Resonance Raman study of polyynes encapsulated in single-wall carbon nanotubes

Abstract

This work presents a resonance Raman study of polyyne molecules (linear carbon chains) encapsulated inside single-wall carbon nanotubes using many different laser lines. A strong enhancement of the polyyne Raman features is observed around $2.1\mathrm{eV}$, and this result is ascribed to dark electronic transitions of the linear carbon chains that can be observed when they are trapped inside a carbon nanotube. The huge observed energy splitting between bright and dark excited states is ascribed to strong Coulomb effects in this strictly one-dimensional system.