Article,
Effects of pressure on the structural and electronic properties of linear carbon chains encapsulated in double wall carbon nanotubes
CARBON, (2018)
DOI: 10.1016/j.carbon.2018.01.084
Abstract
High-pressure resonance Raman experiments were performed on linear carbon chains Cn confined in double-wall carbon nanotubes (Cn@DWCNT).
Our results indicate that the frequency of the chain mode undergoes a
non-linear decreasing as pressure increases, in agreement with previous
studies of the behavior of carbon chains into multi-wall carbon
nanotubes. After the pressure cycle, the Cn modes present an
irreversible frequency downshift together with an irreversible upshift
(downshift) of the RBM modes (Gthorn band) of the inner tube. These
spectral changes are interpreted as evidence of cross-linking between
the carbon chain and the wall of the inner tube. Density functional
theory (DFT) calculations were performed in order to shed light on the
interpretation of the experimental data. The theoretical calculations
show a pressure-induced charge transfer from the nanotube to the carbon
chain, thus resulting in an increasing of the C equivalent to C bond
length, and consequently, a softening frequency of the Cn Raman mode.
Furthermore, an irreversible cross-linking between the tube and Cn is
observed when the maximum applied pressure is higher than the pressure
of radial tube collapse is predicted by modelling, thus supporting the
experimental results. (C) 2018 Elsevier Ltd. All rights reserved.
