Quenching rate constants for Ne3P2) metastable atoms at room temperature

1978 ◽  
Vol 55 (1) ◽  
pp. 44-48 ◽  
Author(s):  
J.M. Brom ◽  
J.H. Kolts ◽  
D.W. Setser
Keyword(s):  
Rate Constants ◽  
Room Temperature ◽  
Quenching Rate

scholarly journals Measurements of rate constants of O2(b) quenching by CH4, NO, N2O at temperatures 300-800 K

2018 ◽  
Vol 209 ◽  
pp. 00006
Author(s):  
G.I. Tolstov ◽  
M.V. Zagidullin ◽  
N.A. Khvatov ◽  
I.A. Medvedkov ◽  
A.M. Mebel ◽  
...  
Keyword(s):  
Rate Constants ◽  
Room Temperature ◽  
Quenching Rate ◽  
Important Place ◽  
The Past ◽  
Tunable Dye Laser ◽  
Deactivation Kinetics ◽  
Electronically Excited ◽  
Excited Oxygen ◽  
Good Agreement

Electronically excited oxygen has an important place in the kinetic schemes of the processes taking place in the atmosphere, in the active medium of an oxygen-iodine laser, and in plasma-assisted combustion1. Over the past decades, a large amount of data on the rate constants of quenching O2(b) on a large number of collision partners has been accumulated. However, they mostly refer to the results of measurements at room temperature. In this paper, rate constants for the quenching of O2(b) by collisions with N2O, NO, and CH4 have been determined in the temperature range from 297 to 800 K, by the laser-induced fluorescence method. O2(b) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed via observing the temporal behavior of the b1Σg+→ X3Σg- fluorescence. From the analysis of experimental results, the following temperature dependencies of the quenching rate constants by these gases were obtained, and could be represented by the expressions: kNO=(1.77±0.2)×10-24×T3.5 exp(1138±37/T); kN2O=(2.63±0.14)×10-16×T1.5×exp(590±26/T) and kCH4=(3.54±0.4)×10-18×T1.5×exp(-220±24/T) cm3s-1. All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.

Quenching Rate Constants of NCl(a1Δ) at Room Temperature

2000 ◽  
Vol 104 (3) ◽  
pp. 539-551 ◽  
Author(s):  
Kevin B. Hewett ◽  
G. C. Manke ◽  
D. W. Setser ◽  
G. Brewood
Keyword(s):  
Rate Constants ◽  
Room Temperature ◽  
Quenching Rate

Fluorescence Quenching of Aminodiphenylamines with Chloromethanes

2002 ◽  
Vol 67 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Nachiappan Radha ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Ground State ◽  
Rate Constants ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
Charge Transfer Interaction ◽  
Electronically Excited ◽  
A Charge

The fluorescence quenching of 2-aminodiphenylamine (2ADPA), 4-aminodiphenylamine (4ADPA) and 4,4'-diaminodiphenylamine (DADPA) with tetrachloromethane, chloroform and dichloromethane have been studied in hexane, dioxane, acetonitrile and methanol as solvents. The quenching rate constants for the process have also been obtained by measuring the lifetimes of the fluorophores. The quenching was found to be dynamic in all cases. For 2ADPA and 4ADPA, the quenching rate constants of CCl4 and CHCl3 depend on the viscosity, whereas in the case of CH2Cl2, kq depends on polarity. The quenching rate constants for DADPA with CCl4 are viscosity-dependent but the quenching with CHCl3 and CH2Cl2 depends on the polarity of the solvents. From the results, the quenching mechanism is explained by the formation of a non-emissive complex involving a charge-transfer interaction between the electronically excited fluorophores and ground-state chloromethanes.

Quenching rate constants for reactions of Ar(4p′[1/2]0, 4p[1/2]0, 4p[3/2]2, and 4p[5/2]2) atoms with 22 reagent gases

2001 ◽  
Vol 115 (7) ◽  
pp. 3144-3154 ◽  
Author(s):  
N. Sadeghi ◽  
D. W. Setser ◽  
A. Francis ◽  
U. Czarnetzki ◽  
H. F. Döbele
Keyword(s):  
Rate Constants ◽  
Quenching Rate

An experimental study of the reactivity of the hydroxide anion in the gas phase at room temperature, and its perturbation by hydration

1981 ◽  
Vol 59 (11) ◽  
pp. 1615-1621 ◽  
Author(s):  
Scott D. Tanner ◽  
Gervase I. Mackay ◽  
Diethard K. Bohme
Keyword(s):  
Experimental Study ◽  
Proton Transfer ◽  
Gas Phase ◽  
Rate Constants ◽  
Room Temperature ◽  
Gas Phase Reactions ◽  
Flowing Afterglow ◽  
Hydroxide Anion

Flowing afterglow measurements are reported which provide rate constants and product identifications at 298 ± 2 K for the gas-phase reactions of OH− with CH3OH, C2H5OH, CH3OCH3, CH2O, CH3CHO, CH3COCH3, CH2CO, HCOOH, HCOOCH3, CH2=C=CH2, CH3—C≡CH, and C6H5CH3. The main channels observed were proton transfer and solvation of the OH−. Hydration with one molecule of H2O was observed either to reduce the rate slightly and lead to products which are the hydrated analogues of the "nude" reaction, or to stop the reaction completely, k ≤ 10−12 cm3 molecule−1 s−1. The reaction of OH−•H2O with CH3—C≡CH showed an uncertain intermediate behaviour.

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.

REACTION OF OXYGEN ATOMS WITH BUTADIENE

1960 ◽  
Vol 38 (11) ◽  
pp. 2187-2195 ◽  
Author(s):  
R. J. Cvetanović ◽  
L. C. Doyle
Keyword(s):  
Pressure Dependence ◽  
Rate Constants ◽  
Room Temperature ◽  
Relative Rate ◽  
Excess Energy ◽  
General Mechanism ◽  
Arrhenius Parameters ◽  
Heats Of Reaction ◽  
Relative Rate Constants ◽  
Oxygen Atoms

Reaction of oxygen atoms with 1,3-butadiene has been investigated at room temperature. It is found that it conforms to the general mechanism established previously for the analogous reactions of monoolefins. Only 1,2-addition occurs, and the addition products, butadiene monoxide and 3-butenal, possess excess energy when formed as a result of high heats of reaction. The pressure dependence of the formation of the addition products yields the values of the "lifetimes" of the initially produced "hot" molecules. The relative rate constants have been determined at 25 and 127 °C and from these the relative values of the Arrhenius parameters have been calculated.

COMBINATION AND DISPROPORTIONATION OF ETHYL RADICALS: INFLUENCE OF THE REACTION H+C2H5 = C2H6

1955 ◽  
Vol 33 (5) ◽  
pp. 821-829 ◽  
Author(s):  
Moyra J. Smith ◽  
Patricia M. Beatty ◽  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Light Intensity ◽  
Excellent Agreement ◽  
Mercury Concentration ◽  
Rate Constants ◽  
Room Temperature ◽  
Low Light ◽  
Ethylene Concentration ◽  
Light Intensities ◽  
Ethyl Radicals ◽  
Hydrogenation Of Ethylene

The mercury (3P1) photosensitized hydrogenation of ethylene has been studied at room temperature as a function of ethylene concentration, mercury concentration, and light intensity. In addition to combination and disproportionation, ethyl radicals have been shown to take part in the reaction[Formula: see text]The conditions favoring this reaction have been established and anomalous values previously found for the ratio of ethane to butane have been explained. The value obtained for the ratio of the rate constants for the disproportionation and combination of ethyl radicals, 0.15 ±.01, is in excellent agreement with the values obtained by other methods. Hexane formation is of some importance at low light intensities and high ethylene concentrations, and is adequately accounted for by the reactions[Formula: see text]

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