Kinetics of reactions of CH sub 3 O sub 2 and HOCH sub 2 CH sub 2 O sub 2 radicals produced by the photolysis of iodomethane and 2-iodoethanol

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

DOI:https://doi.org/10.1021/j100161a049· OSTI ID:5756809

Jenkin, M E; Cox, R A ^[1]

---

1. Harwell Lab., Oxfordshire (United Kingdom)

The molecular modulation technique coupled with UV absorption spectroscopy has been used to investigate the UV spectra and kinetics of reactions of the methylperoxy radical (CH{sub 3}O{sub 2}) and the 2-hydroxyethylperoxy radical (HOCH{sub 2}CH{sub 2}O{sub 2}), generated by the 254-nm photolysis of the organic iodides CH{sub 3}I and HOCH{sub 2}CH{sub 2}I: RI + h{nu}({lambda}=254 nm) {yields} R + I and R + O{sub 2} + M {yields} RO{sub 2} + M. These are believed to be CH{sub 3}OOI and HOCH{sub 2}CH{sub 2}OOI formed as intermediates in the RO{sub 2}-chaperoned recombination of iodine atoms. Both CH{sub 3}O{sub 2} and HOCH{sub 2}CH{sub 2}O{sub 2} were found to obey second-order kinetic behavior owing to removal by a series of reactions initiated by the self-reactions: CH{sub 3}O{sub 2} + CH{sub 3}O{sub 2} {yields} products and HOCH{sub 2}CH{sub 2}O{sub 2} + HOCH{sub 2}CH{sub 2}O{sub 2} {yields} products. Additional measurements made over the temperature range 268-350 K indicated that this parameter displays a weak negative temperature dependence. E/R was found to have a value of {minus}220 {plus minus} 72 K at 760 Torr, and a value of {minus}92 {plus minus} 53 K at 10.8 Torr. The parameter k{sub 10obs}/{sigma} had a value of (6.8 {plus minus} 0.4) {times} 10{sup 5} cm s{sup {minus}1} at 230 nm (p = 760 Torr, T = 298 K). Assuming the photolysis of HOCH{sub 2}CH{sub 2}I leads exclusively to the production of HOCH{sub 2}CH{sub 2}O{sub 2}, the following values of {sigma}(230 nm) and k{sub 10obs} were concluded: {sigma}(230nm)= (2.35 {plus minus} 0.25) {times} 10{sup {minus}18} cm{sup 2} molecule{sup {minus}1} and k{sub 10obs} = (1.60 {plus minus} 0.17) {times} 10{sup {minus}12} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}.

• OSTI ID: 5756809
• 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
400500* -- Photochemistry
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
ABSORPTION SPECTROSCOPY
ALKYL RADICALS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EXPERIMENTAL DATA
INFORMATION
KINETICS
LOW PRESSURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PEROXY RADICALS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRESSURE DEPENDENCE
RADICALS
REACTION INTERMEDIATES
REACTION KINETICS
SPECTRA
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TIME DEPENDENCE
ULTRAVIOLET SPECTRA