We applied Time-Resolved Two-Photon Photoemission spectroscopy to probe the electron- phonon (e-ph) coupling strength in double-wall carbon nanotubes. The e-ph energy transfer rate G(Te,Tl) from the electronic system to the lattice depends linearly on the electron (Te) and lattice (Tl) temperatures for Te>{ \Theta}Debye. Moreover, we numerically solved the Two-Temperature Model. We found: (i) a Te decay with a 3.5 ps time constant and no significant change in Tl; (ii) an e-ph coupling factor of 2x10^16 W/m3; (iii) a mass-enhancement parameter, { \lambda}, of (5.4=+/- 0.9)x10e-4; and (iv) a decay time of the electron energy density to the lattice of 1.34+/-0.85 ps.
Categories: cond-mat.mtrl-sci