Absorption spectra of 2 μg/mL SWCNT dispersion in NMP after 20 minutes of sonication (solid curve) and after subsequent centrifugation (dashed curve) and recentrifugation with the same parameters (dashed-dotted curve). The following values of were measured after sonication and first and second centrifugation, respectively: = 0.132 a.u., = 0.124 a.u., and = 0.115 a.u.