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We have investigated the growth process of carbon nanotubes in carbon nanotubes as a function of anihilation temperature and duration. Raman spectroscopy is applied to characterize the produced DWCNTs. The RBM scales as l/d and renders the very narrow new inner CNTs easily detectable. We found a dramatic decrease of the fullerene concentration in the samples before the inner CNTs start to emerge. The growth of the new inner CNTs starts with the smallest diameter nanotubes, before it is uniformly extended to all possible diameters. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We performed vapor phase filling of SWCNTs with various kinds of fullerenes. C60, C70, 13C enriched C60 and mixtures of these were used. The resulting peapods as well as the DWCNTs obtained by annealing were characterized with multi frequency Raman spectroscopy. Simultaneous filling with C60 and C70 was found to take place with the same efficiency. When using the 13C enriched C60 for DWCNT synthesis, mode softening for all inner shell lines was observed, while the outer shell response remained unchanged. The yield of inner shell CNTs is almost the same for C60 and C70 except that C70 is very inefficient in forming mid diameter inner CNTs with RBM frequencies close to 365 cm-1. If inner CNTs are grown from mixed peapods of C70 and 13C enriched C60 these particular CNTs are mainly built from C60. This is confirmed by the observation of distinct line shifts in the inner shell RBM. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

By annealing fullerene peapods at high temperatures in a dynamic vacuum it is possible to produce double-wall carbon nanotubes. A Raman investigation revealed that the inner single-wall carbon nanotubes are remarkably defect free showing very strong and very narrow radial breathing modes (RBMs). The number of observed RBMs is larger than the number of geometrically allowed inner tubes. This splitting is caused by the interaction of one type of inner tube with several types of outer tubes the inner tube may grow in. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Double wall carbon nanotubes (DWNTs) were derived from peapods by annealing at high temperature. We report on the Raman response of the RBM of the inner tubes. As a consequence of their small diameter the Raman spectra of the inner components of the DWNTs show well distinguishable RBM lines of the different inner tubes, besides the usual response from the outer tubes. The evaluation of these spectra has led to a full assignment of the chiral vectors to the spectroscopic lines. We found vRBM = 235.5/d + 13.8 · d ,v in cm-1, d in nm. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Double walled carbon nanotubes were derived from C60 peapods by annealing at 1280 °C for 2 hours in a dynamic vacuum. Resonance Raman spectroscopy was used to investigate the resulting tube systems. The spectral range of the radial breathing mode of the inner shell nanotubes was found to consist of well separated narrow lines. From the 41 geometrically allowed tubes between 250 and 470 cm-1 36 were identified. The observed number of lines was more than two times the number of allowed tubes. This effect is found to be due to a splitting of all Raman lines into doublets or triplets. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recently, it was possible to fill single wall carbon nanotubes with C[SUB60] fullerenes resulting in carbon structures with new and interesting properties (so-called C[SUB60] peapods). All Raman allowed modes of the free C[SUB60] were identified for the encaged C[SUB60]. In this contribution we demosntrate how the concentration of the peas in the SWCNT pods can be obtained from a detailed analysis of the Raman spectra of the peapods. [ABSTRACT FROM AUTHOR]