More pronounced differences were observed between TPP and Au/TPP absorption spectra. An apparent amplification of Soret band magnitude was observed on the Au/TPP structure in comparison with mere TPP layer. This phenomenon cannot be explained by only addition
Rucaparib manufacturer of Au and TPP layer absorption. Figure 5 Absorption (A) and luminescence (B) spectra of Au/TPP films on glass before and after annealing (T). Because the maximum of absorption peak lies at 440 nm, this wavelength was chosen for luminescence excitation. Figure 5B shows the porphyrin luminescence spectra of TPP and Au/TPP before and after annealing. Two luminescence maxima are seen at 660 and 730 nm. These maxima arise from singlet-singlet electron radiative transition and correspond to TPP’s two vibration states. After annealing, the luminescence of the TPP layer decreases slightly. The luminescence intensity of Au/TPP is higher than that of mere TPP layer. After annealing, the difference between TPP and Au/TPP luminescence spectra becomes more pronounced (the intensity increases twice). Sandwich film Sandwich structures were
prepared by gradual deposition of Au, TPP, and Au. After preparation, see more these structures were also annealed to achieve Au clustering. The surface morphology of these structures before and after annealing was determined by optical microscopy and AFM, and the typical images are shown in Figure 6. One can see that annealing leads to sufficient changes in the surface morphology. The supposed diffusion of gold atoms leads to disintegration of the initial multilayer structure. Figure 6 Optical and confocal images of Au/TPP/Au films deposited on glass before (A, B) and after annealing for 24 h (C, D). The typical AFM images of Au/TPP/Au multifilms GBA3 taken before and after annealing are shown in Figure 7. A nanostructured, random-ordered surface is well visible in Figure 7B. So, AFM measurement confirms changes in the surface morphology which are also seen from an increase of the surface roughness R a from 4.6 to 9.8 nm. For better characterization of surface morphology, a quantitative
analysis of AFM scans was also performed. Results are given in Table 1. Additional analyses of Au/TPP/Au structures by the SEM technique were also performed before and after annealing (Figure 4C,D). SEM images confirm AFM results, namely the increase of film roughness after annealing and the smoother surface of the Au/TPP/Au structure in comparison with the Au/TPP one. Additionally, the cross section of sandwich films was measured by the FIB-SEM technique (Figure 8). In this case, however, it is slightly difficult to identify the sandwich structure of the sample unambiguously. Figure 7 AFM of Au/TPP/Au and TPP films deposited on glass. Before (A) and after annealing (T) at 160°C for 24 h (B). Figure 8 FIB-SEM image of the cross section of the Au/TPP/Au/glass structure taken under an angle of 54.8°.