In this paper the environmental effects on the vibrational properties of individual carbon nanotubes were studied by means of Raman spectroscopy. The individual nanotubes were first synthesized by catalytic chemical vapour depositon method. Then their geometric structure was determined by electron diffraction and high-resolution electron microscopy. The intrinsic experimental relationship between RBM frequency and the tube diameter was obtained and certain deviations from the expected 228/d relationship were found. The effect of the substrate was identified as the most probable explanation for these experimental observations. In order to quantify the origins of deviations, we propose a comparison between our experimental data and calculations performed in the framework of elasticity theory.
Keywords: individual carbon nanotubes, Raman spectroscopy, radial breathing modes, environmental effects
In this paper a method for the atomic structure analysis of single-walled and multi-walled carbon nanotubes based on the combination of Raman spectroscopy and electron diffraction is presented. We discuss the main criteria of this method and give an example of index-assignment of individual double-walled carbon nanotube. We argue that the combination of several techniques gives the most accurate and unambigous structure identification.
Keywords: individual carbon nanotubes, Raman spectroscopy, electron diffraction, electron microscopy
In this paper a systematic study of individual single-walled and multi-walled carbon nanotubes was performed by Raman spectroscopy and high-resolution electron microscopy. We have presented the geometrical and electronic structure analysis on the examples of two tubes: individual single-walled and double-walled nanotubes. The role of different environmental effects and their influence on the final structure assignment are discussed. Moreover, we have shown that the Raman spectroscopy gives reliable estimations of the nanotube diameters and the conductivity. Given a non-destructible character of Raman spectroscopy, we may conclude that it is one of the most efficient methods for structure analysis of carbon nanotubes.
Keywords: Carbon nanotubes, Raman spectroscopy, electron microscopy
In this work we have investigated the structure of individual single-walled and multi-walled carbon nanotubes by high-resolution electron microscopy and electron diffraction. To grow carbon nanotubes we used a catalytic chemical vapor deposition method. It was shown, that this synthesis protocol gave in general single-walled and double-walled carbon nanotubes with a high level of crystallinity. The diameters of the nanotubes were in the range 1.5 - 7 nm. We also observed that there was a certain level of amorphous carbon deposited on the nanotube surface during the growth. In this work we also present the structure analysis of the double-walled carbon nanotube by means of electron diffraction. We show that the structural date derived from electron microscopy and electron diffraction agree within the experimental error.
Keywords: Carbon nanotubes, electron diffraction, electron microscopy