Theory of resonant Raman scattering in the strong vibronic coupling limit--a Green's function approach

Journal Article · Fri Jul 15 04:00:00 EDT 1977 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.434842· OSTI ID:7219645

Hong, H

A Green's function approach for resonant Raman scattering is proposed here, which is suitable for both weak and strong vibronic couplings. The formalism is based on the solution of the exact Green's function in the Longuet--Higgins representation, using the solutions to the static equations in ordinary molecular quantum mechanics as the basis set. The physical meaning of various interaction schemes becomes clear in this representation. In particular, the vibronic coupling is based on the interactions between individual zero-order vibronic levels and is carried through to infinite order, whereas the traditional first-order results only account for the emission of one single vibrational quantum. Nonadiabatic contributions are also contained in the formulation. The method is applied to the following cases: (1) the change in nuclear equilibrium position due to electronic excitation, (2) vibronic coupling involving two excited states, and (3) the change in nuclear potential (force constants) due to electronic excitation. Numerical results show that the convergence is excellent even for large vibronic coupling and in exact resonance region. Furthermore, all the physical quantities of interest, such as Raman cross sections of fundamentals and overtones, absorption profiles, Franck--Condon factors, quantum yields can be obtained at the same time in this unified approach.

• Research Organization: Department of Chemistry and Radiation Laboratory University of Notre Dame, Notre Dame, Indiana 46556
• OSTI ID: 7219645
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 67:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640305* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Theory-- (-1987)
74 ATOMIC AND MOLECULAR PHYSICS
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
GREEN FUNCTION
LIGHT SCATTERING
RAMAN EFFECT
VIBRATIONAL STATES