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Rakesh Voggu

Publications and source records attributed to Rakesh Voggu.

5 recordsLinked to original sources
arXiv2009

A New Method of Obtaining High Enrichment of Metallic Single-Walled Carbon Nanotubes

Arc-discharge with carbon electrodes containing Ni and Y2O3 in the presence of Fe(CO)5 vapors have been investigated. It is found that unlike the cathode deposit, the web deposited in the chamber contains mainly metallic single-walled carbon nanotubes (SWNTs) as evidenced from Raman and optical absorption spectroscopy. The percentage of metallic SWNTs increases with the concentration of Fe(CO)5. Under optimal conditions, the web contains over 90% of metallic SWNTs. This method enables the synthesis of nearly pure metallic SWNTs on a large scale.

cond-mat.mtrl-sci↗
arXiv2008

Effects of interaction of electron donor and accepter molecules on the electronic structure of graphene

Effects of interaction of graphene with electron donor and acceptor molecules have been investigated by employing Raman spectroscopy. The G band softens progressively with the increasing concentration of tetrathiafulvalene (TTF) which is an electron donor while the band stiffens with increasing concentration of tetracyanoethylene (TCNE) which is an electron-acceptor molecule. Both TTF and TCNE broaden the G-band. The 2D band position is also affected by interaction with TTF and TCNE. The intensity of the 2D-band decreases markedly with the concentration of either. The ratio of intensities of the 2D and G bands decreases with increase in TTF and TCNE concentrations. The electrical resistivity of graphene varies in opposite directions on interaction with TTF and TCNE. All these effects occur due to molecular charge-transfer, as evidenced by the observation of charge-transfer bands in the electronic absorption spectra.

cond-mat.mtrl-sci↗
arXiv2008

Semiconductor to metal transition in SWNTs caused by interaction with gold and platinum nanoparticles

Single-walled carbon nanotubes (SWNTs) have been coated with gold and platinum nanoparticles either by microwave treatment or by the click reaction and the Raman spectra of these SWNT-metal nanoparticle composites have been investigated. Analysis of the G bands in the Raman spectra shows an increase in the proportion of metallic SWNTs on attachment with metal nanoparticles. This conclusion is also supported by the changes observed in the RBM bands. Ab-initio calculations reveal that semiconductor-metal transition occurs in SWNTs due to Columbic charge transfer between the metal nanoparticles and the semiconducting SWNTs.

cond-mat.mtrl-sci↗