Photoluminescence Brightening of Isolated Single-Walled Carbon Nanotubes

The addition of dithiothreitol (DTT) to a suspension consisting of either DNA- or sodium-dodecyl-sulfate (SDS)-wrapped single-walled carbon nanotubes (SWCNTs) caused significant photoluminescence (PL) brightening from the SWCNTs, whereas PL quenching to different extents was observed for other surfactant–SWCNT suspensions. PL lifetime studies with high temporal resolution show that the addition of DTT mitigates nonradiative decay processes but also surprisingly increases the radiative decay rate for DNA– and SDS–SWCNTs. Completely opposite effects on the decay rates are found for the other surfactant–SWCNTs that show PL quenching. We propose that the PL brightening results from a surfactant reorganization upon DTT addition.