Energy distribution in selected fragment vibrations in dissociation processes in polyatomic molecules. [HCN, DCN]

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

OSTI ID:7094049

Band, Y B; Freed, K F

The full quantum theory of dissociation processes in polyatomic molecules is converted to a form enabling the isolation of a selected fragment vibration. This form enables the easy evaluation of the probability distribution for energy partitioning between this vibration and all other degrees of freedom that results from the sudden Franck--Condon rearrangement process. The resultant Franck--Condon factors involve the square of the one-dimensional overlap integral between effective oscillator wavefunctions and the wavefunctions for the selected fragment vibration, a form that resembles the simple golden rule model for polyatomic dissociation and reaction processes. The full quantum theory can, therefore, be viewed as providing both a rigorous justification for certain generic aspects of the simple golden rule model as well as providing a number of important generalizations thereof. Some of these involve dealing with initial bound state vibrational excitation, explicit molecule, fragment and energy dependence of the effective oscillator, and the incorporation of all isotopic dependence. In certain limiting situations the full quantum theory yields simple, readily usable analytic expressions for the frequency and equilibrium position of the effective oscillator. Specific applications are presented for the direct photodissociation of HCN, DCN, and CO/sub 2/ where comparisons between the full theory and the simple golden rule are presented. We also discuss the generalizations of the previous theory to enable the incorporation of effects of distortion in the normal modes as a function of the reaction coordinate on the repulsive potential energy surface.

• Research Organization: Argonne National Laboratory, Argonne, Illinois 60439
• OSTI ID: 7094049
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 67:4; 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
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CYANIDES
DEUTERIUM COMPOUNDS
DISSOCIATION
ENERGY LEVELS
ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MOLECULES
OXIDES
OXYGEN COMPOUNDS
POLYATOMIC MOLECULES
SPECTRA
VIBRATIONAL STATES