Eur. Phys. J. B 75, 115-120 (2010)
https://doi.org/10.1140/epjb/e2009-00374-1

Long lived photo excitations in (6, 5) carbon nanotubes

¹ IIT-Department of Physics, Politecnico di Milano, P.zza L. da Vinci 23, 20133 Milano, Italy
² Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Corresponding author: calogero.sciascia@mail.polimi.it

Received: 16 July 2009
Revised: 31 August 2009
Published online: 3 November 2009

Abstract

We study the photo-induced transmission change (ΔT/T) upon quasi-continuum laser excitation, for different modulation frequency and excitation intensity in films of (6, 5) enriched CoMoCat single wall nanotubes (SWNTs) embedded in a polymeric matrix. This technique probes long-lived excited species, with lifetime in the 1 ms–1 s domain. The observed line-shape of ΔT/T spectra that can be assigned to a superposition of ground state bleaching and absorption modulation. We speculate that photo-excitation creates charges which get trapped in the sample, acquiring ms lifetime. This causes bleaching of the ground state absorption due to state filling and possibly a tube diameter expansion, with consequent blue shift of the optical transition.