Kinetics and product study of the reaction of CH{sub 3} radicals with O({sup 3}P) atoms using time resolved time-of-flight spectrometry

Journal Article · Thu Jul 22 04:00:00 EDT 1999 · Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory

DOI:https://doi.org/10.1021/jp991157k· OSTI ID:682154

Fockenberg, C; Hall, G E; Preses, J M; Sears, T J; Muckerman, J T ^[1]

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1. Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.

The combustion of methane is of considerable importance in the generation of energy. The kinetics and product distribution for the reaction of methyl radicals, CH{sub 3}, with ground-state O({sup 3}P) oxygen atoms have been investigated. This reaction was studied with a newly constructed apparatus combining a tubular flow reactor and a time-of-flight mass spectrometer (TOFMS), using a hollow-cathode lamp for photoionization. The radicals are produced by an excimer laser pulse ({lambda} = 193 nm) in the cophotolysis of acetone, CH{sub 3}COCH{sub 3}, or bromomethane, CH{sub 3}Br, and sulfur dioxide, SO{sub 2}, creating a homogeneous distribution of radicals along the axis of the flow reactor. A small fraction of the reaction mixture is sampled through a pinhole in the wall. Subsequent ionization and repeated extraction of ionized molecules into the TOFMS at a high repetition rate ({approx}20 kHz) allows the simultaneous observation of rapid changes in the concentration of multiple species in the flow reactor. In addition to the dominant product, formaldehyde (CH{sub 2}O), carbon monoxide (CO) was detected as a product with a yield of 0.17 {+-} 0.11. Analysis of the rate of disappearance of methyl radicals and appearance of formaldehyde for different O({sup 3}P) concentrations resulted in an overall rate coefficient for this reaction {kappa} = (1.7 {+-} 0.3) {times} 10{sup {minus}10} cm{sup 3}/molecule S at T = (299 {+-} 2) K and P = 1 Torr (He).

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 682154
• Journal Information: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 29 Vol. 103; ISSN 1089-5639; ISSN JPCAFH
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
CARBON MONOXIDE
COMBUSTION KINETICS
EXPERIMENTAL DATA
FORMALDEHYDE
METHANE
METHYL RADICALS
PHOTOLYSIS