Phase stability of doped carbon nanotubes

This report presents spectroscopic probes of intercalation processes in single walled carbon nanotubes. Before saturation doping of alkali metals (KC x , x∼9), we found a rather stable intermediate phase KC 27 . where the Raman active E 2g mode shows an anomalous hardening. Considering the close correlation with the graphite intercalation compounds, we postulate that in KC 27 phase, alkali ions are inserted between two tubes rather than the hollow site surrounded by three tubes.