5 orders of magnitude (samples annealed in hydrogen at 150°C, 250°C, and

300°C), as is illustrated in Figure 6. The spacer influence on the SERS intensity is illustrated in Figure 7. To compare the spacer effect on the SERS signal obtained using differing MIFs, we performed similar measurements using a denser MIF (sample annealed in hydrogen at 300°C). The results of these measurements are presented in Figure 8. Comparing Figures 7 and 8, one can see that the influence of the spacer thickness is GDC-0449 clinical trial weaker in the case of a denser MIF, that is, the SERS signals go down slower. Figure 6 SERS spectra of rhodamine 6G. Rhodamine 6G was deposited onto uncoated (a) and coated with 3-nm TiO2 (b) films prepared using annealing in hydrogen at 150°C, 250°C, and 300°C. Measurement power 50 μW, spot diameter 5 μm, and exposure time 10 s. Insets: raw signal with background fluorescence. Figure 7 SERS spectra of rhodamine 6G. Measured using the TiO2-covered sample prepared using annealing in hydrogen at 250°C for different spacer thicknesses. Measurement power 50 μW, exposure time 20 s, and approximate spot size 5 μm. Inset: absorption spectrum of the initial MIF. Figure 8 SERS spectra of rhodamine 6G. Measured using the TiO2-covered sample prepared using annealing in hydrogen at 300°C for different spacer thicknesses. Measurement power 50 μW, exposure time 20 s, and approximate

spot size 5 μm. Inset: absorption spectrum of the initial MIF. Discussion The MIF formation occurs because the glass surface is a stronger sink for neutral silver IWP-2 mw atoms than the arising nuclei of metal silver in the bulk of the glass [25]. Thus, lowering the temperature and shortening the duration of hydrogen processing can provide prevailing of the MIF over the find more nanoparticles in the bulk of the glass growth. Varying

the hydrogen annealing temperature and duration allowed us to grow MIFs differing in silver nanoisland size and concentration. It is worth to note that longer SOD duration results in simultaneous increase of concentration and size of silver nanoislands. The position of SPR in the SOD-made MIFs falls in the spectral range below 500 nm, the exact position of the SPR being dependent Astemizole on the mode of the MIF preparation. These MIFs demonstrate their applicability in SERS and being covered with up to 7.5-nm-thick titania layers allow registering below a monolayer of rhodamine 6G. After ALD of titania, the shift of the SPR occurs in the TiO2-covered MIFs. This is due to the change in the dielectric surrounding of silver nanoislands. In our case, their shape is very close to a hemispherical one [17] and the shift occurs in the same way as in the case of spherical nanoparticles [26]. The origin of this shift is the loading of the electron-electric field oscillating system with a higher permittivity dielectric.