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.

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.

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).

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 .

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.

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.

Absorption spectrum of the H2S molecule in the vacuum ultraviolet region

1979 ◽  
Vol 57 (5) ◽  
pp. 745-760 ◽  
Author(s):  
Harunobu Masuko ◽  
Yumio Morioka ◽  
Masatoshi Nakamura ◽  
Eiji Ishiguro ◽  
Michio Sasanuma
Keyword(s):  
Absorption Spectrum ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Broad Band ◽  
Ultraviolet Region ◽  
Coupling Scheme ◽  
Rydberg Series ◽  
Vibrationally Excited ◽  
Electron Synchrotron ◽  
Orbital Character

The optical absorption spectrum of the H2S molecule in the region from 2050 to 1150 Å has been studied by a photographic method, using the radiation from a 1.3-GeV electron synchrotron as a background source. Numerous bands including those due to dipole forbidden transitions are observed in the spectrum. Five types of Rydberg series are assigned to electronic transitions from the outermost 2b1 orbital to the d-like orbitals, three types to the p-like orbitals, and one type to the s-like orbital. The quantum defects of these transitions and a series limit of 84 417 ± 8 cm−1 (10.466 ± 0.001 eV) were determined using the extended Rydberg series. The first member of the A Rydberg series splits into four bands, which is discussed with jj coupling scheme. The upper state of the 2000-Å (6.20-eV) broad band is assigned to the (2b1)−1 (6a1/4sa1) 1B1 state which is predominantly of valence orbital character. Transitions to vibrationally excited state were also investigated and the limit to which the (100) vibrationally excited Rydberg series converges was determined to be 86 882 ± 20 cm−1 (10.772 ± 0.003 eV). The results obtained in this experiment are compared with theoretical calculations.

The flash photolysis of ozone

1957 ◽  
Vol 242 (1230) ◽  
pp. 265-276 ◽  
Keyword(s):  
Electronic State ◽  
Vibrational Energy ◽  
Inert Gases ◽  
Inert Gas ◽  
Ground Electronic State ◽  
Explosive Decomposition ◽  
Kcal Mole ◽  
Vibrationally Excited ◽  
Energy Chain ◽  
Excited Oxygen

The photolytic decomposition of ozone in ultra-violet radiation has been studied by kinetic spectroscopy. It has been shown that vibrationally excited oxygen in its ground electronic state plays a most important part in the decomposition. These molecules have sufficient vibrational energy to bring about dissociation of ozone, thus regenerating oxygen atoms which can again produce vibrationally excited oxygen. The importance of this energy chain is emphasized by comparative studies on the explosive decomposition of pure ozone, and the isothermal decomposition when an excess of inert gas is present. In the former case the O* 2 is removed so rapidly, mainly by reaction with ozone, that no absorption due to it can be detected. Using an excess of inert gas to obtain isothermal conditions it has been possible to observe Schumann–Runge absorption of oxygen molecules in their ground electronic state, with up to 16 quanta of vibrational energy. The vibrational energy distribution of the oxygen molecules formed has an apparent maximum at v " = 13 (53.5 kcal/mole) and falls off sharply at v " = 12 and 16 (49.0 and 63.2 kcal/mole). It is shown that the only reasonable reaction for the production of excited oxygen is O + O 3 → O* 2 + O 2 . Studies on the rate of ozone decay with time have also been carried out and the results analyzed in terms of the rate constants of reactions involving the deactivation of excited oxygen and the three-body recombination O + O 2 + M → O 3 + M . It is shown that the spherically symmetrical and chemically inert gases such as A, He and SF 6 are much less efficient in bringing about recombination than N 2 , N 2 O or CO 2 .

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.

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