Enhancement of the Anti-Stokes Fluorescence of Hollow Spherical Carbon Nitride Nanostructures by High Intensity Green Laser

Fluorescence spectra of graphitic (g-C(3)N(4)) and spherical (s-C(3)N(4)) modifications of carbon nitride were measured as a function of green pulsed (6 ns-pulse) laser intensity. It was found that the intensity of the laser increases the maximum of the fluorescence shifts towards the anti-Stokes side of the fluorescence for s-C(3)N(4) spherical nanoparticles. This phenomenon was not observed for g-C(3)N(4) particles. The maximum of the anti-Stokes fluorescence in s-C(3)N(4) nanoparticles was observed at 480 nm. The ratio of the intensity of the anti-Stokes peak (centered at 480 nm) to that of the Stokes peak (centered at 582 nm) was measured to be I(484/582) = 6.4 × 10(−3) at a low level of intensity (5 mW) of a green pulsed laser, whereas it rose to I(484/582) = 2.27 with a high level of laser intensity (1500 mW).