Rate constants for the reactions of CH/sub 3/ and CD/sub 3/ radicals with molecular oxygen
Photoionization mass-spectrometry was used to measure the rate constants for the gas phase reactions of methyl radicals, both CH/sub 3/ and CD/sub 3/, with molecular oxygen. The CH/sub 3/ + O/sub 2/ reaction was investigated at room temperature for total pressures ranging from 0.5 to 6 Torr in three different bath gases; argon, helium and nitrogen. Significant curvature was observed in the plot of experimental rate constants versus total pressure. The rate constants appeared to extrapolate to zero at zero pressure. Thus there is no evidence of a two-body reaction between oxygen molecules and methyl radicals. The CD/sub 3/ reaction was also studied at room temperature for total pressures between 1 and 6 Torr using argon as the bath gas. The rate constants for the CD/sub 3/ + O/sub 2/ reaction were determined to be about twice as fast as those for the CH/sub 3/ reaction. A full theoretical RRKM calculation has been carried out for both the CH/sub 3/ and CD/sub 3/ + O/sub 2/ reactions. The RRKM calculated value for the low pressure-limiting rate constants were 1.90 and 3.72 x 10/sup -31/ cm/sup 6//mole/sup 2/ sec for the CH/sub 3/ and CD/sub 3/ reactions, respectively. The RRKM calculated rate constants for the DC/sub 3/ + O/sub 2/ reaction were 1.96 times faster than those calculated for the CH/sub 3/ reaction, in good agreement with the experimentally determined ratio of about 2:1.
- Research Organization:
- California Univ., Los Angeles (USA)
- OSTI ID:
- 5838044
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKYL RADICALS
ARGON
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DEUTERATION
DEUTERIUM
ELEMENTS
EXPERIMENTAL DATA
FLUIDS
GASES
HELIUM
HYDROGEN ISOTOPES
INFORMATION
IONIZATION
ISOTOPE EFFECTS
ISOTOPE ENRICHED MATERIALS
ISOTOPES
KINETICS
LIGHT NUCLEI
LOW PRESSURE
MASS SPECTROSCOPY
MATERIALS
MEDIUM TEMPERATURE
MEDIUM VACUUM
METHYL RADICALS
NITROGEN
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
OXYGEN
PHOTOIONIZATION
RADICALS
RARE GASES
REACTION KINETICS
SPECTROSCOPY
STABLE ISOTOPES