Reaction rate determinations of vinyl radical reactions with vinyl, methyl, and hydrogen atoms

Journal Article · Thu Apr 18 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100161a047· OSTI ID:5757020

Fahr, A; Laufer, A; Klein, R; Braun, W ^[1]

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1. National Inst. of Standards and Tech., Gaithersburg, MD (United States)

Laser photolysis-kinetic spectroscopy, end-product analysis, and detailed modeling were used to investigate three reaction systems in detail. Included were vinyl-vinyl, vinyl-methyl, and vinyl-methyl-hydrogen atoms. Product ratios, as a function of the rate constants could be approximated by using simple expressions. This greatly simplified the precise numerical modeling of these complex systems and also permitted a realistic error analysis. Reactions and rate constants (obtained at 25C, 100 Torr of He) in units of cm{sup 3} (molecule s){sup {minus}1} are summarized as follows: CH{sub 3} + CH{sub 3} {yields} C{sub 2}H{sub 6}, (0.52 {plus minus} 0.05) {times} 10{sup {minus}10}; C{sub 2}H{sub 3} + C{sub 2}H{sub 3} {yields} C{sub 4}H{sub 6}, (1.2 {plus minus} 0.2) {times} 10{sup {minus}10}; C{sub 2}H{sub 3} + C{sub 2}H{sub 3} {yields} C{sub 2}H{sub 2} + C{sub 2}H{sub 4}, (0.24 {plus minus} 0.05) {times} 10{sup {minus}10}; CH{sub 3} + C{sub 2}H{sub 3} {yields} C{sub 3}H{sub 6}, (1.2 {plus minus} 0.3) {times} 10{sup {minus}10}; CH{sub 3} + C{sub 2}H{sub 3} {yields} CH{sub 4} + C{sub 2}H{sub 2}, (0.34 {plus minus} 0.07) {times} 10{sup {minus}10}; C{sub 2}H{sub 3} + H {yields} C{sub 2}H{sub 4}, (2.0 {plus minus} 0.8) {times} 10{sup {minus}10}. The cross-combination rate constant obtained for vinyl-methyl is not twice the geometric mean of the vinyl-vinyl and methyl-methyl rate constants. This observation is explained on the basis that the vinyl-vinyl rate constant is faster than predicted by simple correlation arguments. The effect of bound low-lying triplet states of the product on the vinyl combination kinetics is discussed.

• OSTI ID: 5757020
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:8; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ABSORPTION SPECTROSCOPY
ALKYL RADICALS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
EXPERIMENTAL DATA
HYDROGEN
INFORMATION
KINETICS
LASER RADIATION
MATHEMATICAL MODELS
METHYL RADICALS
NONMETALS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
QUALITATIVE CHEMICAL ANALYSIS
RADIATIONS
RADICALS
REACTION KINETICS
SPECTROSCOPY
THEORETICAL DATA
THERMODYNAMICS
VINYL RADICALS