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Investigation of fullerene encapsulation in carbon nanotubes using a complex approach based on vibrational spectroscopy
Author(s) -
Botos Ákos,
Khlobystov Andrei N.,
Botka Bea,
Hackl Rudi,
Székely Edit,
Simándi Béla,
Kamarás Katalin
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201000375
Subject(s) - fullerene , high resolution transmission electron microscopy , raman spectroscopy , carbon nanotube , materials science , spectroscopy , nanotube , molecule , adsorption , nanotechnology , analytical chemistry (journal) , transmission electron microscopy , chemistry , organic chemistry , optics , physics , quantum mechanics
For carbon nanotubes filled with fullerenes (“peapods”), it is a key issue to find an analytical method that distinguishes the molecules inside the nanotube from those adsorbed on its surface. High‐resolution transmission electron microscopy (HRTEM) detects both encapsulated and adsorbed molecules which are large enough ( e.g ., fullerenes), but being a local‐probe method, it cannot be applied to large amounts of sample. In Raman spectroscopy, the empirical rules for line shifts and splitting are nanotube‐type dependent and often ambiguous. We prepared C 60 peapods by nano‐extraction using supercritical CO 2 as a solvent, and subsequently removed the adsorbed fullerene molecules by washing the samples. We analyzed the samples by the combination of HRTEM, Raman, and midinfrared attenuated total reflectance (MIR‐ATR) spectroscopy. Although the TEM images proved that the nanotubes were filled with fullerenes, we did not observe any shift in the fullerene's A g (2) Raman mode compared to C 60 crystals. ATR spectra, on the other hand, were found to detect only the adsorbed molecules. Therefore, the combination of the two methods provide good basis for determining the success of nanotube filling by spectroscopy alone.