Theory of resonant Raman scattering. III. Toward the total synthesis of molecular spectra and Raman excitation profiles within the generalized vibronic theory and from an excitoninmolecule viewpoint
Abstract
Applications of the Green's function method to the interpretation of molecular electronic spectra and Raman excitation spectra are further elaborated here. In particular, basic concepts in the generalized vibronic theory of Raman intensity are introduced, as well as the concept of vibrational lattices and the exciton analogy. It is pointed out that the Raman process can be considered from the solid state viewpoint as energy transfer (exciton migration) processes. Therefore, vibronic problems for a polyatomic molecule having M normal modes are analogous to an exciton in Mdimensional space. It is further shown that most problems in onedimensional space (one mode problems) can be exactly treated with the Green's function technique in the framework of the generalized vibronic theory. This allows us to handle specifically (1) FranckCondon effect with both changes in equilibrium positions and force constants upon electronic excitation, (2) nonadiabatic HerzbergTeller couplings with force constant changes in excited states, and (3) mixed harmonicquartic oscillators, etc. More complicated vibronic schemes can be dealt with in a similar fashion. For example, vibrational combinations and the Duschinsky effect in electronic and Raman spectroscopy can be treated as pseudoonedimensional problems. Green's functions for multiple mode problems with simple vibronic coupling schemes are given. Some approaches are also provided for the total synthesis of molecular spectra and Raman excitation spectra.
 Publication:

Journal of Chemical Physics
 Pub Date:
 February 1978
 DOI:
 10.1063/1.435847
 Bibcode:
 1978JChPh..68.1253H
 Keywords:

 Molecular Spectroscopy;
 Raman Spectra;
 Resonance Scattering;
 Spectrum Analysis;
 Absorption Spectra;
 Coupled Modes;
 Electronic Spectra;
 Excitons;
 FranckCondon Principle;
 Green'S Functions;
 Molecular Excitation;
 Vibration Mode;
 Vibrational Spectra;
 Atomic and Molecular Physics;
 33.20.Fb;
 33.70.Fd;
 Raman and Rayleigh spectra;
 Absolute and relative line and band intensities