Visualization of deep ultraviolet photons based on Förster resonance energy transfer and cascade photon reabsorption in diphenylalanine-carbon nitrides composite film

Abstract

A diphenylalanine (L-Phe-L-Phe, FF)-carbon nitride composite film is designed and fabricated to visualize the deep ultraviolet (DUV, 245–290 nm) photons. The FF film, composed of diphenylalanine molecules, doped with carbon nitrides shows blue emission under excitation of DUV light, which makes the DUV beam observable. Both Förster resonance energy transfer and cascade photon reabsorption contribute to the conversion of photon energy. First, the FF is excited by the DUV photons. On one hand, the energy transfers to the embedded carbon nitrides through nonradiative dipole–dipole couplings. On the other hand, the 284 nm photons emitted from the FF would further excite the carbon nitrides, which will finally convert to blue fluorescence. Herein, the experimental demonstration of a simple device for the visualization of high DUV fluxes is reported.