The advancement of carbon nanomaterials has made this extensively exploited chemical element ubiquitous in nanoscience exploration. Carbon dots are novel carbon nanomaterials capable of wavelength-tunable emission with nanoscale photophysical performance without a size dependence. Fluorescence intermittency or blinking in carbon dots has been attributed to energy transfer between defects on the surface. Current theories of carbon dot emission involve a mechanism for these blinking events based on competing nonradiative pathways. However, there has been no determination if the number of emitters on a single carbon dot exceeds one, nor how multiple emitters might contribute to blinking. Through simultaneous single-molecule spectroscopy and emission anisotropy measurements, we identified multiple emitters from single carbon dots based on changes in emission polarization after individual carbon dot blinking events. The simultaneous spectral acquisition provides spectroscopic signatures that show additional evidence of multiple emitters through spectral shifts following blinking events. Through this unique multidimensional single-molecule technique, we conclude that that there is support for at least two distinct defects contributing to the emission of carbon dots.

Identifying multiple emitters in carbon dots

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