Optical properties of structurally sorted single-wall carbon nanotube
ensembles
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 244 (11):
3964-3968 (November 2007)21st International Winterschool on Electronic Properties of Novel
Materials, Kirchberg, AUSTRIA, MAR 10-17, 2007.DOI: {10.1002/pssb.200776195}
Abstract
Using density gradient ultracentrifugation and isopycnic fractionation
we structurally sort traditionally prepared single-wall carbon nanotube
suspensions, and show that fractions with photoluminescence (PL) quantum
yields of over 1\% can be isolated. Moreover, we find that traditionally
prepared suspensions appear to be composed of a significant fraction of
small nanotube aggregates which reduce the quantum yield of the
ensembles by a factor of 5 with respect to the most photoluminescent
fractions. In order to better understand the nature of the nonradiative
decay processes that lead to lower ensemble PL quantum yields, nanotube
ropes of diameter enriched tubes are made and compared with the
aforementioned ensemble measurements. Changes in the optical properties
are discussed in terms of energy transfer to metallic tubes,
carbonaceous particles, and smaller band gap tubes. (c) 2007 WILEY-VCH
Verlag GmbH & Co. KGaA. Weinheim.