The exfoliation of SWCNT bundles examined by simultaneous Raman scattering and photoluminescence spectroscopy

Simultaneous measurements of Raman scattering and photoluminescence (PL) prove to be a powerful method for quantifying the bundling states of single-walled carbon nanotube (SWCNT). This paper presents physical analysis and experimental evidence to establish that the G-band normalized photoluminescence, which is determined from the simultaneously acquired Raman scattering and PL emission spectra, can serve as a good indicator for quantifying the degree of exfoliation of SWCNT dispersions. without introducing the complications of sampling geometry and instrumental correction, this indicator directly relates to the intrinsic physical properties of a given SWCNT sample, namely, the absorption cross-section, differential Raman scattering cross-section, and PL quantum yield of SWCNT. An inverse linear relationship between the G-band normalized 267 cm(-1) RBM intensity and the PL emission intensities for SWCNT dispersions with different degrees of exfoliation was experimentally observed, indicating this can be used for quantitative characterization of the degree of exfoliation for a given SWCNT sample. An in-depth analysis of the indicators of the degree of exfoliation in various as-sonicated SWCNT dispersions highlights a two-stage exfoliation mechanism of SWCNT bundles under sonication. (c) 2009 Elsevier Ltd. All rights reserved.