Raman Excitation Profiles of Copper Tetraphenylporphyrin in a Nitrogen Matrix.

The Raman Excitation Profiles of copper tetraphenylporphyrin in a nitrogen matrix were constructed from 152 Raman spectra collected throughout the Q band region. Absorption spectra of CuTPP in six environments were also collected to assess their effects on the molecule. A Born-Huang non-adiabatic perturbation theory is derived for porphyrins which can explain the strong coupling behavior exhibited by this data. It is found that the third order terms in the Raman scattering tensor are responsible for the strong coupling effects. This occurs not because the third order terms are abnormally large, but because the first and second order Q band scattering terms are very small for CuTPP.