Kinetics and mechanism of the photooxidation of formaldehyde. 2. Molecular modulation studies

Journal Article · Thu Mar 23 00:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100343a034· OSTI ID:5061450

Burrows, J P; Moortgat, G K; Tyndall, G S ^[1]; Cox, R A; Jenkin, M E; Hayman, G D ^[2]; Veyret, B ^[3]

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1. Max Planck Institut fuer Chemie, Mainz (Germany, F.R.)
2. Harwell Lab., Didcot, Oxfordshire (England)
3. Universite de Bordeaux l, Talence (France)

Transient species in the photooxidation of formaldehyde in air have been investigated by using the technique of modulated photolysis-long path kinetic spectroscopy. A transient absorption spectrum consisting of a broad band with a maximum near 230 nm was observed, which is attributed to the HOCH{sub 2}O{sub 2} radical formed by the reaction HO{sub 2} + HCHO {yields} HOCH{sub 2}O{sub 2} (1). The equilibrium constant, K{sub 1}*, was estimated from these measurements of the HOCH{sub 2}O{sub 2} radical together with measurements of HO{sub 2} obtained with diode laser infrared absorption spectroscopy: K{sub 1}* = 4.0 (+4.0, -2.0) {times} 10{sup {minus}16} cm{sup 3} molecule{sup {minus}1} at 298 K. Kinetic measurements of the two radicals allowed determination of the rate coefficients at 298 K for the following reactions: HOCH{sub 2}O{sub 2} + HO{sub 2} {yields} products (3), k{sub 3} = (1.2 {plus minus} 0.3) {times} 10{sup {minus}11} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}; 2HOCHO{sub 2}O{sub 2} {yields} HCOOH + CH{sub 2}(OH){sub 2} + O{sub 2} (4b), k{sub 4b} = (5.6 {plus minus} 2.8) {times} 10{sup {minus}13} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. The alternative pathway, 2HOCH{sub 2}O{sub 2} {yields} 2HOCH{sub 2}O + O{sub 2} (4a), followed by HOCH{sub 2}O + O{sub 2}, leads to the chain generation of formic acid. The rate coefficient for reaction 4a, k{sub 4a} = (5.5 {plus minus} 1.1) {times} 10{sup {minus}12} cm{sup 3} molecule{sup {minus}1} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}, was determined from the yields of formic acid.

• OSTI ID: 5061450
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:6; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
FORMALDEHYDE
OXIDATION
ABSORPTION SPECTROSCOPY
ATMOSPHERIC CHEMISTRY
BRANCHING RATIO
CHEMICAL REACTION KINETICS
CROSS SECTIONS
EQUILIBRIUM
EXPERIMENTAL DATA
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
ULTRAVIOLET SPECTRA
ALDEHYDES
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
INFORMATION
KINETICS
NUMERICAL DATA
ORGANIC COMPOUNDS
REACTION KINETICS
SPECTRA
SPECTROSCOPY
400500* - Photochemistry
540110