Knowledge Bank

The SERS spectra of tetrapheylporphine(TPP) and iron ($\Pi$) protoporphyrin IX $(Fe(\Pi )PP)$ were obtained. Comparing of these two spectra, the bands 994, 1126, 1174, $1218cm-1$ in spectra of TPP assigned to $v(C\ast -Cm),v(C\ast -N)$ were disappeared or the bands intensity decreased in SERS spectra of $Fe(\Pi )PP$. The band $1480cm-1$ assigned to $v(C\ast =-C\ast )$ in spectra of TPP was also disappeared in spectra of $Fe(\Pi )PP$. In the region of $1500-1700cm-1$, there were three bands 1544, 1584, $1514cm-1$ for TPP and two bands 1578, $1632cm-1$ for $Fe(\Pi )PP$. Moreover, the band $1578cm-1$ was enhanced intensity comparing with $1632cm-1$ in SERS spectra of $Fe(\Pi )PP$. All these information indicated that, the porphyrin ring of TPP adsorbed on the surface of silver colloid by the four N atoms. But, for the $Fe(\Pi )PP$, since the four N atoms have complexed with $Fe(\Pi )PP$, the vibration modes of $v(C\ast -Cm),v(C\ast -N)$ were disappared.