Nanotube Coalescence‐Inducing Mode: A Novel Vibrational Mode in Carbon Systems

Abstract

A resonant Raman mode located at 1855 cm−1 is related to vibrations of linear carbon chains and observed as a precursor to the merging of highly purified double-walled carbon nanotubes (DWNTs, see figure). This mode, termed the “coalescence-inducing mode” (CIM), which initiates the coalescence process, is induced by thermal annealing and its effect is enhanced by boron doping. The CIM mode arises from the generation of short 1D carbon chains (e.g., 3–7 atoms long) established covalently between adjacent tubes.