Quantification of OH and HO ₂ radicals during the low-temperature oxidation of hydrocarbons by Fluorescence Assay by Gas Expansion technique

Abstract

•OH and •HO 2 radicals are known to be the key species in the development of ignition. A direct measurement of these radicals under low-temperature oxidation conditions (T = 550-1,000 K) has been achieved by coupling a technique named fluorescence assay by gas expansion, an experimental technique designed for the quantification of these radicals in the free atmosphere, to a jet-stirred reactor, an experimental device designed for the study of lowtemperature combustion chemistry. Calibration allows conversion of relative fluorescence signals to absolute mole fractions. Such radical mole fraction profiles will serve as a benchmark for testing chemical models developed to improve the understanding of combustion processes.

Progress in Understanding Low‐Temperature Organic Compound Oxidation Using a Jet‐Stirred Reactor

“…FAGE was initially developed for the quantification of hydroxyl (HO ● ) and hydroperoxyl (HO 2 ● ) radicals in the atmosphere. It has been coupled to a JSR by Blocquet et al to quantify these radicals during low‐temperature oxidation of n ‐butane. This method is based on the detection of ● OH radicals by laser‐induced fluorescence at 308 nm.…”

“…At the center of this was located the stainless steel cone with an orifice of 400 μm: the FAGE inlet. The calibration method had to be adapted to handle the large JSR radical concentrations (ppm) compared to the typical very low atmospheric ones (ppt) and is certainly subject to large uncertainties.…”

Detection of HO2in an atmospheric pressure plasma jet using optical feedback cavity-enhanced absorption spectroscopy

“…The hydroperoxyl radical, HO 2 , plays an important role in atmospheric chemistry, as it is a key radical in the OH-induced oxidation cycle which controls virtually all of the daytime oxidative chemistry in the lower atmosphere and is therefore responsible for the transformation of primary emissions into secondary pollutants [1]. Furthermore, HO 2 is prevalent in hydrocarbon combustion [2][3][4] and in dielectric barrier discharges utilized for the purification of water [5] or the removal of volatile organic compounds in air [6].…”

“…Furthermore, HO 2 is prevalent in hydrocarbon combustion [2][3][4] and in dielectric barrier discharges utilized for the purification of water [5] or the removal of volatile organic compounds in air [6].…”

Cold and intense OH radical beam sources

“…7,8 One of the most widely studied free radical species is hydroxyl OH, which holds an essential role in biochemical, interstellar, atmospheric, and combustion science. [9][10][11][12] Three major approaches have been used to generate OH radicals with the molecular beam technique: photolysis, 13 14,15 and electrical discharge. [16][17][18] Of these, the discharge method is the most cost-efficient, simplest, and the most broadly applicable.…”