State-to-state dynamics of atom + polyatom abstraction reactions. I. The H+CD sub 4 r arrow HD( v prime , J prime )+CD sub 3 reaction
- Department of Chemistry, University of California, Irvine, California 92717 (United States)
- Department of Chemistry, Columbia University, New York, New York 10027 (United States)
We report measurement of the HD product quantum state distributions and absolute cross section for the H+CD{sub 4}{r arrow}HD({ital v}{prime},{ital J}{prime})+CD{sub 3} reaction at a collision energy of 1.5 eV. The total reaction cross section is small, 0.14{plus minus}0.03 A{sup 2}, making the experimental measurements difficult. The HD quantum state distribution peaks at low {ital J}{prime} in both {ital v}{prime}=0 and {ital v}{prime}=1, the only vibrational states in which product is observed. Very little of the 1.5 eV available energy appears as internal excitation of the HD product molecule, 7% in HD product vibration and 9% in rotation. However, linear surprisal analysis shows that this limited internal energy disposal in the HD product in some ways exceeds that expected statistically, since two of the best-fit surprisal parameters ({Theta}{sub {ital r}}=2.9{plus minus}0.6 for {ital v}{prime}=0, {Theta}{sub {ital r}}={minus}1.9{plus minus}0.5 for {ital v}{prime}=1, {lambda}{sub {ital v}}={minus}2.2{plus minus}0.6 ) are negative. The HD rovibrational state distribution shows an anomalous positive correlation of product vibrational and rotational excitation. Those molecules formed in the vibrationally excited state, {ital v}{prime}=1, have significantly more rotational energy ({l angle}{ital E}{sub rot}{r angle}=0.17 eV) than those molecules formed in the vibrational ground state, {ital v}{prime}=0 ({l angle}{ital E}{sub rot}{r angle}=0.13 eV). This behavior runs counter to the otherwise universal behavior for direct bimolecular reactions---a negative correlation of product vibrational and rotational excitation. We speculate as to the source of this anomalous energy disposal.
- OSTI ID:
- 5128428
- Journal Information:
- Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 96:3; ISSN JCPSA; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ALKANES
ATOMS
CHEMICAL REACTIONS
CROSS SECTIONS
DEUTERATION
DEUTERIDES
DEUTERIUM COMPOUNDS
DISTRIBUTION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN DEUTERIDE
MECHANICS
METHANE
MOLECULES
NONMETALS
ORGANIC COMPOUNDS
POLYATOMIC MOLECULES
QUANTUM MECHANICS
ROTATIONAL STATES
TOTAL CROSS SECTIONS
VIBRATIONAL STATES