Absorption Spectrum and Reaction Kinetics of the HO2 Radical in the Gas Phase

Abstract

HO. radicals were produced in the gas phase by flash photolysis of water vapor (3%) in an atmosphere of hydrogen, helium, or argon containing ~2% oxygen. Water is dissociated in the first continuum to Hand OH, and O. converts the H atoms to HO •. Hydrogen nearly doubles the amount of HO. produced by converting OH to H. The absorption spectrum of HOI is a broad band with a peak at 2050 A. The molar extinction coefficient, Em • ., based on measurement of the H~, formed in the hydrogen system, is 1770± 150M-l· cm-l. The rate constant for the bimolecular combination reaction, HO.+HO.-->H.O.+0 2 , was evaluated as 5.7±0.5X1()9M-l·seC I at 298°K and for the reaction HO.+OH-->H 2 0+O., k=1.2±0.2X lOuM-I·see-l. From auxiliary measurements of the rate of 0 3 formation it was also found that, in the flash photolysis of O. (2%) in H2, hot 0 atoms react with H2 to form OH and H which are then converted to H02•

Theoretical Determination of the Rate Coefficient for the HO2 + HO2→ H2O2+O2Reaction: Adiabatic Treatment of Anharmonic Torsional Effects

“…The self-reaction of the hydroperoxy radical, HO 2 , is an important process in atmospheric and combustion chemistry. As such, it has been repeatedly studied over the last several decades.…”

The Kinetic Equations of Addition Processes by the Free-Radical Nonbranched-Chain Mechanism

“…The hydroperoxyl free radical 2 HO  [75][76][77][78] resulting from reaction 2 possesses an increased energy due to the energy released the conversion of the О=О multiple bond into the НО-О • ordinary bond. Therefore, before its possible decomposition, it can interact with a hydrogen or oxygen molecule as the third body via parallel (competing) reactions 3 and 4, respectively.…”

A New Mechanism of Free-Radical Nonbranched-Chain Oxidation: Oxygen as an Antioxidant

“…The O4 molecule was identified by NR mass spectrometry [45]. HO [46][47][48][49][50] resulting from reaction 2 possesses an increased energy due to the energy released the conversion of the О=О multiple bond into the НО-О…”