  In this work, phosphorous-doped single-walled carbon nanotubes have been
synthesized by the thermal decomposition of trimethylphosphine using a
high-vacuum chemical vapor deposition method. Furthermore, a modified
density-gradient-ultracentrifugation process has been applied to carefully
purify our doped material. The combined use of Raman and X-ray photoelectron
spectroscopy allowed us to provide the first insight into the bonding
environment of P incorporated into the carbon lattice, avoiding competing
signals arising from synthesis byproducts. This study represents the first step
toward the identification of the bonding configuration of P atoms when direct
substitution takes place.
