J. Eur. Opt. Society-Rapid Publ. 22, 28( 2026) 287
Fig
. 2. Fluorescence intensity spectra of a) CV, b) NR and c) RB on nanostructured Al films; dashed black: reference, green / blue / red: 2 / 4 / 6 nm Al. Inset are the MEF with logarithmic y scale.
Fig
. 3. SEM micrographs showing the morphology obtained following the deposition of Ag layers structured by annealing:( a) 15 nm,( b) 20 nm,( c) 25 nm.
Fig
. 4. Fluorescence intensity spectra of a) CV, b) NR and c) RB on nanostructured Ag films; dashed black: reference, green / blue / red: 15 / 20 / 25 nm Ag. Inset are the MEF with logarithmic y scale.
the transition from isolated nanoparticle regimes toward a densely packed morphology, which is consistent with enhanced surface diffusion, particle aggregation, and lateral growth during thermal treatment.
Figure 4 presents the fluorescence emission spectra of CV, NR, and RB fluorophores films deposited on thermally annealed Ag nanostructures, in comparison with a reference substrate, with an inset graph on a logarithmic scale. The fluorescence measurements reveal substantial intensity increases relative to the reference for all fluorophores, with
EF dependent on Ag thickness and fluorophore: for CV the EF increases from 6.8( 15 nm) to 10( 20 nm) and 19( 25 nm), for NR from 2.4( 15 nm) to 4( 20nm) and 4.4( 25 nm), and for RB from 2( 15 nm) to 4( 20 nm) and 6( 25nm).
Table 2 summarizes the fluorescence EF for CV, NR, and RB deposited on nanostructured Al and Ag films of varying thicknesses. For Al substrates, moderate enhancement is observed, with EF values increasing with thickness for CV and RB and showing an optimum at 4 nm for NR.