Semiclassical approach to spontaneous emission of molecular collision systems: A dynamical theory of fluorescence line shapes

Journal Article · Thu Apr 01 04:00:00 EST 1982 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.443464· OSTI ID:5651475

Lam, K; George, T F

A dynamical theory of spontaneous emission of molecular collision systems is presented. The theory makes use of specific nuclear trajectories in the time-dependent Schroedinger equation, and hence can be described as semiclassical. Transitions between electronic states are considered. The description of the radiative interaction is effected by photon-dressed electronic states (electronic-field representation) in both the diabatic and adiabatic representations with respect to the field interaction Hamiltonian. In the diabatic representation, one has to deal with two coupled differential--integral equations (Eqs.(21)), whereas in the adiabatic representation, only one (Eq.(75)) is required. The solutions to these equations are sought for using perturbative--interative procedures. It is then found that the diabatic representation, coupled with the stationary-phase approximation, allows an intuitive and pictorial interpretation of the nuclear dynamics involved, but is incapable of providing a tractable computational scheme valid for all frequency regimes. Indeed the stationary-phase approximation is in general only suitable for line-wing regions. The adiabatic representation, on the other hand, yields a unified line-shape expression. The nuclear dynamics in this representation, however, involves motion on complex and nonlocal potentials. An attempt has been made to reconcile this complicated dynamics with the more intuitive approach of a product of Landau-Zener transition probabilities, and also the generalization (to the case involving a quasicontinuum of avoided crossings) of the Miller-George technique of the analytic continuation of classical mechanics.

• Research Organization: Department of Chemistry, University of Rochester, Rochester, New York 14627
• OSTI ID: 5651475
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 76:7; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
FLUORESCENCE
LINE WIDTHS
LUMINESCENCE
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
SEMICLASSICAL APPROXIMATION
SPECTRA