We report absolute electron-impact ionization cross sections from threshold to 30 eV for the formation of the parent ions from free radicals. A microwave discharge is used as a source to produce a large amount of these free radicals, and measurements are mainly performed by means of mass spectrometry. We detail the method used to ...

Ammonia reactions with CH radicals, investigating quantitative aspects of hydrogen cyanide formation

Radical cations from methyl iodide CH/sub 3/I/sup .+/, and (CH/sub 3/I therefore ICH/sub 3/)/sup +/ are shown to be excellent oxidants with a one-electron redox potential presumably greater than or equal to +2 V. Absolute rate constants in the order of 10/sup 9/ M/sup -1/ have been determined for their reactions ...

Spectral and radiation parameters of chemiluminescence have been measured in the thermal decomposition of methyl nitrite and methyl nitrate in shock waves. It has been established that the emission spectrum corresponds to the chemiluminescence spectrum in the process of radiation-induced disproportionation of CH/sub 3/O radicals; the mean radiation rate ...

... Hydrogen iodide acted as an excellent radical "trap" for these radicals. No spontaneous decomposition of acetyl radicals was observed. Relative ...

... Title : Absolute Concentration Measurements of Free Radicals in Flames by Absorption Spectroscopy. Descriptive Note : Final rept. ...

A comprehensive study of several atmospheric degradation routes for two hydrofluoroalcohols, CF(3)(CH(2))(x=1,2)CH(2)OH, is presented. The gas-phase kinetics of their reactions with hydroxyl radicals (OH) and chlorine (Cl) atoms are investigated by absolute and relative techniques, respectively. The ...

... Title : ABSOLUTE RATE CONSTANTS FOR HYDROCARBON OXIDATION. XII. RATE CONSTANTS FOR SECONDARY PEROXY RADICALS,. ...

Flash photolysis (FP) coupled to resonance fluorescence (RF) was used to measure the absolute rate coefficients (k(1)) for the reaction of OH(X(2)?) radicals with diiodomethane (CH(2)I(2)) over the temperature range 295-374 K. The experiments involved time-resolved RF detection of the OH (A(2)?(+)?X(2)? transition at ? = 308 nm) ...

... Accession Number : AD0252660. Title : GASEOUS DETONATIONS. XIV. THE CH RADICAL IN ACETYLENE OXYGEN-DETONATIONS. ...

Photodissociation of acetaldehyde (CH3CHO) at 266 nm produced CH3 and HCO radicals, and single-photon vacuum ultraviolet ionization was used to record velocity map ion images of both CH3+ and HCO+. Comparison of the translational energy distributions from both species indicates that secondary fragmentation of HCO ...

The frequencies, wavelengths, and line strengths for transitions of the CH molecule at microwave and

A method for the production of t-butoxy radicals by the photolysis of t-butyl hypochlorite was employed to determine the absolute rate of combination of t-butoxy radicals at room temperature and to determine the absolute rate of hydrogen atom abstraction ...

Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P(3/2)) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr of air or N2; diluents at 295 +/- 2 K were ...

The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH{sub 3} photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron ...

Using pulse radiolysis and steady-state gamma-radiolysis techniques, it has been established that, in air-saturated aqueous solutions, peroxyl radicals CH 2HalOO (*) (Hal = halogen) derived from CH 2Cl 2 and CH 2Br 2 react with dimethyl selenide (Me 2Se), with k on the order of 7 x 10 (7) M (-1) s (-1), to form HCO ...

The reaction of tert-butoxy radicals with diphenylmethanol and with cumene was examined using nanosecond laser flash photolysis techniques in order to determine the absolute values of the rates of reaction of the radicals. The absolute rate measured for both substrates compare favorably with the values for the ...

The authors research goal was to develop nonintrusive, laser-based optical diagnostic tools for the investigation of trace amounts of molecular species in hostile environments such as plasmas, flashes, flames and other combustion forms. By extending their study on spectroscopic applications of degenerate four-wave mixing (DFWM), they proposed to exploit a new absorption technique, Cavity Ring-Down ...

... of d(CH3CHO)/dt to calculate the concentration of C4H9O2 radicals, and hence ... activation energy for the isomerisation of the peroxy radical into the ...

A pyrolysis source coupled to a supersonic expansion has been used to produce the CH3 radical from two precursors, iodomethane CH3I and nitromethane CH3NO2. The relative ionization yield of CH3 has been recorded at the SOLEIL Synchrotron Radiation source in the range 9.0-11.6 eV, and its ...

The absolute rate constants for the reaction between the NH2 free radical and acetylene and ethylene

Methane photolysis has been performed at the two Vacuum UltraViolet (VUV) wavelengths, 121.6 nm and 118.2 nm, via a spectrally pure laser pump-probe technique. The first photon is used to dissociate methane (either at 121.6 nm or at 118.2 nm) and the second one is used to ionise the CH(2) and CH(3) fragments. The radical products, ...

Absolute rate constants were measured for the reactions of cumylperoxy radicals with a number of hydrocarbons. The cumylperoxy radicals were produced from cumene hydroperoxide. Sufficient hydroperoxide was present to ensure that only cumylperoxy radicals ...

The methyl radicals trapped in single crystals of CH$sub 3$COOLix2H$sub 2$O irradiated at 77 degreeK have been studied by ENDOR. The proton hyperfine coupling tensor was determined to be (-21.30, -20.57, -21.61) G. The absolute sign of the coupling was determined in referring to the nuclear dipole--dipole interaction. The ...

Two pathways to cyclization products from 1,6-heptadiene and iodoperfluoroalkanes ((RF)I) were discovered. Ring closure of the intermediate radical, (RF)CH2C=H(CH2)3CH=CH2, may occur or the open-chain adduct, (RF)CH2CHI(CH2)3CH=CH2, may itself rearrange ...

The absolute photoionization cross section of the methyl radical was determined relative to that of NO at photon energies of 10.54 eV using the CH(3) + NO(2) --> CH(3)O + NO reaction. Kinetics of this reaction was studied in a fast flow reactor coupled with VUV laser photoionization. Simulation of the kinetics ...

The reactions, energy transfer, and dynamics of free radicals produced by ultraviolet laser photolysis were studied. The measurements on free radical chain reactions, absolute rate coefficients, and photofragmentation dynamics were carried out by time-resolved infrared emission spectroscopy. The dynamics of hot methyl ...

... Title : Kinetics of CH Radicals With O2: Evidence for CO-Chemiluminescence in ... A trace amount of CMBr3 vapor was photo-decomposed in a pulsed ...

Rate constants have been measured for the gas phase reaction of the hydroxyl radical (OH) with CH3Br

... Accession Number : ADA133815. Title : A Study of the CH2NO2 Radical Using a Multiconfigurational Self-Consistent Field Approach. ...

Acetaldehyde was photodissociated with near UV laser light, and the methyl (CH_3) and formyl (HCO) radical fragments were photoionized with vacuum ultraviolet (VUV) light. The fragments were detected by using both time of flight mass spectrometry and velocity ion map imaging. With the former technique, simultaneous detection of both fragments provided the ...

The gas-phase reaction of atomic chlorine with diiodomethane was studied over the temperature range 273-363 K with the very low-pressure reactor (VLPR) technique. The reaction takes place in a Knudsen reactor at pressures below 3 mTorr, where the steady-state concentration of both reactants and stable products is continuously measured by electron-impact mass spectrometry. The ...

A technique for the selective measurement of atmospheric HO2 and RO2 using peroxy radical chemical amplification coupled to laser-induced fluorescence NO2 detection (PERCA-LIF) technique is proposed. By pulling the air through a filled pre-inlet advantage can be taken of the higher heterogeneous loss rate of HO2 relative to CH3O2. Pre-inlet conditions have ...

A technique for the selective measurement of atmospheric HO2 and RO2 using peroxy radical chemical amplification coupled to laser-induced fluorescence NO2 detection (PERCA-LIF) is demonstrated. By pulling the air through a filled pre-inlet advantage can be taken of the higher heterogeneous loss rate of HO2 relative to CH3O2. Pre-inlet conditions have been ...

The hydroxymethyl radical, CH/sub 2/OH, has been detected by the method of resonance-enhanced multiphoton ionization mass spectroscopy. Radicals were produced via hydrogen abstraction from CH/sub 3/OH by fluorine atoms in a discharge flow reactor. Tunable laser radiation between 427 and 490 nm ionized the ...

Low pressure CH4, CH4/H2, and H2 plasma beams were generated by a 13.56 MHz inductively coupled radio frequency (rf) plasma with a magnetic field (~300 G) to utilize them as radical sources for the epitaxial growth of diamond. The threshold ionization technique using a quadrupole mass spectrometer has been employed to measure the ...

The epr spectra of a single crystal of C36H74, hexatriacontane, have been analyzed. The radicals CH3CH(CH2)33CH3 and R'CH2CHCH2R double prime are formed after gamma irradiation at 195K in a ratio of approximately 3 to 1. A computer-assisted method was app...

Electron collision cross sections for highly reactive CFx (x = 1-3) radicals are required to model technological plasmas. In spite of their importance to industry, experimental studies of electron interactions with CFx radicals are rarely reported in the literature. A new apparatus for measuring absolute elastic differential cross ...

Formation of free radicals under UV-irradiation of egg phosphatidyl choline, and synthetic phosphatidyl cholines and their analogs, as well as of their model compounds was studied. When saturated fat lipids are UV-irradiated radicals--CH2CH2 are accumulated at the expense of the breakage ...

A complementary experimental and quantum chemical study has been undertaken on the reactivity, formation and properties of transients generated in the reaction of selected organic selenides with hydroxyl radicals, oxide radical ions, hydrated electrons and hydrogen atoms in aqueous solution. A detailed study of the OH and O (-) reactions with Me(2)Se ...

The triphenylimidazolyl radical is capable of dehydrogenating ..beta..-dicarbonyl compounds which are characterized by a high content of the enolic form. The dehydrogenation rate increases with increase in the pK/sub a/ value of the enol. The formation of short-lived radicals during the dehydrogenation of CH acids by ...

... Title : ELECTRON PARAMAGNETIC RESONANCE OF THE CH2CO2(-) RADICAL IN IRRADIATED ZINC ACETATE DIHYDRATE. ...

We measure cavity ringdown spectra of the A{sup 2}{Delta}-X{sup 2}II transition of the methylidyne (CH) radical in a series of rich low-pressure methane-oxygen-argon flames and demonstrate that the technique is sensitive, quantitative, and straightforward in its implementation and interpretation. As a line-of-sight technique, it complements imaging ...

Film deposition in pulsed inductively coupled plasmas is investigated using methane as precursor gas. The densities of neutrals as well as ion and radical fluxes are quantified using mass spectrometry. Plasma composition is uniquely determined by the mean dissipated energy per source gas molecule in the plasma, Emean. Film growth rates are measured by in situ real-time ...

The unimolecular reactions of the isomeric ions C2H5C(OH)CH2(+) radical and CH3CHC(OH)CH3(+) radical are explicable in terms of stepwise rearrangement of individual hydrogen atoms leading to the ketonic ion CH3CH2(-)COCH3(+) ...

The lifetime of the lignin radical model compound, 1-phenyl-2-phenoxyethanol-1-yl, PhC?(OH)CH2-OPh is several orders of magnitude greater than suggested by the previous experimental studies. The ketyl radical is competitively trapped by thiophenol to yield PhCH(OH)CH2-OPh in competition with? -scission to yield ...

We report high resolution infrared spectra in the C-H stretch region for small hydrocarbon radicals isolated in helium nanodroplets. Stark Spectroscopy of the symmetric CH2 stretch of the ethyl radical provides the first experimentally measured dipole moment for this species.

Recent progress is described on the study of the reactions, energy transfer, and dynamics of free radicals produced by ultraviolet laser photolysis. These measurements on free radical chain reactions, absolute rate coefficients, and photofragmentation dynamics are carred out by the method of time-resolved infrared emission ...

Absolute rate data for the Cl({sup 2}P{sub J}) + CH{sub 4} {yields} HCl + CH{sub 3} reaction have been obtained from 218 to 298 K by using the discharge flow resonance fluorescence technique in helium at 1 Torr total pressure. The result at 298 K is (10.1 {+-} 0.6) x 10{sup {minus}14} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}. ...

This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H2COCH)CH2Cl. The three dominant photoproduct channels analyzed are c-(H2COCH)CH2+Cl, c-(H2COCH)+CH2Cl, and C3H4O+HCl. In the second channel, the ...

This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H(2)COCH)CH(2)Cl. The three dominant photoproduct channels analyzed are c-(H(2)COCH)CH(2)+Cl, c-(H(2)COCH)+CH(2)Cl, and C(3)H(4)O+HCl. In the second channel, the ...

The absolute photoionization cross section of C(2)H(5) has been measured at 10.54 eV using vacuum ultraviolet (VUV) laser photoionization. The C(2)H(5) radical was produced in situ using the rapid C(2)H(6) + F ? C(2)H(5) + HF reaction. Its absolute photoionization cross section has been determined in two different ways: first using the ...

-Kiracofe et al. described two possible paths leading to ethylene oxide and hydroxy radical and one leading to acetaldehyde and hydroxy radical. Figure 1 shows the PES's of the three ethylene-producing reaction paths of oxidation of ethyl radical to produce ethylene, along the concerted-elimination path ...

Recent progress is described on the study of the reactions, energy transfer, and dynamics of free radicals produced by ultraviolet laser photolysis. Free radical chain reactions are analyzed by fully time-resolved techniques involving infrared emission spectroscopy. Some of the most recent results include a mesurement of the low resolution infrared ...

The line strengths of five Q-branch lines of the first hot band of the out-of-plane bending vibration (2(1)(2)) of the methyl radical, CH 3, have been measured using infrared laser absorption spectroscopy. The spectra of the radical were measured in situ in a microwave discharge using ditertiary butyl peroxide, diluted in argon as the ...

Radical-chain halogenations of 2-bromo- and 2-chlorobutanes, optically active and deuterium substituted, provide insight into the nature of the radical intermediates. Absolute configurations are assigned for the optically active compounds. There is also d...

... Accession Number : AD0751310. Title : The Absolute Measurement of Rate Constants for Some Kay Reactions Involving Free Radicals. ...

Kinetics of the ethynyl (C(2)H) radical reactions with H(2), D(2), CH(4) and CD(4) was studied over the temperature range of 295-396 K by a pulsed laser photolysis/chemiluminescence technique. The C(2)H radicals were generated by ArF excimer-laser photolysis of C(2)H(2) or CF(3)C(2)H and were monitored by the chemiluminescence of ...

Dilute mixtures of n-octanal in synthetic air (up to 100 ppm) were photolyzed with fluorescent UV lamps (275-380 nm) at 298 K. The main photooxidation products were 1-hexene, CO, vinyl alcohol, and acetaldehyde. The photolysis rates and the absolute quantum yields were found to be slightly dependent on the total pressure. At 100 Torr, ?(100) = 0.41 � 0.06, whereas at 700 ...

radicals, exponents, scientific notation, absolute values, fractions, ... 12.1.2 Express the equivalent forms of numbers using exponents, radicals, ...

A comprehensive study of microwave (MW) activated B2H6/CH4/Ar/H2 plasmas used for the chemical vapor deposition of B-doped diamond is reported. Absolute column densities of ground state B atoms, electronically excited H(n = 2) atoms, and BH, CH, and C2 radicals have been determined by cavity ring down spectroscopy, ...

By means of time-resolved Fourier transform infrared absorption spectroscopy, we have investigated the 193 nm photodissociation and photoisomerization dynamics of the prototype molecule of ?,?-enones, acrolein (CH2=CHCHO) in CH3CN solution. The primary photolysis channels and absolute branching ratios are determined. The most probable ...

The isotopic method of determining absolute age is the most accurate and .... Another method of relative age dating involves the relative abundance of ...

Concentration profiles of low pressure, slightly lean CH4-O2-Ar flames have been measured in situ for the following unstable species: oxygen atom, hydrogen atom, hydroxyl radical, methyl radical, and formyl radical. (Modified author abstract)

.96) #12;Aromatic Reaction With Hydroxyl Radical Toluene oxidation CH3 H OH O O CH3 H OH CH3 OH H2C O OCH2 Toluene o2 + OH H2O + OH (12.97) #12;Aromatic Reaction With Hydroxyl Radical Benzylperoxy radical reaction + NO + O2 HO2 + NO (12.98) Toluene-hydroxyl ...

Radiolysis of crystalline methanol and the structure of radicals produced have been studied at 4.2 K using electron spin resonance spectroscopy. It has been observed for the first time that CH/sub 3/O and CH/sub 3/ are formed as major products together with conventional CH/sub 2/OH in pure ...

Surface-generated gas-phase radicals, which are the subject of this study, may function as important intermediates in several important partial and complete oxidation reactions. Two examples are the role of CH{sub 3} radicals in the oxidative coupling of CH{sub 4} and the role of OH radicals in ...

exponents, radicals, percents, scientific notation, absolute value, rational numbers, and irrational numbers) using multi-step and real world problems. ...

... have devised for measuring the absolute H density involves absorption spectroscopy on the Lyman-alpha transition of ...

Millersville University. D. C. Tardy. University of Iowa. 1. Introduction. The methyl free radical (CH3) has been observed in the atmospheres of Saturn and ...

This investigation covers the development of nonintrusive, laser-based optical diagnostic tools for the measurement of trace amount molecular species in hostile, reactive environments such as plasmas. Two- photon laser induced fluorescence (LIF) spectroscopy is applied to obtain the temperature of atomic hydrogen and Cavity Ring-Down Spectroscopy (CRDS) to measure absolute ...

We have studied the gas-phase photolysis of 4-oxo-2-pentenal by laser photolysis combined with cavity ring-down spectroscopy. Absorption cross sections of cis- and trans-4-oxo-2-pentenal have been measured in the 190-460 nm region. The product channel following 193, 248, 308, and 351 nm photolysis of 4-oxo-2-pentenal was investigated. The HCO radical is a photodissociation ...

Comparisons are drawn between spatially resolved absorption spectroscopy data obtained for a 6.4 kW dc arc jet reactor, operating with Ar/H2/CH4 gas mixtures, used for deposition of thin, polycrystalline diamond films, and the results of a two-dimensional (r,z) computer model incorporating gas activation, expansion into the low pressure reactor, and the chemistry of the ...

emission) and hydroxyl radical in a vast cloud surrounding the comet, ... In addition, CH3CN, HCN, and corresponding radicals and ions are common ...

... we ex- amine the reaction kinetics for the recombination of H atoms with two such resonantly stabilized radicals; the allyl radical (CH2CHCH2) and ...

The energy partitioning in CN radicals produced by the vacuum ultraviolet photodissociation of HC2CN

methyl radicals are unreactive. (There reactions have been ... reaction of the methyl radical with oxygen. The data are consistent ...

The role of peroxides in radiobiology is reviewed. Topics discussed include the chemistry and physics of radicals, their formation, recognition, and reactivities, with emphasis on radioinduced free radicals in biological systems. (C.H.)

Selected elementary reactions of CH(sub 3) radicals in an isothermal flow system in the gaseous phase were investigated by means of LMR.

Twelve wildlife toxicology laboratories participated in an interlaboratory survey of cholinesterase (ChE) assays to determine comparability of absolute ChE values and estimates of ChE inhibition from organophosphorus insecticide-dosed birds and to examine the type and consistency...

photon impact the CH4 molecule is distorted bringing at least two H atoms close enough together .... total emission spectra resulting from CH4 irradiated by ...

The reactions of the CH radical with several unsaturated hydrocarbons C2H2 (acetylene), C2H4 (ethylene), C3H4 (methyl-acetylene and allene), C3H6 (propene) and C4H8 (trans-butene) were studied at room temperature, in a low-pressure fast-flow reactor. CH(X2pi, v = 0) radicals were obtained from the reaction of CHBr3 ...

Measurement of electronic g-factors (g) from radicals in irradiated organic crystals is generally difficult because the overall EPR pattern is usually the composite of several components, e.g., from multiple radicals and from multiple magnetic sites. However, when an ENDOR line is fully resolved, the method of ENDOR-induced EPR (EI-EPR, or EIE) in ...

Rotational constants and dipole moments for linear-chain radicals CnCH and CnN are estimated using a

... Accession Number : AD0762655. Title : Irradiated Betaine Hydrochloride: The Free Radical, N(CH3)3(+),. Corporate Author ...

May 15, 1999 ... Peterson, K.A., Oh, D.B., High-sensitivity detection of CH radicals in flames by use of a diode-laser-based near-ultraviolet light source, ...

... Abstract : An electron spin resonance analysis of irradiated zinc acetate dihydrate, Zn(CH3COO)2.2H2O has been made. The methyl radical,.CH3 ...

... R. X + CH3---- R + CH3 1 13. Relative Rates of H Abstraction and X Abstraction 27 U4. Adition of CE3 Radical. Adition of CF3 Radicals 32-33 15. ...

{beta}-Hydroxycarbonyls can be formed from the gas-phase reactions of alkenes with the OH radical, both in the presence and in the absence of NO. To date, because of analytical difficulties, few data have been reported for the formation of this class of compound from the reactions of the OH radical with alkenes. The authors have determined that ...

The methoxymethyl radical, CH(3)OCH(2), is prepared via hydrogen photodissociation from dimethyl ether during codeposition of CH(3)OCH(3) in excess argon at 4 K with laser-excited metal plume radiation. The spectrum of this radical is characterized by four infrared absorptions at 1468.1, 1253.9, 1226.6, and 944.4 ...

Radical Addition Rate Constants to Acrylates and Oxygen: R-Hydroxy and R-Amino Radicals Produced photolysis of R-hydroxy and R-amino ketones, which are used as photoinitiators in free radical polymerization, lead to the generation of a series of nucleophilic R-hydroxy and R-amino radicals. ...

A general method for the measurement of absolute rate constants for the termination of photochemically produced organic free radicals in solution has been developed. Radicals are generated in the cavity of an EPR spectrometer by high intensity uv irradiat...

The absolute rate constant for the reaction of ground state oxygen atoms with methyl radicals is reported. The methyl radicals were generated by the reaction of oxygen atoms with ethylene in a fast flow reactor, and were detected by a photoionization mass...

We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G

... Accession Number : AD0464325. Title : DEUTERIUM ISOTOPE EFFECTS ON RATES OF METHYLENE RADICAL INSERTION INTO CH BONDS. ...

... Descriptors : *CHEMICAL REACTIONS, *PHENYL RADICALS, *ACETYLENES, *RHODIUM COMPOUNDS, ACTIVATION, BENZENE, REACTION ...

This work determines the dissociation barrier height for CH2CHCO-->CH2CH+CO using two-dimensional product velocity map imaging. The CH2CHCO radical is prepared under collision-free conditions from C-Cl bond fission in the photodissociation of acryloyl chloride at 235 nm. The nascent ...

This work determines the dissociation barrier height for CH2CHCO --> CH2CH + CO using two-dimensional product velocity map imaging. The CH2CHCO radical is prepared under collision-free conditions from C-Cl bond fission in the photodissociation of acryloyl chloride at 235 nm. The nascent ...

Cavity ring-down spectroscopy (CRDS) was applied in several fuel-rich, one-dimensional, premixed C3H6/O2/Ar flames at 50 mbars (37.5 torr) to measure absolute OH, HCO, and CH21 concentration as well as temperature as a function of stoichiometry. Although these flames near the sooting limit present a complex chemical environment, significant spectral ...

The formation of radicals in irradiated methyl and ethyl acetates and formates and their deuterated analogs was studied using nitroso compounds and nitrone. After irradiation at 77K only adducts with the radicals CH/sub 2/COOR, COOR, and MeCOOCHR are observed, but on irradiation in the liquid phase the radicals ...

Rate coefficients, k, for the gas-phase reaction of the OH radical with (CH(3))(3)COOH (tert-butyl hydroperoxide) were measured as a function of temperature (206-375 K) and pressure (25-200 Torr (He, N(2))). Rate coefficients were measured under pseudo-first-order conditions using pulsed laser photolysis to produce OH and laser induced fluorescence ...

by reactions with C3H6 forming C3H6OH (hydroxy alkyl radicals), HCHO forming HCO, NO2 forming HNO3 is the conversion of NO to NO2 by the HAP radicals. also include CH3CH(OH)CH2O and CH3CH(O)CH2OH (-hydroxy alkoxy by the reaction of O2 with hydroxy alkyl ...

... The OH + 2BU reaction products and yields observed were: methyl ethyl ketone (MEK, 60 +/- 2%, CH3CH2C(=O)CH3 and acetaldehyde (29 +/- 4 ...

We report new measurements of the absorption oscillator strength for several CH3 transitions in the vacuum ultraviolet (VUV). The methyl radical (CH3) is important in a variety of systems including flames and diamond deposition reactors. The oscillator st...

MLS/Aura L2 Methyl Chloride (CH3CL) Mixing Ratio V003 ML2CH3CL at GES DISC ... data at different temperatures for 77 atmospheric trace gases and radicals. ...

Triple stage threshold ionization mass spectrometry is successfully implemented in an Ar/C{sub 2}H{sub 2} expanding thermal plasma setup. More than 20 hydrocarbon radicals and molecules formed in the plasma, including for example the C{sub 2}H, C{sub 3}, C{sub 3}H, and C{sub 3}H{sub 2} radicals or C{sub 3}H{sub 4} or C{sub 4}H{sub 2} molecules, are ...

Direct generation of a benzyl radical by C-H bond activation of toluenes and the addition reaction of the resulting radical to an electron deficient olefin were developed. The reaction of dimethyl fumarate with toluene in the presence of Et(3)B as a radical initiator at reflux afforded 2-benzylsuccinic acid ...

Symmetry adapted cluster expansion configuration interaction theory is used to determine the isotropic hyperfine coupling constants (HFCCs) for the radicals H2O(+), CH2O(+), CH3O, CH3NH, CH3CH2, and CH3OCH3(+). Calculated values are shown to agree well ...

The purpose of this research was to produce, by photolysis, sufficient quantities of the acetonitrile free radical (CH2CN) and to obtain its infrared spectrum. Production of the free radical was attempted by photolysis of solid iodoacetonitrile (ICH2CN) a...

The Re(CO)/sub 5/ radical has been generated in the pulse radiolysis of a variety of organorhenium compounds in ethanol solution as well as in the flash photolysis of Re/sub 2/(CO)/sub 10/ in isoctane solution. This radical exhibits an optical absorption band in the visible region with a maximum at 535 nm and a molar extinction coefficient, in ethanol, of ...

Absolute rate constants for the reaction of tri-tert-butylphenoxyl radical (ArO*) with (TMS)(3)SiH were measured spectrophotometrically in the temperature range 321-383 K. Rate constants for the hydrogen abstraction from (TMS)(3)SiH by diarylaminyl radicals of type (4-X-C(6)H(4))(2)N* were determined by using a method in which the ...

Systematic ab initio calculations of potential energy surfaces for the reactions of NH{sub 2} with various alkanes (CH{sub 4}, C{sub 2}H{sub 6}, C{sub 3}H{sub 8}, and i-C{sub 4}H{sub 10}) which involve abstraction of a hydrogen atom from primary, secondary, and tertiary C-H bonds have been performed using the G2M method. The calculated activation barrier ...

Reductive dehalogenation of 5-bromouracil by aliphatic organic radicals CO2?, CH2OH, CH(CH3)OH, and CH(CH3)O? have been studied in oxygen free aqueous solutions in the presence of organic additives: formate, methanol or ethanol. For radicals production 60Co ?-radiolysis was employed and the ...

Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with ethylene glycol diacetate, CH3C(O)O(CH2)2OC(O)CH3, in 700 Torr of N2/O2 diluent at 296 K. The rate constants measured were k(Cl + ...

The OH + CH(3) product channel for the photodissociation of CH(3)OH at 157 nm was investigated using the velocity map imaging technique with the detection of CH(3) radical products via (2+1) resonance-enhanced multiphoton ionization (REMPI). Images were measured for the CH(3) formed in the ...

A comprehensive study of microwave (MW) activated CH4/H2/Ar plasmas used for diamond chemical vapor deposition is reported, focusing particularly on the effects of gross variations in the H2/Ar ratio in the input gas mixture (from H2/Ar mole fraction ratios of > 10:1, through to ~1:99). Absolute column densities of C2(a) and CH(X) ...

The high-resolution proton magnetic resonance spectra of ethyl acetylene and ethyl mercaptan were studied at 40 Mc and 60 Mc. Theoretical analysis of these spectra as systems of the A/sub 3/B/sub 2/C type enables the relative signs of the proton-proton spin coupling constants in these molecules to be determined. It is shown that the spin coupling constants J/sub ...

A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular ...

Several examples of laser {ital in} {ital situ} monitoring of combustion processes are presented. Using a frequency modulated {sup 13}CO{sub 2} waveguide laser, {ital in} {ital situ} concentrations of NH{sub 3} down to 1 ppm were measured at temperatures up to 600 {degree}C in waste incinerators and power or chemical plants. Following ignition of CH{sub 3}OH--O{sub 2} mixtures ...

A pulsed core-sampling photofragment translational spectroscopy (PTS) method with a long time-delay, which allows an extremely high kinetic energy resolution, is presented in this article. More commonly applying a short time delay between laser and pulsed acceleration electric field leads to a low kinetic energy resolution for the pulsed core-sampling method. This low kinetic energy resolution ...

In order to investigate the role of radicals such as CH_3, CF_x, SiHx (x=1 ~3) in the plasma process, the absolute densities of radicals have been measured by using infrared diode laser absorption spectroscopy (IRLAS). Moreover, we have successfully measured the relative density of C atom in the inductive coupled ...

The reaction of peroxide radicals of the (CH/sub 3/)/sub 3/CO/sub 2/ and or CH/sub 3/O/sub 2/ type with the products of the decomposition of tertiary butyl hydroperoxide on the surface of the metalloporphyrin catalyst copper coproporphyrin (CuCP) was studied by the method of kinetically freezing out the radicals in ...

Understanding hydrocarbon species profiles and transport in outer planet atmospheres measured from probes such as Cassini or telescopes such as ISO requires photochemical models with accurate low temperature and pressure kinetics. We apply a sensitivity analysis technique to identify the key controlling reactions for various species, which require evaluation, theoretical extrapolation, and/or ...

The gas-phase ion/molecule chemistry of the z-CHNC and z-CHCN radical anions formed in the reactions of the Oz- ion with CH3NC and CH3CN respectively, has been studied by Fourier transform ion cyclotron resonance mass spectrometry. The gas-phase acidity, [Delta]H0acid, of the zCH2NC radical is ...

Thermal cleavage processes of N-methylmorpholine-N-oxide monohydrate (NMMO) were observed in pure NMMO as well as in cellulose/NMMO solutions by ESR at temperatures of the industrial Lyocell process ( approximately 370K). Generated radicals were attributed to the alkylnitroxyl type radicals -CH(2)-NO-CH(3) in NMMO ...

Absolute yields of CO, CO{sub 2}, and H{sub 2}CO formed in reaction of triplet methylene ({tilde X} {sup 3}B{sub 1} {triple_bond} CH{sub 2}) with O{sub 2} were determined using a flash kinetic spectrometer. CH{sub 2} radicals were generated by excimer laser photolysis of ketene and product formation was monitored ...

Methyl radical CH3Br. See Methyl bromide CH3CCl3. See Methylchloroform CH3I. See Methyl iodide CH3O2. See oxidation mechanism 209 rise since preindustrial times 113 Methyl bromide (CH3Br) 106 atmospheric lifetime

The pure rotational spectrum of the isotopically substituted methoxy radical /sup 13/CH/sub 3/O was observed in the millimeter- and submillimeter-wave region. The /sup 12/CH/sub 3/O radical was also studied in the same wavelength region and the molecular parameters of the previous work were reexamined. It was found ...

An EPR study has been carried out to investigate the structure and behaviour of the free radical formed ?-irradiated l-alaninamide hydrochloride, dl-glutamic acid monohydrate and N-(2-carboxyethyl) iminodiacetic acid powders at room temperature. The observed paramagnetic species have been attributed to the CH(3)?HCONH(2), ...

Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-CF(3)CH?CHCF(3) (cis-1,1,1,4,4,4-hexafluoro-2-butene) were measured under pseudo-first-order conditions in OH using pulsed laser photolysis (PLP) to produce OH and laser-induced fluorescence (LIF) to detect it. Rate coefficients were measured over a range of temperatures (212-374 ...

Pulsed lasers were used in this work to photofragment molecules or to initiate chain reactions. One of the major advances was the availability of high-powered rare gas halide excimer lasers. In addition, pulsed Nd:YAG lasers and dye lasers were used throughout. Results include: generalized kinetic formulations of the problem of laser-initiated chain reactions. Several studies were carried out to ...

This article discusses and compares various methods for defining and measuring radical stability, including the familiar radical stabilization energy (RSE), along with some lesser-known alternatives based on corrected carbon-carbon bond energies, and more direct measures of the extent of radical delocalisation. As part of this work, a ...

Dimethyl sulfoxide (DMSO) is the major sulfur-containing constituent of the Marine Boundary Layer. It is a significant source of H2SO4 aerosol/particles and methane sulfonic acid via atmospheric oxidation processes, where the mechanism is not established. In this study, several new, low-temperature pathways are revealed in the oxidation of DMSO using CBS-QB3 and G3MP2 multilevel and B3LYP hybrid ...

Absolute rate coefficients are reported for the room temperature reactions of deuterated methyl radicals with HI and HBr, CD/sub 3/ + HI (HBr) ..-->.. CD/sub 3/H + I(Br). Excimer laser photolysis of CD/sub 3/I is used to generate methyl radicals, and time-resolved infrared chemiluminescence from the CH stretch ...

Petroleum may be recovered from petroleum containing formations having high salinity and/or high temperature by injecting into the formation an aqueous fluid containing an effective amount of a surface active agent characterized by the formula: R-O-(A-O)N-(CH2-CH(-CH2-O-CH2-CH2-SO3X)-O)M-H wherein R is an alkyl or ...

with free radicals of different chemical nature (TEMPO, �P(O)(OiPr)2, �Re(CO)5, �MoCp(CO)2, �WCp(CO)3, �CH2 silyl radicals stabilized by delocalization. The first synthetic results of free radical addition of stable germylene 3 with free radicals with different chemical structure (eq ...

The dissociation dynamics of methylsulfonyl radicals generated from the photodissociation of CH(3)SO(2)Cl at 193 nm is investigated by measuring product velocities in a crossed laser-molecular beam scattering apparatus. The data evidence three primary photodissociation channels of the precursor: S-Cl fission to produce Cl atoms and ground electronic state ...

Absolute excitation functions for excited fragments resulting from electron bombardment of H2O, NH3,

Rate constants of various allyl radical reactions have been measured at combustion relevant temperatures of 1000 to 1400 K. Time resolved absorption spectroscopy was used under reflected shock wave conditions in highly diluted mixtures of the reagents in argon. Studies on the thermal dissociation of 1,5-hexadiene as a precursor reaction of allyl radicals ...

Mercury is present in the Earth's atmosphere mainly in elemental form. The chemical transformation of mercury in the atmosphere may influence its bioaccumulation in the human food chain as well as its global cycling. We carried out the first kinetic and product studies of the reactions of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals at ...

The behaviors of free radicals produced in polyethylene irradiated with ultraviolet light and electron beams were compared in connection with primary processes of radical formation and trapping regions of free radicals. In the case of irradiation with ultraviolet light, an ESR spectrum observed at -- 196 deg C immediately ...

Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211-373 K) and ...

The decomposition and isomerization reactions of the 5-methylhex-1-yl radical (1-5MeH) have been studied at temperatures of 889-1064 K and pressures of 1.6-2.2 bar using the single pulse shock tube technique. The radical of interest was generated by shock heating dilute mixtures of 5-methylhexyl iodide to break the weak C-I bond, and the kinetics and ...

We have analysed the influence of temperature, and thus the role of radical motion on the evolution of two in-chain unsaturated bonds, transvinylene, -CH2-CH--CH-CH2- and trans-trans diene, -CH--CH-CH--CH-, created in aliphatic polymers submitted to radiations. Results reported here are related to three polymers ...

Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the alpha-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH3)OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. ...

in absolute-value mode, of propanol CH3 c CH2 b CH2 a OH (left panels) and butenol CH2 b =CHa CH2 d CH2 c OH widths of 14 and 20 kHz for propanol and butenol, respectively. (E) Columns taken parallel to the vertical t1 or w1 domain, taken along the ...

In order to improve the understanding of the low temperature combustion of ethanol, high-level ab initio calculations were performed for elementary reactions involving hydroxyethylperoxy radicals. These radicals come from the addition of hydroxethyl radicals (?CH3CHOH and ...

Mass resolved excitation spectra are presented for the benzyl radical and its clusters with Ar, N2, CH4, C2H6, and C3H8. The cluster spectra exhibit small red shifts (

E ti t d DC 8 CH O R l ti P i i. Date. DC-8 URI. DC-8 NCAR. 07/22/2004. 6%. Estimated DC-8 CH. 2. O Relative Precision. 07/31/2004 ...

The kinetics of the reactions of 1-and 2-butoxy radicals have been studied using a slow-flow photochemical reactor with GC-FID detection of reactants and products. Branching ratios between decomposition, CH3CH(O*)CH2CH3 --> CH3CHO + C2H5, reaction (7), and reaction with oxygen, ...

The potential for using alkanes-which are among the most chemically inert organic molecules-as feedstocks in chemical synthesis has stimulated a search for metal complexes capable of undergoing the C-H oxidative addition process shown in eq. (1), so that alkane chemistry more selective than that available using free radical reagents might be developed. ...

Radical Measurements Peroxy radicals were measured by the chemical amplification (PERCA) technique. The NO2 yield of the PERCA instrument used during the EASE campaigns was measured using a commercial Reactions (4) and (5), the PERCA technique effectively measures the sum of peroxy radicals. CH3O2 + NO ...

Free radicals have been detected at their steady-state concentrations in various oxygen atom-hydrocarbon flames by photoionization mass spectroscopy. The free radicals observed include CH2, CH3, C2H5, C3H3, C3H7, CHO and HCCO. From the approach of a free ...

Defines quadratic equations and explains how to solve equations involving radicals, polynomials with a degree higher than two, fractional expressions and absolute values.

... These were chosen specifically to match the species in the LIF study and ... control unit was reset with this position representing the origin (0,0,0) and ...

Measurements were made of the g values in the electron spin resonance spectra of 20 aromatic free radicals with an accuracy which has not previously been attainable. The largest source of error for both absolute and relative measurements resulted from var...

?-Carboxylate radical anions are potential reactive intermediates in the free radical oxidation of biological molecules (e.g., fatty acids, peptides and proteins). We have synthesised well-defined ?-carboxylate radical anions in the gas phase by UV laser photolysis of halogenated precursors in an ion-trap mass spectrometer. Reactions ...

The reactions of the hydroxyl radical with 2-(methylthio)ethanoic acid and 2,2[prime]-thiodiethanoic acid have been investigated in H[sub 2]O and D[sub 2]O. The initial step is a formation of an OH adduct at the sulfur moiety (absorption maximum at [lambda] = 340 nm) with absolute rate constants of k[sub OH+2[minus]MTEA] = 8.7 X 10[sup 9] M[sup [minus]1] ...

The reactions of seven metastable ionised allylic alkenyl methyl ethers of general structure, R1R2C= CHCH2OCH3+ [R1=CH3, R2=C2H5, n-C3H7, n-C6H13, or iso-C3H7; R1=C2H5, R2=n-C3H7 or iso-C3H7; R1 = n-C3H7, R2 = n-C4H9] with two different [gamma]-alkyl substituents are reported and discussed. Two common reactions are observed: loss of a molecule of methanol or elimination of an ...

During a period of 5 years, 1988 to 1992, 15 field sampling trips have been completed in an effort to continue monitoring background atmospheric concentrations of 6 man -made halocarbons, i.e., CCl_2F _2 (CFC-12), CCl_3F (CFC-11), CCl_2FCClF_2 (CFC-113), CH_3CCl _3, CCl_4, and C _2Cl_4. Approximately 70 to 90 flask air samples were collected 3 to 4 times a year from remote ...

An important chemical sink for organic peroxy radicals (RO2) in the troposphere is reaction with hydroperoxy radicals (HO2). While this reaction is typically assumed to form hydroperoxides as the major products (R1a), a small number of carbonyl-containing peroxy radicals have been shown to undergo other reactions (R1b and R1c) with ...

The reaction kinetics of chlorine atoms with a series of partially fluorinated straight-chain alcohols, CF(3)CH(2)CH(2)OH (1), CF(3)CF(2)CH(2)OH (2), CHF(2)CF(2)CH(2)OH (3), and CF(3)CHFCF(2)CH(2)OH (4), were studied in the gas phase over the temperature range of 273-363 K by using very ...

The absolute rates of reaction of tert-butoxy radicals with a variety of organic substrates in solution have been determined using laser flash photolysis techniques. The relative rates agree well with values obtained from studies of hydrocarbon halogenation by tert-butyl hypochlorite or by ESR in the case of ethers and alcohols, while the ...

An analysis of the dynamics of the radical-ion pairs of a series of 2,6,9,10-tetracyanoanthracene acceptor/alkylbenzene donor systems in acetonitrile is described in this paper. This analysis is carried out by using a combination of time-resolved emission and absorption spectroscopies and measurements of {Phi} {sub ions} from the contact radical-ion pair ...

The dissociation dynamics of methoxysulfinyl radicals generated from the photodissociation of CH(3)OS(O)Cl at 248 nm is investigated using both a crossed laser-molecular beam scattering apparatus and a velocity map imaging apparatus. There is evidence of only a single photodissociation channel of the precursor: S-Cl fission to produce Cl atoms and ...

The dissociation dynamics of methoxysulfinyl radicals generated from the photodissociation of CH3OS(O)Cl at 248 nm is investigated using both a crossed laser - molecular beam scattering apparatus and a velocity map imaging apparatus. There is evidence of only a single photodissociation channel of the precursor: S-Cl fission to produce Cl atoms and ...

Radicals such as CH{sub 2}XCH{sub 2}{sm{underscore}bullet}, where X is a halogen, play an important role in the stereochemical control observed in many chemical reactions. To elucidate the origin of the stereoselectivity, the authors calculated the structures and potential energy surfaces of the haloethyl radicals ...

This paper investigated the radical behaviour of the plasma of a mixture of methane (CH4) and decamethylcyclopentasiloxane (DMCPS) by optical emission spectroscopy. The plasma was generated by electron cyclotron resonance (ECR) discharge and was used for depositing porous SiCOH low dielectric-constant film. In the ECR discharge plasma, ...

The gas-phase radical-radical reaction dynamics of ground-state atomic oxygen [O((3)P)] with iso-propyl radicals, (CH(3))(2)CH, were investigated by applying a combination of high-resolution laser-induced fluorescence spectroscopy in a crossed-beam configuration and ab initio calculations. The nascent distributions ...

The first electron spin resonance (ESR) investigation of the CH3OH(+) cation radical is reported. Unusual methyl group deuterium effects and extensive delocalization of the unpaired electron are found. The extent of this delocalization is compared to the isoelectronic radicals CH3F(+) and ...

The rotational spectra of the two isotopic species of the bromomethyl radical, CH2 79Br and CH2 81Br, have been observed in their ground electronic state 2B1 in the 180-470 GHz frequency region, corresponding to a-type transitions from N=8-7 to N=21-20. The radical was produced by hydrogen abstraction of ...

We use a combination of crossed laser-molecular beam experiments and velocity map imaging experiments to investigate the primary photofission channels of chloroacetone at 193 nm; we also probe the dissociation dynamics of the nascent CH3C(O)CH2 radicals formed from C-Cl bond fission. In addition to the C-Cl bond fission primary ...

We use a combination of crossed laser-molecular beam experiments and velocity map imaging experiments to investigate the primary photofission channels of chloroacetone at 193 nm; we also probe the dissociation dynamics of the nascent CH(3)C(O)CH(2) radicals formed from C-Cl bond fission. In addition to the C-Cl bond fission primary ...

The kinetics and mechanism of the reactions of Cl atoms and OH radicals with CH3CH2CHO were investigated at room temperature using two complementary techniques: flash photolysis/UV absorption and continuous photolysis/FTIR smog chamber. Reaction with Cl atoms proceeds predominantly by abstraction of the aldehydic hydrogen atom to form ...

Free radicals produced by ..gamma.. irradiation at 77K in a single crystal of N-acetyl-DL-valine (CH/sub 3/)/sub 2/CHCH(NHCOCH/sub 3/)COOH were investigated by ESR spectroscopy. The aim of the experiments was to determine whether the paramagnetic centers observed at room temperature (i.e., (CH/sub 3/)/sub 2/CCH(NHCOCH/sub 3/)COOH and ...

It is proposed that the glycine precursor NH(2)CH(2)CN may be synthesised in interstellar dust clouds by the radical combination reactions NH(2)? + ?CH(2)CN ? NH(2)CH(2)CN (?G = -302 kJ mol(-1)) and/or NH(2)CH(2)? + ?CN ? NH(2)CH(2)CN (?G = -414 kJ mol(-1)). All ...

This study explored the effect of radical size, chain length, and mass on the cage recombination efficiency of photochemically generated radical cage pairs. Radical cage pairs containing long-chain radicals of the type ...

The hydrogn and methane yields from the gamma irradiation of ethanol, isopropyl alcohol, t-butyl alcohol, cyclohexanol, cyclohexane, diethyl ether, acetic acid, and ethyl acetate have been measured. These yields are deereased by the presence of benzoquinone, which is interpreted in terms of its scavenging effect for H atoms and CH/sub 3/ ...

Changes in the structure of 9-line ESR spectrum of irradiated PMMA to which the pressure of 5000 atm has been applied are studied. Thc original 9-line spectrum gradually changes so that other component spectra (i.e., singlet, doublet, and quartet) start to prevail. These spectra correspond to polyene radicals, chain radicals of the type ...

New routes to fluorinated acetylenes were developed based on additions of iodofluorocarbons to silylacetylenes. Free radical addition of, -diiodo-perfluoroalkanes to trimethylsilylacetylene gave the iodotrimethylsilylolefins, Me3SiIC=Ch(CF2)nCH=CISiMe3, w...

Photochemical processes in air parcel are drastically altered once the air parcel is in a cloud. After dissolution in a drop, CH2O immediately forms CH2(OH)2 which reacts rapidly with aqueous-phase OH radicals. This reaction is a source of formic acid in ...

Aug 8, 2006... which can be formed when a previously-discovered neutral molecule called formamide (HCONH2) combines with radicals such as CH2 and CH3, ...

... Accession Number : ADA076478. Title : Reactions of OH, CH sub 2 OH, BR sub 2, and (CNS) sub 2-Free Radicals with Cysteine at pH 5.3,. ...

The kinetics of the reactions CH3 + HBr, CD3 + HBr, CH3 + DBr, C2H5 + HBr, C2H5 + DBr, t-C4H9 + HBr,

The development of rare gas seeded fluorine atom beam source and reactions studied by this new source are main subject of this brief final report. F+CH3I to IF + CH3 reaction has been studied.