Composite Film Structures with Fluorophores and CdTe Quantum Dots for Selective Fluorescent Detection of Ammonia Molecules at Ultra-Low Concentrations

The work presents the results of the synthesis and investigation of the spectral-fluorescence characteristics of gas-sensing film composite structures based on ethylene vinyl acetate (EVA), microporous silicate sorbent SiO2, colloidal quantum dots of CdTe, and fluorescently active dyes of the coumarin group. An increase in the fluorescence intensity of the alcohol solution of the coumarin 7 dye is revealed upon the addition of a solution of colloidal CdTe quantum dots (λ = 530 nm) due to the F¨orster resonance energy transfer (FRET). It is experimentally established that the synthesized gas sensor structures had a fluorescent response to volatile ammonia molecules in a steam-gas sample in trace concentrations (0.5–10 ppm). Created gas sensor material demonstrates the ability to restore the initial sensor properties at the end of each measurement cycle. The proposed polymer structures have prospective in use as sensitive elements of fluorescent sensors of ammonia trace concentrations in air.