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Author(s):   Christensen, L.E.; Okumura, M.; Sander, S.P.; Friedl, R.R.; Miller, C.E.; Sloan, J.J.
Title:   Measurements of the rate constant of HO2+NO2+N2->HO2NO2+N2 using near-infrared wavelength-modulation spectroscopy and UV-visible absorption spectroscopy
Journal:   J. Phys. Chem. A
Volume:   108
Page(s):   80 - 91
Year:   2004
Reference type:   Journal article
Squib:   2004CHR/OKU80-91

Reaction:   N2O4NO2 + NO2
Reaction order:   1
Temperature:   231 K
Pressure:  0.13 bar
Rate expression:   3.6x101 [±1.0x101 s-1]
Bath gas:   N2
Category:  Experiment
Data type:   Derived from detailed balance/reverse rate
Pressure dependence:   None reported
Experimental procedure:   Static or low flow - Data taken vs time
Excitation technique:   Flash photolysis (laser or conventional)
Time resolution:   In real time
Analytical technique:   Vis-UV absorption
Comments:   Measured rate constants for HO2 + NO2 -> HO2NO2. Corrected observed rate constants for secondary reactions. From pressure dependence and assuming fall off parameter Fc=0.6 derived high pressure and low pressure limiting rate expressions. HO2 is produced following 308 nm photolysis of Cl2 via the reactions CH3OH + Cl -> CH2OH + HCl and then CH2OH + O2 -> CH2O + HO2. HO2 is detected in the near-IR at 6638.2 cm-1 usinhg heterodyne absorption with a diode laser. NO2 monitored using UV-visible absorption. In this work it was determined that side reaction NO2 + NO2 <-> appears to influence NO2 under these conditions, and may have impacted the accuracy of prior measurements of the HO2 + NO2 rate constants.

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