Size-Dependent One- and Two-Photon Fluorescence of Acetonitrile-Derived Carbon Dots

Carbon dots – carbonaceous luminescent nanoparticles – are increasingly employed in bioimaging, fluorescent sensing, photocatalysis, and light emitting devices. The nanoparticle size is the key morphological parameter, affecting optical properties of carbon dots. To study the relation between the size and linear and nonlinear light absorption and luminescence of carbon dots, we separated products obtained by laser synthesis from acetonitrile into fractions of different size and analyzed their optical properties and chemical composition. We found that the nanoparticle diameter influences photoluminescence spectra, lifetimes and quantum yields. A size-dependent difference in fluorescence excited by one- and two-photon absorption was also revealed.