Time-Domain Ab Initio Studies of Phonon-Induced Relaxation of Electronic Excitations in Carbon Nanotubes

Electron-phonon interactions in carbon nanotubes (CNT) determine response times of optical switches and logic gates, the extent of heating and energy loss in CNT wires and field-effect transistors, and even a mechanism for CNT superconductivity. Numerous time-resolved experiments have revealed intriguing features of the electron-phonon relaxation in CNTs in response to external stimuli. We report the ab initio studies of the relaxation performed in real-time, directly mimicking the experimental data. The results reveal a number of unexpected features of the relaxation processes, including the differences between the intraband relaxation and electron-hole recombination, the photoexcitation energy dependence of the relaxation, the importance of defects, the dependence on the excitation intensity, and a detailed role of active phonon modes. \newline \newline [1] B. F. Habenicht, C. F. Craig, O. V. Prezhdo, ``Electron and hole relaxation dynamics in a semiconducting carbon nanotube'', \textit{Phys. Rev. Lett.} \textbf{96} 187401 (2006); \textit{Virtual J. Nanoscale Sci. {\&} Tech,} May 29, 2006; \textit{Virtual J. of Ultrafast Science}, June 2006