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.