Direct study of the reactions of CH/sub 2/(X(tilde) /sup 3/B/sub 1/) radicals with H and D atoms

Journal Article · Thu Feb 26 04:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100289a034· OSTI ID:6358291

Boehland, T; Temps, F; Wagner, H Gg

The following reactions of CH/sub 2/ radicals in their triplet electronic ground state X(tilde) /sup 3/B/sub 1/ with hydrogen and deuterium atoms were investigated at room temperature and pressures of a few mbar in an isothermal discharge flow reactor: CH/sub 2/(X(tilde) /sup 3/B/sub 1/) + H(/sup 2/S) ..-->.. CH(/sup 2/II) + H/sup 2/(/sup 1/..sigma..) (1a) ..-->.. CH/sub 3/(/sup 2/A/sub 2/'') (1b); CH/sub 2/(X(tilde) /sup 3/B/sub 1/) + D(/sup 2/S) ..-->.. CH(/sup 2/II) + HD(/sup 1/..sigma..) (2a), ..-->.. CD(/sup 2/II) + H/sub 2/(/sup 1/..sigma..) (2b), ..-->.. CHD(/sup 3/B/sub 1/) + H(/sup 2/S) (2c), ..-->.. CH/sub 2/D(/sup 2/A/sub 2/'') (2d). CH/sub 2/ and CH radicals were detected with a far-infrared laser magnetic resonance (LMR) spectrometer while H and D atoms were monitored via their Lyman-..cap alpha.. vacuum ultraviolet resonance absorption. Direct measurements of the pseudo-first-order decay of (CH/sub 2/) in the presence of an excess of H or D yielded the rate constants k/sub 1/(298 K) = (1.1 +/- 0.3) x 10/sup 14/ cm/sup 3//(mol s) and k/sub 2/(298 K) = (1.1 +/- 0.3) x 10/sup 14/ cm/sup 3//(mol s). Under the conditions used the recombination channels 1b and 2d are negligible. Thus, the measured values correspond to k/sub 1/ = k/sub 1a/ and k/sub 2/ = K/sub 2a/ = k/sub 2b/ = k/sub 2c/. When the value for k/sub 1a/ is combined with literature data for the reverse reaction CH + H/sub 2/ ..-->.. CH/sub 2/ + H (-1a), the heat of formation of CH/sub 2/ radicals was found to be ..delta..H/sub f//sup 0/ /sub 298/(CH/sub 2/(X(tilde)/sup 3/B/sub 1/)) = 389 +/- 4 kJ/mol.

• Research Organization: Max-Planck-Institut fuer Stroemungsforschung, Goettingen, West Germany
• OSTI ID: 6358291
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:5; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ABSORPTION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DEUTERIUM
ELEMENTS
ENERGY LEVELS
ENTHALPY
EXPERIMENTAL DATA
FORMATION HEAT
GROUND STATES
HYDROGEN
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
KINETICS
LASERS
LIGHT NUCLEI
MAGNETIC RESONANCE
MEDIUM PRESSURE
MEDIUM TEMPERATURE
METHYLENE RADICALS
MULTIPLETS
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
PHYSICAL PROPERTIES
RADICALS
REACTION HEAT
REACTION KINETICS
RESONANCE
RESONANCE ABSORPTION
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
TRIPLETS