this paper, a polymer Langmuir film matrix was used for TEM analysis of gold clusters with core diameters in the region of 1-3 nm and the size distribution of the clusters was affected by thiol addition to the sub-phase leading to smaller particles with a decreased size variation.
3 citations
TL;DR: In this paper, the self-assembly of cyanine dye molecules was studied by scanning tunneling microscopy on chemically modified surfaces of highly oriented pyrolytic graphite and gold-coated mica.