Temperature Dependence of Electron to Lattice Energy-Transfer in Single-Wall Carbon Nanotube Bundles

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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(Tₑ,Tₗ), the rate of energy-transfer between the electronic system and the lattice as a function of electron and lattice temperatures Tₑ and Tₗ. The experiments are consistent with a T⁵ 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/thetaD², where thetaD 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.