Collision-induced intramolecular energy transfer and dissociation of acetone molecular ion

Journal Article · Tue May 15 04:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458369· OSTI ID:6941394

Qian, K; Shukla, A; Futrell, J ^[1]

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1. Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 (USA)

Two crossed-beam instruments with different geometry and with low pressure and differentially pumped ion sources were used to investigate collision-induced dissociation (CID) of acetone molecular ions activated by He and Ar collisions over the kinetic energy range 0.45--10 eV (center of mass). Long-lived electronically excited state(s) which back-scatter superelastically with conversion of 2.2{plus minus}0.3 eV of internal energy into translational energy dominate the low collision energy ({ital E}{sub rel} {lt}2 eV) CID of the acetone ion. This energy release matches the {ital X}{l arrow}{ital A} electronic excitation energy difference, suggesting a very efficient {ital E}{r arrow}{ital T} energy transfer mechanism for this system. The location of the intensity maximum for this mechanism on the relative velocity vector (fully rebound peak) indicates that small impact parameter head-on'' collisions trigger this energy transfer process. A curve-crossing mechanism is suggested to rationalize these results. At collision energies of 6 eV and higher the superelastic scattering mechanism is no longer observed. Translationally endothermic forward (but nonzero angle) scattering takes over as the predominant CID mechanism. The dynamics are consistent with the hypothesis that the endothermic CID channel proceeds on the electronically excited surface and involves the efficient {ital T}{r arrow}{ital E} excitation of ground state acetone ions.

• OSTI ID: 6941394
• 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

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ACETONE
ARGON
ATOM COLLISIONS
ATOMIC BEAMS
BEAMS
CHARGED PARTICLES
COLLISIONS
DATA
DISSOCIATION
ELEMENTS
ENERGY RANGE
ENERGY TRANSFER
EV RANGE
EV RANGE 01-10
EXPERIMENTAL DATA
FLUIDS
GASES
HELIUM
INFORMATION
ION COLLISIONS
ION-ATOM COLLISIONS
IONS
KETONES
MOLECULAR BEAMS
MOLECULAR IONS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
RARE GASES