Development of the Cn Ser signal with time

According to the theory of Raman enhancement by small metal particles, the Raman intensity of the CN" stretch vibration is determined by the size und number of particles (nuclei) and by the surface coverage by CN" ions on these particles. The results observed by SERS as depicted in Fig. 2 reflect the development of the crystalline structure of the silver layer on the metal surface: the adsorption of CN" ions is approximately constant for a given area. The change in the SER intensity could be explained by a change in the true area of the surface. Taking the double-layer capacity as a scale for the true area, the results shown in Figs. 3 and 4 admit the conclusion that the development of the signal intensity mainly depends on the development of the surface area during the deposition [1, 8]. Otherwise, the Raman enhancement is connected with a special microstrucure of the surface. One can conclude from the results of Fig. 3 that this microstructure must be established before the growth process starts. The result of Fig. 4 is that the development of the microstructure and the increase of the „true" surface area might not be simultaneous in this experiment. Both examples are shown in order to demonstrate the complex nature of electrocrystallization.

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