Because additives, such as BME, are known to quench the triplet states of organic dyes, another mechanism that could account for the enhancement is a decreased intersystem crossing to SWNT triplet states. For example, the population of triplet states is often associated with fluorescence blinking of organic molecules, and passivation of trap states by addition of reducing agents has been demonstrated to suppress the blinking effect in single CdSe nanocrystals(23) and single dye molecules.(30) In both cases, the occurrence of blinking “off” periods was greatly diminished, and the QY of the blinking “on” periods stayed almost the same; however, the behavior observed here for SWNTs is strikingly different because these particles exhibited no blinking behavior, either before or after addition of reductants.