Quenching of the O2 (Aν=2 → Xν=5) Herzberg I band by O2(a) and O

1984 ◽  
Vol 62 (12) ◽  
pp. 1599-1602 ◽  
Author(s):  
R. D. Kenner ◽  
E. A. Ogryzlo
Keyword(s):  
Rate Constant ◽  
Electrical Discharge ◽  
Flow System ◽  
Nickel Surface ◽  
Quenching Rate ◽  
Vibrational Levels ◽  
Fast Flow ◽  
Oxygen Atoms

Data are presented that indicate that O2(a1Δg) is an effective quencher of [Formula: see text]. In a system where O and O2 are produced by an electrical discharge in a fast-flow system, O2(A) molecules were formed by allowing some of the oxygen atoms to recombine on a nickel surface. From the decay of O2(A) in the presence of O2(a), a rate constant of (8.1 ± 3) × 10−11 cm3 molec−1 s−1 was obtained for the interaction of these two species. A revised value of 1.3 × 10−11 cm3 molec−1 s−1 for the rate constant for the O2(A)ν = 2 quenching by O has been determined. The relative quenching rate of vibrational levels 0–4 have also been estimated.

THE REACTION OF NITROGEN ATOMS WITH OXYGEN ATOMS IN THE ABSENCE OF OXYGEN MOLECULES

1961 ◽  
Vol 39 (8) ◽  
pp. 1601-1607 ◽  
Author(s):  
C. Mavroyannis ◽  
C. A. Winkler
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Atom ◽  
Rate Constant ◽  
Rate Constants ◽  
Flow System ◽  
Titration Method ◽  
Active Nitrogen ◽  
Reaction Tube ◽  
Fast Flow ◽  
Oxygen Atoms

The reaction has been studied in a fast-flow system by introducing nitric oxide in the gas stream with excess active nitrogen. The nitrogen atom consumption was determined by titrating active nitrogen with nitric oxide at different positions along the reaction tube. The rate constant is found to be k1 = 1.83(± 0.2) × 1015 cc2 mole−2 sec−1 at pressures of 3, 3.5, and 4 mm, and with an unheated reaction tube.The homogeneous and surface decay of nitrogen atoms involved in the above system were studied using the nitric oxide titration method, and the rate constants were found to be k3 = 1.04 ± 0.17 × 1016 cc2 mole−2 sec−1, and k4 = 2.5 ± 0.2 sec−1 (γ = 7.5 ± 0.6 × 10–5), respectively, over the range of pressures from 0.5 to 4 mm with an unheated reaction tube.

The Rate of Recombination of H Atoms in the Presence of NH3

1973 ◽  
Vol 51 (22) ◽  
pp. 3771-3773 ◽  
Author(s):  
L. Teng ◽  
C. A. Winkler
Keyword(s):  
Rate Constant ◽  
Pressure Range ◽  
Flow System ◽  
Carrier Gas ◽  
A Value ◽  
Fast Flow

The rate constant for the homogeneous recombination of H atoms in the presence of NH3, with He as carrier gas, has been determined at 298°K in a fast flow system, over the pressure range 1.50 to 4.55 Torr, using e.s.r. technique. A value of either 4.00 × 1016 or 5.14 × 1016 cm6 mol−2 s−1 was calculated, depending upon the rate constant taken, or estimated, from the literature for the recombination in the presence of helium.

Vibrational energy distribution in HF formed by elimination from activated CH3CF3 and CH2CF2

1970 ◽  
Vol 48 (18) ◽  
pp. 2919-2930 ◽  
Author(s):  
P. N. Clough ◽  
J. C. Polanyi ◽  
R. T. Taguchi
Keyword(s):  
Rate Constants ◽  
Vibrational Energy ◽  
Flow System ◽  
Relative Rate ◽  
Elimination Reaction ◽  
Vibrationally Excited ◽  
Vibrational Levels ◽  
Relative Rate Constants ◽  
Fast Flow ◽  
Vibrational Energy Distribution

The combination–elimination reaction CH3 + CF3 → CH3CF3† → CH2CF2 + HF has been studied in a fast-flow system. Infrared chemiluminescence arising from the HF product has been observed from vibrational levels v = 1–4, and relative rate constants, k(v), have been obtained for HF formation in these levels. A study has also been made of the reaction CH2CF2 + Hg*(63P1) → CHCF + HF + Hg(61S0), which has been found to produce vibrationally-excited HF. Relative rate constants k(v) for vibrational levels v = 1–4 have been obtained. It appears that channelling of the potential energy into HF vibration, in the course of the elimination step, is more efficient in the first than in the second of these reactions. In the second reaction HF is eliminated with considerable rotational excitation.

Rates of elementary processes in the chain reaction between hydrogen and oxygen I. Reactions of oxygen atoms

1963 ◽  
Vol 275 (1363) ◽  
pp. 544-558 ◽  
Keyword(s):  
Rate Constant ◽  
Atomic Oxygen ◽  
Elevated Temperatures ◽  
Collision Frequency ◽  
Flow System ◽  
Chain Reaction ◽  
Elementary Processes ◽  
A Value ◽  
Good Agreement ◽  
Oxygen Atoms

The rates of reaction of 3 P oxygen atoms with hydroxyl and hydrogen have been measured in a flow system at pressures around 2 mmHg. The former reaction, O + OH -> H + O 2 , ( — 4) occurred in the products of the rapid reaction between H and NO 2 , and was followed by measurements of atomic oxygen concentrations. k -4 was found to be 5±2 x 10 -11 cm 3 molecule -1 s -1 at 265 and 293 °K. This result, when combined with data on the reverse reaction at elevated temperatures, gives a value of k -4 which is virtually independent of temperature and equal to about 1/20 of the bimolecular collision frequency. The reaction O + H 2 -> OH + H (3) was studied in the absence of molecular oxygen and found to have a rate constant of 6 x 10 -13 exp (-8900/ RT ) cm 3 molecule -1 s -1 in the range 409 to 733 °K. This is in good agreement with values obtained at higher temperatures. The rate constant for O + D 2 was significantly less than that for O + H 2 at temperatures between 491 and 671 °K.

Mechanistic studies of aromatic ketone-sensitized photoreduction of bis(acetylacetonato)copper(II)

1983 ◽  
Vol 61 (5) ◽  
pp. 801-808 ◽  
Author(s):  
Yuan L. Chow ◽  
Gonzalo E. Buono-Core ◽  
Bronislaw Marciniak ◽  
Carol Beddard
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Decay Rates ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Aromatic Ketone ◽  
Quantum Yields ◽  
Triplet States ◽  
Quenching Rate ◽  
Triplet Energy

Bis(acetylacetonato)copper(II), Cu(acac)2, quenches triplet excited states of ketones and polynuclear aromatic hydrocarbons efficiently, but only aromatic ketones with high triplet energy successfully sensitize photoreduction of Cu(acac)2 in alcohols under nitrogen to give derivatives of aeetylacetonatocopper(I), Cu(acac). For the triplet state benzophenone-sensitized photoreduction of Cu(acac)2, the quantum yields of photoreduction (ΦC) and those of benzophenone disappearance (ΦB) were determined in methanol with various concentrations of Cu(acac)2. The values of the quenching rate constant, kq, determined from these two types of monitors on the basis of the proposed mechanism were in good agreement (6.89 ~ 7.35 × 109 M−1 s−1). This value was higher, by a factor of about two, than that obtained from the monitor of the benzophenone triplet decay rates generated by flash photolysis in the presence of Cu(acac)2. The quenching rate constants of various aromatic ketone and hydrocarbon triplet states by Cu(acac)2 were determined by flash photolysis to be in the order of the diffusion rate constant and the quantum yields of these photoreductions were found to be far from unity. Paramagnetic quenching, with contributions of electron exchange and charge transfer, was proposed as a possible quenching mechanism. For a series of aromatic ketone sensitizers with higher triplet energy, this mechanism was used to rationalize the observed high quenching rate constants in contrast to the low quantum yields of photoreduction.

Temperature dependence of the O+I(P21/2)→O+I(P23/2) quenching rate constant

2009 ◽  
Vol 105 (9) ◽  
pp. 094911 ◽  
Author(s):  
Pavel A. Mikheyev ◽  
David J. Postell ◽  
Michael C. Heaven
Keyword(s):  
Temperature Dependence ◽  
Rate Constant ◽  
Quenching Rate ◽  
Quenching Rate Constant

The lifetime of hydrogen adsorbed on a slightly oxidized nickel surface

1957 ◽  
Vol 240 (1222) ◽  
pp. 423-436 ◽  
Keyword(s):  
Oxide Film ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Molecular Beam ◽  
Copper Surface ◽  
Solid Surfaces ◽  
Nickel Surface ◽  
Order Process ◽  
Adsorbed Molecules ◽  
First Order

A method for investigating the lifetimes of adsorbed molecules on solid surfaces is described. A molecular beam of hydrogen was projected on to the surface of a spinning nickel disk, and the hydrogen evaporating from the surface at different times after deposition was collected and measured with a mass spectrometer. On a slightly oxidized nickel surface all the hydrogen was adsorbed. The subsequent evaporation was a first-order process with a rate constant of 4·5 x 10 11 exp ( -11·5 kcal/ RT ) S -1 . With a mixed molecular beam of hydrogen and deuterium no exchange was produced by the adsorption, which is considered to be molecular. Attempts to remove the oxide film from the nickel surface gave an un­stable surface on which no clear results were obtained. The lifetime of hydrogen on a copper surface was too short to measure.

Mechanism and rate constant of the reaction of oxygen atoms with acetylene

1965 ◽  
Vol 14 (3) ◽  
pp. 396-399 ◽  
Author(s):  
L. I. Avramenko ◽  
R. V. Kolesnikova ◽  
G. I. Savinova
Keyword(s):  
Rate Constant ◽  
Oxygen Atoms

The recombination of oxygen atoms in a discharge flow system

1964 ◽  
Vol 41 (8) ◽  
pp. 429 ◽  
Author(s):  
B. A. Thrush
Keyword(s):  
Flow System ◽  
Discharge Flow ◽  
Oxygen Atoms

Quenching rate constant for O(1S)+NO

1972 ◽  
Vol 1 (4) ◽  
pp. 341-344 ◽  
Author(s):  
R. Atkinson ◽  
K.H. Welge
Keyword(s):  
Rate Constant ◽  
Quenching Rate ◽  
Quenching Rate Constant
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