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Doping of C 60 Fullerene Peapods with Lithium Vapor: Raman Spectroscopic and Spectroelectrochemical Studies
Author(s) -
Kalbáč Martin,
Kavan Ladislav,
Zukalová Markéta,
Dunsch Lothar
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701863
Subject(s) - raman spectroscopy , doping , lithium (medication) , materials science , fullerene , analytical chemistry (journal) , chemistry , optics , optoelectronics , organic chemistry , physics , endocrinology , medicine
Raman spectroscopy and in situ Raman spectroelectrochemistry have been applied to the study of the lithium vapor doping of C 60 @SWCNTs (peapods; SWCNT=single‐walled carbon nanotube). A strong degree of doping was proven by the disappearance of the radial breathing mode (RBM) of the SWCNTs and by the attenuation of the tangential (TG) band intensity by two orders of magnitude. The lithium doping causes a downshift of the A g (2) mode of the intratubular C 60 by 27 cm −1 and changes the resonance condition of the encapsulated fullerene. In contrast to potassium vapor doping, the strong downshift of the TG band was not observed for lithium doping. The peapods treated with lithium vapor remained partially doped even when they were exposed to humid air. This was reflected by a reduction in the intensity of the nanotube and the fullerene modes and by the change in the shape of the RBM band compared with that of the undoped sample. The A g (2) mode of the intratubular fullerene was not resolved after contact of the lithium‐doped sample with water. Lithium insertion into the interior of a peapod and its strong interaction with the intratubular fullerene is suggested to be responsible for the air‐insensitive residual doping. This residual doping was confirmed by in situ spectroelectrochemical measurements. The TG band of the lithium‐doped peapods did not undergo an upshift during the anodic doping, which points to the formation of a stable exohedral metallofullerene peapod.