O:;
7782-44-7Relevant academic research and scientific papers
Measurements of the absorption line strength of hydroperoxyl radical in the ν3 band using a continuous wave quantum cascade laser
Sakamoto, Yosuke,Tonokura, Kenichi
, p. 215 - 222 (2012)
Mid-infrared absorption spectroscopy has been applied to the detection of the hydroperoxyl (HO2) radical in pulsed laser photolysis combined with a laser absorption kinetics reactor. Transitions of the ν3 vibrational band assigned to the O-O stretch mode were probed with a thermoelectrically cooled, continuous wave mid-infrared distributed feedback quantum cascade laser (QCL). The HO2 radicals were generated with the photolysis of Cl2/CH3OH/O2 mixtures at 355 nm. The absorption cross section at each pressure was determined by three methods at 1065.203 cm-1 for the F1, 131,13 ← 141,14 transition in the ν3 band. From these values, the absolute absorption cross section at zero pressure was estimated. The relative line strengths of other absorptions in the feasible emitting frequency range of the QCL from 1061.17 to 1065.28 cm-1 were also measured, and agreed with values reproduced from the HITRAN database. The ν3 band absorption strength was estimated from the analytically obtained absolute absorption cross section and the calculated relative intensity by spectrum simulation, to be 21.4 ± 4.2 km mol-1, which shows an agreement with results of quantum chemical calculations.
Investigation of the radical product channel of the CH3OCH 2O2 + HO2 Reaction in the Gas Phase
Jenkin,Hurley,Wallington
, p. 408 - 416 (2010)
The reaction of CH3OCH2O2 with HO 2 has been investigated at 296 K and 700 Torr using long path FTIR spectroscopy, during photolysis of Cl2/CH3OCH 3/CH3OH/air mixtures. The branching ratio for the reaction channel forming CH3OCH2O, OH, and O2 has been determined from experiments in which OH radicals were scavenged by addition of benzene to the system, with subsequent formation of phenol used as the primary diagnostic for OH radical formation. The dependence of the phenol yield on the initial peroxy radical precursor reagent concentration ratio, [CH 3OH]0/[CH3OCH3]0, is consistent with prompt OH formation resulting mainly from the reaction of CH3OCH2O2 with HO2, such that the inferred prompt yield of OH is well-correlated with that of CH 3OCH2OOH, a well-established product of the CH 3OCH2O2 + HO2 reaction. The system was fully characterized by simulation, using a detailed chemical mechanism which included other established sources of OH in the system. This allowed a branching ratio of k2c/k2 = 0.19 ± 0.08 to be determined. The results therefore provide strong indirect evidence for the participation of the radical-forming channel of the title reaction.
Linking ion and neutral chemistry in C-H bond electrophilic activation: Generation and detection of HO2. reactive radicals in the gas phase
Depetris, Giulia,Angelini, Giancarlo,Ursini, Ornella,Rosi, Marzio,Troiani, Anna
, p. 1455 - 1458 (2012)
The flip side: Both the charged and uncharged products formed by C-H bond electrophilic activation have been experimentally detected in the gas phase. The HO2. radical is formed by a process involving the prototypical oxygen-centered radical cation O2.+ and the methane derivative CH2F2. Copyright
Prompt HO2 formation following the reaction of OH with aromatic compounds under atmospheric conditions
Nehr, Sascha,Bohn, Birger,Wahner, Andreas
, p. 6015 - 6026 (2012)
The secondary formation of HO2 radicals following OH + aromatic hydrocarbon reactions in synthetic air under normal pressure and temperature was investigated in the absence of NO after pulsed production of OH radicals. OH and HOx (=OH + HO2) decay curves were recorded using laser-induced fluorescence after gas-expansion. The prompt HO2 yields (HO2 formed without preceding NO reactions) were determined by comparison to results obtained with CO as a reference compound. This approach was recently introduced and applied to the OH + benzene reaction and was extended here for a number of monocyclic aromatic hydrocarbons. The measured HO2 formation yields are as follows: toluene, 0.42 ± 0.11; ethylbenzene, 0.53 ± 0.10; o-xylene, 0.41 ± 0.08; m-xylene, 0.27 ± 0.06; p-xylene, 0.40 ± 0.09; 1,2,3-trimethylbenzene, 0.31 ± 0.06; 1,2,4-trimethylbenzene, 0.37 ± 0.09; 1,3,5- trimethylbenzene, 0.29 ± 0.08; hexamethylbenzene, 0.32 ± 0.08; phenol, 0.89 ± 0.29; o-cresol, 0.87 ± 0.29; 2,5-dimethylphenol, 0.72 ± 0.12; 2,4,6-trimethylphenol, 0.45 ± 0.13. For the alkylbenzenes HO2 is the proposed coproduct of phenols, epoxides, and possibly oxepins formed in secondary reactions with O2. In most product studies the only quantified coproducts were phenols whereas only a few studies reported yields of epoxides. Oxepins have not been observed so far. Together with the yields of phenols from other studies, the HO2 yields determined in this work set an upper limit to the combined yields of epoxides and oxepins that was found to be significant (≥0.3) for all investigated alkylbenzenes except m-xylene. For the hydroxybenzenes the currently proposed HO2 coproducts are dihydroxybenzenes. For phenol and o-cresol the determined HO2 yields are matching the previously reported dihydroxybenzene yields, indicating that these are the only HO 2 forming reaction channels. For 2,5-dimethylphenol and 2,4,6-trimethylphenol no complementary product studies are available.
Absolute Rate Constant of the Reaction OH+HO2->H2O+O2
Keyser, Leon F.
, p. 3667 - 3673 (1981)
The absolute rate constant of the reaction OH+HO2->H2O+O2 was determined by using the discharge-flow resonance fluorescence technique at 299 K and 1-torr total pressure.Pseudo-first-order conditions were used with HO2 concentrations in large excess over O
Production of H2O radical in the Track of High-Energy Carbon Ions
La Verne, Jay A.,Schuler, Robert H.
, p. 4171 - 4173 (1985)
The radiation chemical yields of H2O radical produced by irradiating water with 12C ions of 37-100-MeV initial energy have been determined. these data have been combined with previous values for lower energy carbon and helium ions to obtain the differential yields over the range 2-102 eV/Angstroem.The close similarly between the yields for helium and carbon ions of the same LET suggests that the reaction volume of interest extrends somewhat beyond the track core, especially for helium.LET appears to be a useful parameter to describe the production of H2O radicals in the tracks of heavy particles.
Track Effects in Radiation Chemistry: Production of HO2. in the Radiolysis of Water by High-LET (58)Ni Ions
La Verne, Jay A.,Schuler, Robert H.
, p. 6560 - 6563 (1987)
The yields of HO2. produced in the radiolysis of water by (58)Ni ions having energies up to 460 MeV have been determined.For these radiations the differential yields for HO2. production increase from 0.26 to 0.43 molecules/100 eV over an LET range of 260-520 eV/Angstroem.From these measurements a limiting yield of 0.57 molecules/100 eV is estimated for HO2. production by energy deposited in the track core at very high LETs.These studies demonstrate the feasibility of carrying out significant radiation-chemical studies with beams of particles having LETs in excess of 200 eV/Angstroem.
Mechanistic Investigation of the HO+HO2 Reaction
Kurylo, Michael J.,Klais, Odo,Laufer, Allan H.
, p. 3674 - 3678 (1981)
A steady-state photolysis experiment including mass-spectrometric end-product analysis was used to conduct a mechanistic investigation of the H(18)O+HO2 reaction system.The results obtained do not support the existence of a linear adduct reaction intermediate as suggested by a proposed pressure dependennce for the title reaction: HO+HO2->H2O+O2 (k1).An elaborate modeling analysis of the experiment best matches the observed product yields for values of k1 in the range 1*10-10-2*10-10 cm3 molecule-1 s-1.
Reaction of O2 with the hydrogen atom in water up to 350 °C
Janik, Ireneusz,Bartels, David M.,Marin, Timothy W.,Jonah, Charles D.
, p. 79 - 88 (2007)
The reaction of the H atom with O2, giving the hydroperoxyl HO2 radical, has been investigated in pressurized water up to 350 °C using pulse radiolysis and deep-UV transient absorption spectroscopy. The reaction rate behavior is highly non-Arrhenius, with near diffusion-limited behavior at room temperature, increasing to a near constant limiting value of ～5 × 1010 M-1 s -1 above 250 °C. The high-temperature rate constant is in near-perfect agreement with experimental extrapolations and ab initio calculations of the gas-phase high-pressure limiting rate. As part of the study, reaction of the OH radical with H2 has been reevaluated at 350 °C, giving a rate constant of (6.0 ± 0.5) × 108 M-1 s-1. The mechanism of the H atom reaction with the HO2 radical is also investigated and discussed.
Track Effects in Radiation Chemistry: Production of HO2(.) within the Track Core in the Heavy-Particle Radiolysis of Water
LaVerne, Jay A.,Schuler, Robert H.,Burns W. G.
, p. 3238 - 3242 (1986)
The radiation chemical yields of HO2(.) radicals produced by (1)H, (4)He, (7)Li, (9)Be, (11)B, (12)C, and (20)Ne ions having energies up to 35 MeV have been determined.At energies above 10 MeV the yield with protons approaches the value of 0.020 molecules/100 eV observed with fast electrons.The yield increases with increasing mass and decreasing energy of the irradiating particle and exceeds 0.2 molecules/100 eV for low-energy (9)Be, (11)B, (12)C, and (20)Ne ions.Extrapolation indicates an upper limit of 0.37 molecules/100 eV for more massive ions.We conclude that HO2(.) is produced mainly in the track core, so that HO2(.) production is a good probe of the dependence of core processes on particle characteristics.Comparison of the differencial yields observed for different particles having the same linear energy transfer (LET) shows that these yields are not strongly dependent on the irradiating particle.After correction for energy lost to ? rays, the LET dependence of the yield pertinent to the core is common to all of the particles studied, indicating that in this case the track has expanded to some extent before reaction occurs.
