Photodissociation of CO sup minus sub 3 : Product kinetic energy measurements as a probe of excited state potential surfaces and dissociation dynamics

Journal Article · Tue May 15 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458363· OSTI ID:6807609

Snodgrass, J T; Roehl, C M; van Koppen, P A.M.; Palke, W E; Bowers, M T ^[1]

---

1. Department of Chemistry, University of California, Santa Barbara, California 93106 (USA)

The photodissociation process CO{sup {minus}}{sub 3} +{ital h}{nu}{r arrow}O{sup {minus}}+CO{sub 2} has been investigated at photon energies of 2.41, 2.50, 2.54, 2.60, and 2.71 eV. Experiments were conducted by crossing a mass-selected, 8 keV ion beam with a linearly polarized laser beam, and measuring the kinetic energy distributions of the charged photodissociation products. By varying the angle between the ion beam and laser polarization, angular distributions were obtained at photon energies of 2.41 and 2.54 eV. The photon energy dependence of the average photofragment kinetic energies shows conclusively that photodissociation at these photon energies does not proceed by a direct dissociation process on a repulsive potential surface, or by a statistical vibrational predissociation process on a bound surface. The photofragment angular distributions are isotropic, providing further evidence that precludes direct photodissociation on a repulsive potential surface. {ital Ab} {ital initio} calculations were performed using the GAUSSIAN86 programs. These calculations indicate that ground state CO{sup {minus}}{sub 3} has a planar {ital D}{sub 3}{sub {ital h}} geometry, and {sup 2}{ital A}{sup {prime}}{sub 2} electronic symmetry. This ground state correlates adiabatically to the CO{sup {minus}}{sub 2} +O dissociation asymptote, not the lower energy O{sup {minus}}+CO{sub 2} asymptote. Taken together, these new experimental and theoretical results suggest that the photodissociation of CO{sup {minus}}{sub 3} at these energies occurs via the interaction of bound and repulsive excited state potential surfaces. A new model of the potential surfaces of CO{sup {minus}}{sub 3} is proposed.

• OSTI ID: 6807609
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:10; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
640301* -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR DISTRIBUTION
ANIONS
BEAMS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COLLISIONS
DATA
DECOMPOSITION
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ENERGY
ENERGY RANGE
ENERGY SPECTRA
EXPERIMENTAL DATA
INFORMATION
ION BEAMS
ION COLLISIONS
IONS
KEV RANGE
KEV RANGE 01-10
KINETIC ENERGY
LASER RADIATION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
OXYGEN IONS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHOTON COLLISIONS
PHOTON-ION COLLISIONS
RADIATIONS
SPECTRA
YIELDS