Interference effects on the H(2p) to H(2s) branching ratio in the photodissociation of hydrogen and deuterium

Journal Article · Wed Apr 15 04:00:00 EDT 1987 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.35.3339· OSTI ID:6011539

Beswick, J A; Glass-Maujean, M

Photodissociation cross sections for both H/sub 2/ and D/sub 2/ above the H(n = 1)+H(n = 2) threshold are presented. The partial cross sections into H(1s)+H(2s) and H(1s)+H(2p), obtained by full numerical integration of coupled Schroedinger equations, show pronounced oscillations as a function of the excitation energy. These oscillations are the result of a quantum interference effect between two dissociation paths leading to the same final state. The condition for this interference to occur is the existence in the Franck-Condon region of two dissociative states (B and B' in the case considered in this work) which can be excited at the same energy and which are coupled to each other by some nonadiabatic or other electronic interactions. The relationship between the full numerical calculation and the ''half-collision'' approximation is analyzed in detail. In addition, the predissociation of the D state, which occurs in the same spectral region, has also been studied. The line shapes obtained by solving the appropriate coupled Schroedinger equations are compared with those calculated by the use of perturbation theory. It is shown that, in order to have good agreement with the exact results, it is important to take into account contributions which are usually neglected, namely the contributions from the discrete spectrum of the final dissociative channel. Finally, the branching ratio ..cap omega.. = sigma(H/sub 2/..-->..H(1s)+H(2)sigma(H/sub 2/p..-->..H(1s)+H(2s) in the case of predissociation has been calculated and compared with other published calculations.

• Research Organization: Laboratoire pour l'Utilisation du Rayonnement Electromagnetique, Universite de Paris-Sud, Orsay 91405, France
• OSTI ID: 6011539
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 35:8; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
BRANCHING RATIO
COLLISIONS
CROSS SECTIONS
DEUTERIUM
DISSOCIATION
ELEMENTS
ENERGY DEPENDENCE
ENERGY LEVELS
EXCITED STATES
HYDROGEN
HYDROGEN ISOTOPES
INTERFERENCE
ISOTOPES
LIGHT NUCLEI
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OSCILLATIONS
PHOTON COLLISIONS
PHOTON-MOLECULE COLLISIONS
STABLE ISOTOPES