Article,
Length-dependent optical effects in single walled carbon nanotubes
JOURNAL OF PHYSICAL CHEMISTRY B, 112 (19): 6211-6213 (May 2008)
DOI: {10.1021/jp077144l}
Abstract
Recently, Heller et al. reported length-dependent effects on the
relative photoluminescence (PL) quantum yield of single walled carbon
nanotubes (SWNTs) Heller et al J. Am. Chem. Soc. 2004, 126,
14567-14573. We propose a simple model involving thermal diffusion of
excitons along the nanotube axis and quenching at the ends, to explain
the observed trend in their data. By fitting to our model, we extract a
diffusion coefficient of 6 cm(2)/s for excitons in SWNTs. Assuming a
mono exponential decay of exciton PL, we also predict that effective
length-dependent PL lifetimes for these excitons lie in the range of 1 -
27 ps. Experimental observations are shown to be consistent with
stochastic rather than wavepacket-like exciton migration, which is in
agreement with ultrafast excitonic dephasing. Edge effects seem to limit
the use of short SWNTs in imaging and optical sensing applications.
