Energy disequilibrium in the flash photolysis of NO 2

1973 ◽  
Vol 334 (1599) ◽  
pp. 553-568 ◽  
Keyword(s):  
Nitric Oxide ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Dissociation Limit ◽  
Primary Process ◽  
Transfer Energy ◽  
Vibrationally Excited ◽  
Absolute Concentrations ◽  
The Absolute ◽  
Excited Oxygen

From measurements of the absolute concentrations of vibrationally excited oxygen produced in levels v" = 4 to v" = 13, it is concluded that ca . 20 % of the exothermicity of the reaction O( 3 P) + NO 2 → NO + O + 2 ( v" ≤11) (1) appears initially as vibrational energy in oxygen. Vibrationally excited nitric oxide ( v" = 1, 2) is also observed and may be produced in this reaction or in the primary process NO 2 + hv → NO ( v" ≤ 2) + O( 3 P). More highly excited oxygen ( v" ≤ 15), with energy exceeding the exothermicity of the reaction, is produced in reaction (1) when the NO 2 is first excited by radiation above the dissociation limit near 400 nm. The excited NO 2 thus produced can also transfer energy to nitric oxide. NO 2 * + NO( v" = 0) → NO 2 + NO( v" = 1).

VIBRATIONAL DISEQUILIBRIUM IN REACTIONS BETWEEN ATOMS AND MOLECULES

1960 ◽  
Vol 38 (10) ◽  
pp. 1769-1779 ◽  
Author(s):  
N. Basco ◽  
R. G. W. Norrish
Keyword(s):  
Hydroxyl Radicals ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Electronic Energy ◽  
Reaction Products ◽  
Energy Distributions ◽  
Vibrationally Excited ◽  
Atoms And Molecules ◽  
New Class ◽  
Excited Oxygen

Observations on the production of vibrationally excited oxygen molecules in the flash photolysis of nitrogen peroxide and of ozone have extended previous work on these systems. In the case of nitrogen peroxide it has been shown that oxygen molecules possessing the entire exothermicity of the reaction in the form of vibrational energy are produced. A new class of reactions is reported in which vibrationally excited hydroxyl radicals are produced under isothermal conditions by the reaction O(1D) + RH → OH* + R, in which the energy for excitation is contributed by the electronic energy of the oxygen atom.These and other cases of non-equilibrated energy distributions in reaction products and theories accounting for this phenomenon are reviewed.

The study of energy transfer by kinetic spectroscopy I. The production of vibrationally excited oxygen

1956 ◽  
Vol 233 (1195) ◽  
pp. 455-464 ◽  
Keyword(s):  
Flash Photolysis ◽  
Vibrational Energy ◽  
Vibrationally Excited ◽  
Near Resonance ◽  
Vibrational Levels ◽  
Great Excess ◽  
First Time ◽  
Kinetics Of ◽  
Excited Oxygen ◽  
Electronic Ground

The flash photolysis of chlorine dioxide or of nitrogen dioxide in a great excess of inert gasyields oxygen molecules in their electronic ground states with up to eight quanta of vibrational energy. By a study of the reaction kinetics of the two systems, it is concluded that these excited molecules have their origin in the reactions O + NO 2 = NO + O 2 and O + CIO 2 = CIO + O 2 respectively. Thus, for the first time we have available a very convenient method of studying the collisional transfer and degradation of vibrational energy from molecules in the higher vibrational levels of the ground state and some preliminary measurements of the efficiency of deactivation by various molecules are given. It is concluded that the energy is removed most readily either when there is near resonance of the vibrational levels with those of the oxygen, or by free radicals. Some of the reactions of the chlorine oxides present are also discussed.

Vibrationally excited nitric oxide produced in the flash photolysis of nitrosyl halides

1962 ◽  
Vol 268 (1334) ◽  
pp. 291-303 ◽  
Keyword(s):  
Nitric Oxide ◽  
Energy Transfer ◽  
Ground State ◽  
Vibrational Relaxation ◽  
Direct Evidence ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Electronic States ◽  
Vibrationally Excited ◽  
Direct Production

The flash photolysis of nitrosyl chloride and nitrosyl bromide has been studied under isothermal conditions. Vibrationally excited nitric oxide molecules were produced and all levels from v " = 0 to v " = 11 were observed in absorption from the ground electronic states in the β, γ, δ and Є systems. Some of these bands have not previously been reported. The mechanism of the production is either directly NO R + hv → NO ( X 2 II , v ≤ 11) + R ( 2 P ), or by the sequence which includes the reactions NO R + hv → NO( 4 II ) + R , NO. 4 II + M → NO ( X 2 II , v > 0) + M In the latter case, the 4 II state of NO lies not more than 3·5 eV above the ground state. Other possible mechanisms and models accounting for the direct production of vibrationally excited NO in its ground electronic states are discussed. By flashing chlorine in the presence of NOCl it was shown that the reaction Cl + NOCl → Cl 2 + NO ( v > 0) does not occur, thus providing direct evidence that in reactions of the type A + BCD → AB + CD only the AB molecule containing the newly formed bond can be vibrationally excited. Vibrational relaxation is very rapid and probably occurs by step-wise degradation involving resonance vibrational energy transfer. NOCl and NOBr are very efficient and with NO itself the reaction NO ( v = n ) + NO ( v = 0) → NO ( v = n -1) + NO ( v = 1) can be followed.

Studies of the reactions of excited oxygen atoms and molecules produced in the flash photolysis of ozone

1960 ◽  
Vol 254 (1278) ◽  
pp. 317-326 ◽  
Keyword(s):  
Flash Photolysis ◽  
Vibrational Energy ◽  
Oh Radicals ◽  
Chain Reaction ◽  
Vibrationally Excited ◽  
Detailed Mechanism ◽  
Photolytic Decomposition ◽  
Excited Oxygen ◽  
Electronic Ground ◽  
Oxygen Atoms

The photolytic decomposition of ozone has been further investigated using the technique of flash photolysis. Earlier results have been extended and a detailed mechanism for the production of vibrationally excited oxygen molecules put forward. Comparative studies of the decomposition with and without traces of water present have shown that the 1 D oxygen atom must be responsible for the chain reaction in both cases. When dry ozone is photolyzed under isothermal conditions, absorption due to vibrationally excited oxygen molecules in their electronic ground states is detected. These molecules are produced by the reaction O + O 3 → O* 2 + O 2 with up to 17 quanta of vibrational energy, and are rotationally cold. When water is present, however, no absorption due to O* 2 occurs but strong OH absorption is seen and it is shown that OH radicals are responsible for propagating the chain reaction in this case. These radicals can only be formed by the reaction O( 1 D ) + H 2 O → 2OH + O 2 , leading to chain branching. It is an interesting observation that this reaction must be preferred to that with ozone stated above. This conclusion will be examined later. Reactions of 1 D oxygen atoms with fluorine, chlorine, bromine and hydrogen have also been investigated.

Reactions of halogen oxides studied by flash photolysis IV. Vacuum ultraviolet kinetic spectroscopy studies on chlorine dioxide

1974 ◽  
Vol 336 (1607) ◽  
pp. 495-505 ◽  
Keyword(s):  
Vacuum Ultraviolet ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Heat Of Reaction ◽  
Rydberg Series ◽  
Vibrationally Excited ◽  
Extinction Coefficients ◽  
Spectroscopy Studies ◽  
Halogen Oxides ◽  
Excited Oxygen

The rate constants for the production of vibrationally excited oxygen in the reactions O + CIO 2 -----» O 2 (v''≤ 15) + CIO O + CIO -----» O 2 (v''≤ 14) + Cl are approximately equal for all values of v" ≤ 13. The oxygen initially receives 45+10% of the heat of reaction in the form of vibrational energy. Extinction coefficients have been measured for several bands of the C-X, D -X and E -X systems of CIO 2 in the vacuum ultraviolet. Five new systems are reported between 141 and 128 nm. Two of these, F-X and J-X , and the C-X system form a Rydberg series for an ionization potential of 10.36 eV.

The reaction of cyanogen radicals with nitric oxide

1965 ◽  
Vol 283 (1394) ◽  
pp. 291-301 ◽  
Keyword(s):  
Nitric Oxide ◽  
Chemical Reaction ◽  
Vibrational Energy ◽  
Vibrational Excitation ◽  
Resonance Energy ◽  
Ultra Violet ◽  
Vibrationally Excited ◽  
Near Resonance ◽  
Continuous Absorption ◽  
Unstable Compound

Vibrational energy transfer and a chemical reaction between nitric oxide and the cyanogen radical have been studied by flash photolysing cyanogen and cyanogen bromide in the presence of nitric oxide. The product of the chemical reaction is, at least in part, the unstable compound nitrosyl cyanide NOCN and the rate constant is 2 x 10 12 ml. mole -1 s -1 or 1 x 10 17 ml. mole -2 s -1 with nitrogen as third body. The compound has a continuous absorption in the ultra-violet and yields vibrationally excited nitric oxide on photolysis. Vibrationally excited cyanogen radicals produced by means of electronic excitation of the radical produce vibrational excitation of the nitric oxide through near resonance energy exchange. Vibrational equilibrium is reached by nitric oxide through further resonance exchanges: CN + NO → NOCN, NOCN + hv → N O ( v > 0) + CN, NO ( v = 0) + CN ( v = n ) → NO ( v = 1) + CN ( v = n – 1 ) , NO ( v = 1) + CN ( v = m ) → NO ( v = 2) + CN ( v = m –1 ), 2NO { v = 1) ⇌ NO ( v = 2) + NO ( v = 0), NO ( v = 2) +NO ( v = 1) ⇌ NO ( v = 3) + NO { v = 0), etc.

Distribution and Relaxation of Vibrationally Excited Oxygen in Flash Photolysis of Ozone

1964 ◽  
Vol 40 (2) ◽  
pp. 451-458 ◽  
Author(s):  
Robert V. Fitzsimmons ◽  
Edward J. Bair
Keyword(s):  
Flash Photolysis ◽  
Vibrationally Excited ◽  
Excited Oxygen

Reactions of halogen oxides studied by flash photolysis II. The flash photolysis of chlorine monoxide and of the ClO free radical

1971 ◽  
Vol 323 (1554) ◽  
pp. 401-415 ◽  
Keyword(s):  
Free Radical ◽  
Quantum Yield ◽  
Rate Constant ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Vibrationally Excited ◽  
Chlorine Atoms ◽  
Chlorine Monoxide ◽  
Halogen Oxides ◽  
Excited Oxygen

A study of the flash photolysis of chlorine monoxide and of its photosensitized decomposition by chlorine and bromine has yielded rate constants for the reactions Cl + Cl 2 O → Cl 2 + ClO, k 1 = 4.1 x 10 8 l mol -1 s -1 , Br + Cl 2 O → BrCl + ClO, k 9 = 6.1 x 10 8 l mol -1 s -1 , ClO + Cl 2 O → ClO 2 + Cl 2 , k 3 = 2.6 x 10 5 l mol -1 s -1 , ClO + Cl 2 O → Cl 2 + O 2 + Cl, k 4 = 6.5 x 10 5 l mol -1 s -1 , 2ClO → Cl 2 + O 2 , k 2 = 2.8 x 10 7 l mol -1 s -1 . The quantum yield for the decomposition of chlorine monoxide was measured in each of the three systems and is quantitatively accounted for by the reactions given. The CIO free radical has been flash photolysed and the production of vibrationally excited oxygen in the reaction O + CIO → Cl + O* 2 ( v" ≼ 14), k 11 = 7.5 x 10 9 l mol -1 s -1 demonstrated. The same reaction is responsible for the production of O* 2 in the flash photo­lysis of Cl 2 O with radiation below ~ 300 nm. The relaxation of O* 2 by chlorine atoms is exceptionally efficient, with a rate constant for v" = 12 in excess of 2 x 10 9 l mol -1 s -1 . The corresponding rate constant for relaxation by Cl 2 O is < 10 8 l mol -1 s -1 .

Vibrationally Excited Nitric Oxide Produced in the Flash Photolysis of Nitrosyl Chloride

Nature ◽  
1961 ◽  
Vol 189 (4763) ◽  
pp. 455-456 ◽  
Author(s):  
N. BASCO ◽  
R. G. W. NORRISH
Keyword(s):  
Nitric Oxide ◽  
Flash Photolysis ◽  
Nitrosyl Chloride ◽  
Vibrationally Excited

Reactions of halogen oxides studied by flash photolysis. I. The flash photolysis of chlorine dioxide

1971 ◽  
Vol 323 (1552) ◽  
pp. 29-68 ◽  
Keyword(s):  
Chlorine Dioxide ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Vibrationally Excited ◽  
Extinction Coefficients ◽  
Chlorine Monoxide ◽  
Vibrational Levels ◽  
Halogen Oxides ◽  
Excited Oxygen

The production and decay of the CIO radical and of vibrationally excited oxygen following the isothermal flash photolysis of chlorine dioxide has been studied. From their dependence on flash energy and from the effects of added chlorine, oxygen and chlorine monoxide on the system, the following mechanism and rate constants are proposed: CIO 2 + hv → CIO + O 2CIO → CI 2 + O 2 K 1 = 2.7 x 10 7 l mol -1 s -1 O + CIO 2 → CIO + O 2 * ( v " ≼ 15) k 3 = 3.0 x 10 10 l mol -1 s -1 O + CIO → CI + O 2 * ( v " ≼ 14) k 4 = 7.0 x 10 9 l mol -1 s -1 CIO (CIO 2 ) + O 2 * ( v " = n ) → CIO (CIO 2 ) + O 2 * ( v " < n ) k 10 ( v " = 12) = 2 x 10 8 l mol -1 s -1 CI + O 2 * ( v " = n ) → CI + O 2 * ( v " < n ) k 11 ( v " = 12) = 7 x 10 9 l mol -1 s -1 O + O 2 * ( v " = n ) → O + O 2 * ( v " < n ) k 12 ( v " = 12) = 2 x 10 10 l mol -1 s -1 O + Cl 2 O → 2CIO k 6 = 5.2 x 10 9 l mol -1 s -1 The rate constants k 10 , k 11 and k 12 for O 2 * (v" = 6) and the relative values of k 3 for various vibrational levels have also been measured. Studies of the flash photolysis of mixtures of chlo­rine monoxide and chlorine dioxide and of chlorine and oxygen have yielded values of k 1 in agreement with that given above. The extinction coefficients of the CIO radical at 257.7, 277.2 and 292 nm were found to be 1150, 1700 and 1050 l mol -1 cm -1 respectively.

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