Solids, exhibiting SERS

The SEES signals of 4-PYS are almost identical to the normal Raman spectrum of a solid 4-PYS. That is, the conformation of 4-PYS on the silver electrode is almost the same as that in the bulk. Since no SERS signals for cytochrome c are observed, as shown in Figure 6 (curve A), cytochrome c molecules are considered to be located at least more than 0.5 nm from the electrode surface. The adsorption of 4-PYS is so strong that cytochrome c pre adsorbed on the silver electrode may be completely displaced by 4-PYS and the adsorbed layer of 4-PYS is hardly displaced by cytochrome c (only small Raman peaks are observable when cytochrome c is present in the solution). This electrode exhibits a quasi-reversible voltammetric response at the potential corresponding to the formal potential of native cytochrome c. That is, cytochrome c remains immobilized on the 4-PYS modified electrode. The electron transfer reaction of... 

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