Resonance Raman spectra of copper-porphin

Abstract

Resonance Raman spectra of copper-porphin in solution have been obtained using the tunable rhodamine 6G dye, Ar+, and HeCd lasers for excitation. Several bands show variation of intensity with excitation wavelength and many combination and overtone bands have been observed with 5145 Å excitation. Depolarization ratios for the two anomalously polarized bands [ρl > (3/4)] at 1322 and 1587 cm−1 remain constant (∼45) with all the exciting wavelengths in the α and β absorption regions while some polarized bands show variation of their ρl values. It is shown that the rigorous molecular symmetry of Cu-porphin in solution is D4h. Symmetry species of the vibrational modes have been assigned.