Observation of Electronic Raman Scattering in Metallic Carbon Nanotubes
  We present experimental measurements of the electronic contribution to the Raman spectra of individual metallic single-walled carbon nanotubes (MSWNTs). Photoexcited carriers are inelastically scattered by a continuum of low-energy electron-hole pairs created across the graphenelike linear electronic subbands of the MSWNTs. The optical resonances in MSWNTs give rise to well-defined electronic Raman peaks. This resonant electronic Raman scattering is a unique feature of the electronic structure of these one-dimensional quasimetals. 
Hootan Farhat, St\'ephane berciaud, Martin Kalbac, Riichiro Saito,   Tony F. Heinz, Mildred S. Dresselhaus and Jing Kong
cond-mat.mes-hall