Relaxation dynamics of carbon nanotubes of enriched chiralities

Abstract

In our work we combined experimental and theoretical investigations of the relaxation dynamics of the single wall carbon nanotubes (SW-CNTs) in solution samples with enriched chiralities of (7,5) and (7,6) species. In two-color pump-probe studies we observe three-exponential decay in the differential transmission spectra in the range of few picoseconds, tens of picoseconds, and hundreds of picoseconds. Decay curves are very similar for both SW-CNT chiralities under resonant excitation and probing of excited and ground state transition energies, respectively. Both types of tubes exhibit no changes in decay for the different excitation energies in the range ±50meV around the excited state. By tuning the probe pulse towards energies higher then ground state (up to +350meV) we observe acceleration of the first decay component from 5.8ps down to 1.6ps. Our experimental results are supported by time resolved microscopic calculations based on carbon nanotube Bloch equations proving the fast decay component behavior being dominated through scattering with acoustic phonons.