Temperature dependence of electron-to-lattice energy transfer in single-wall carbon nanotube bundles

The electron-phonon coupling strength in single-wall carbon nanotube (SWNT) bundles has been studied directly in the time domain by femtosecond time-resolved photoelectron spectroscopy. We have measured the dependence of H(T-theta,T-I), the rate of energy transfer between the electronic system and the lattice as a function of electron and lattice temperatures T-theta and T-I. The experiments are consistent with a T-5 dependence of H on the electron and lattice temperatures, respectively. The results can be related to the e-ph mass enhancement parameter lambda. The experimentally obtained value for lambda/Theta(D)(2), where Theta(D) is the Debye temperature, suggests that e-ph scattering times at the Fermi level of SWNT bundles can be exceptionally long, exceeding 1.5 ps at room temperature.