Vibrational assignment and definite harmonic force field for porphine .2. Comparison with nonresonance Raman data

The nonresonance Raman spectrum of free base porphine has been measured using near infrared excitation. The observed frequencies and intensities are compared with results from the scaled quantum mechanical (SQM) force field presented in part I. The SQM force field is based on density functional calculations, scaled to fundamentals taken from matrix infrared and luminescence spectra. The good agreement between the predicted and measured spectra enables us to assign conclusively the symmetries and vibrational forms in the observed Raman spectrum. The depolarization ratios of the a(g) fundamentals are discussed in terms of a simple preresonance model. The vibrational frequencies in the inactive out-of-plane a(u) symmetry species are predicted.