A spectrokinetic study of CH₂I and CH₂IO₂ radicals

TY - JOUR

T1 - A spectrokinetic study of CH2I and CH2IO2 radicals

AU - Sehested, Jens

AU - Ellermann, Thomas

AU - Nielsen, Ole John

PY - 1994/1/1

Y1 - 1994/1/1

N2 - The UV absorption spectrum and kinetics of CH2I and CH2IO2 radicals have been studied in the gasphase at 295 K using a pulse radiolysis UV absorption spectroscopic technique. UV absorption spectra of CH2I and CH2IO2 radicals were quantified in the range 220–400 nm. The spectrum of CH2I has absorption maxima at 280 nm and 337.5 nm. The absorption cross‐section for the CH2I radicals at 337.5 nm was (4.1 ± 0.9) × 10−18 cm2 molecule−1. The UV spectrum of CH2IO2 radicals is broad. The absorption cross‐section at 370 nm was (2.1 ± 0.5) × 10−18 cm2 molecule−1. The rate constant for the self reaction of CH2I radicals, k = 4 × 10−11 cm3 molecule−1 s−1 at 1000 mbar total pressure of SF6, was derived by kinetic modelling of experimental absorbance transients. The observed self‐reaction rate constant for CH2IO2 radicals was estimated also by modelling to k = 9 × 10−11 cm3 molecule−1 s−1. As part of this work a rate constant of (2.0 ± 0.3) × 10−10 cm3 molecule−1 s−1 was measured for the reaction of F atoms with CH3I. The branching ratios of this reaction for abstraction of an I atom and a H atom were determined to (64 ± 6)% and (36 ± 6)%, respectively. © 1994 John Wiley & Sons, Inc.

AB - The UV absorption spectrum and kinetics of CH2I and CH2IO2 radicals have been studied in the gasphase at 295 K using a pulse radiolysis UV absorption spectroscopic technique. UV absorption spectra of CH2I and CH2IO2 radicals were quantified in the range 220–400 nm. The spectrum of CH2I has absorption maxima at 280 nm and 337.5 nm. The absorption cross‐section for the CH2I radicals at 337.5 nm was (4.1 ± 0.9) × 10−18 cm2 molecule−1. The UV spectrum of CH2IO2 radicals is broad. The absorption cross‐section at 370 nm was (2.1 ± 0.5) × 10−18 cm2 molecule−1. The rate constant for the self reaction of CH2I radicals, k = 4 × 10−11 cm3 molecule−1 s−1 at 1000 mbar total pressure of SF6, was derived by kinetic modelling of experimental absorbance transients. The observed self‐reaction rate constant for CH2IO2 radicals was estimated also by modelling to k = 9 × 10−11 cm3 molecule−1 s−1. As part of this work a rate constant of (2.0 ± 0.3) × 10−10 cm3 molecule−1 s−1 was measured for the reaction of F atoms with CH3I. The branching ratios of this reaction for abstraction of an I atom and a H atom were determined to (64 ± 6)% and (36 ± 6)%, respectively. © 1994 John Wiley & Sons, Inc.

UR - http://www.scopus.com/inward/record.url?scp=0028379784&partnerID=8YFLogxK

U2 - 10.1002/kin.550260204

DO - 10.1002/kin.550260204

M3 - Journal article

AN - SCOPUS:0028379784

SN - 0538-8066

VL - 26

SP - 259

EP - 272

JO - International Journal of Chemical Kinetics

JF - International Journal of Chemical Kinetics

IS - 2

ER -