Gas phase Boudouard reactions involving singlet–singlet and singlet–triplet CO vibrationally excited states: implications for the non-equilibrium vibrational kinetics of CO/CO2 plasmas

This study of near-resonant, vibration–vibration (V–V) gas-phase energy transfer in diatomic molecules uses the theoretical/computational method, of Marsh & McCaffery (Marsh & McCaffery 2002 J. Chem. Phys. 117 , 503 ( doi:10.1063/1.1489998 )) The method uses the angular momentum (AM) theoretical formalism to compute quantum-state populations within the component molecules of large, non-equilibrium, gas mixtures as the component species proceed to equilibration. Computed quantum-state populations are displayed in a number of formats that reveal the detailed mechanism of the near-resonant V–V process. Further, the evolution of quantum-state populations, for each species present, may be followed as the number of collision cycles increases, displaying the kinetics of evolution for each quantum state of the ensemble's molecules. These features are illustrated for ensembles containing vibrationally excited N 2 in H 2 , O 2 and N 2 initially in their ground states. This article is part of the theme issue ‘Modern theoretical chemistry’.

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Gas phase photolysis of 1-pentene and 1-pentene-d10 at 7.1 and 7.6 eV. Kinetic considerations

Canadian Journal of Chemistry ◽

10.1139/v78-235 ◽

1978 ◽

Vol 56 (10) ◽

pp. 1435-1441 ◽

Cited By ~ 6

Author(s):

Andrzej Więckowski ◽

Guy J. Collin

Keyword(s):

Gas Phase ◽

Isotope Effects ◽

Distribution Functions ◽

Static System ◽

Hydrogen Atoms ◽

Photochemical Process ◽

Radical Decomposition ◽

Energy Distribution Functions ◽

Kinetics Of ◽

Non Equilibrium

The gas phase photolysis of n-pentene was carried out in a static system using nitrogen resonance lines at [Formula: see text] and the bromine line at [Formula: see text] The mechanism for the photolysis was proposed and compared to what was concluded at 8.4 eV (147 nm, the xenon resonance line). The kinetics of the decomposition of the excited C3H5* radicals formed in the primary photochemical process and the C5H11* radicals formed by the addition of hydrogen atoms to the parent molecules were discussed. The investigations were extended to the n-C5D10 photolytic System. The observed decomposition rate constants of the excited pentyl radicals as well as the secondary non-equilibrium isotope effects agree with the data published earlier. It is concluded from these experiments that, at least at 7.6 eV, hot hydrogen atoms are produced.Only a small fraction of the C3H5* radicals décompose and yield aliène. At the same time the combined primary–secondary non-equilibrium isotope effects are much less than those calculated for the 'pure' primary isotope effects. To account for these observations, it is assumed that the C3H5* radicals are formed with a wide spread in the internal energies. Since the threshold of the decomposition of the excited C3H5* radical lies above its mean excess energy (calculated on the statistical basis), an analogy in the energy-distribution functions on the radicals activated photochemically and thermally may be suggested. If so, an inverse secondary isotope effect may contribute to the gross effect involved in the C3H5* radical decomposition.

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Emission and Deactivation of the Excited States of 2,3-Pentanedione

Canadian Journal of Chemistry ◽

10.1139/v72-210 ◽

1972 ◽

Vol 50 (9) ◽

pp. 1338-1344 ◽

Cited By ~ 2

Author(s):

A. W. Jackson ◽

A. J. Yarwood

Keyword(s):

Triplet State ◽

Gas Phase ◽

Excited States ◽

Singlet State ◽

Triplet States ◽

Excited Singlet ◽

Vibrationally Excited ◽

Singlet Level ◽

Singlet And Triplet States ◽

Fluorescence And Phosphorescence

Vibrationally excited singlet and triplet states of 2,3-pentanedione are formed by photolysis at 365 nm. The processes removing these excited states in the gas phase are studied by measuring the fluorescence and phosphorescence yields. Fluorescence can occur from the vibrationally excited, as well as the vibrationally equilibrated, singlet state. The fluorescence and phosphorescence data are considered in terms of mechanisms which involve either weak or strong collisions. Although the data cannot distinguish between the alternatives, there are two significant conclusions. The fluorescence data require that emission occur from at least two levels in the singlet manifold. To explain the phosphorescence data, the highest emitting singlet level must not lead to a vibrationally equilibrated triplet state.

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Vibrational kinetics of electronically excited states in H2 discharges

The European Physical Journal D ◽

10.1140/epjd/e2017-80080-3 ◽

2017 ◽

Vol 71 (11) ◽

Cited By ~ 13

Author(s):

Gianpiero Colonna ◽

Lucia D. Pietanza ◽

Giuliano D’Ammando ◽

Roberto Celiberto ◽

Mario Capitelli ◽

...

Keyword(s):

Excited States ◽

Electronically Excited States ◽

Electronically Excited ◽

Vibrational Kinetics ◽

Kinetics Of

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The role of excited states in the gas-phase photolysis of acetaldehyde

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1973.0100 ◽

1973 ◽

Vol 334 (1598) ◽

pp. 411-426 ◽

Cited By ~ 15

Keyword(s):

Triplet State ◽

Gas Phase ◽

Excited States ◽

Product Formation ◽

Vibrationally Excited ◽

Liquid Phases ◽

Radical Decomposition ◽

A Chain ◽

Low Pressures

The cis-trans isomerization of butene-2 has been used to measure the triplet state yields in the photolysis of acetaldehyde at various wavelengths between 313 and 254 nm over the temperature range 35 to 140 °C. The results, together with those derived from chemical product formation, are consistent with data from luminescence studies. Dissociation into molecular products occurs rapidly, probably by predissociation, from a non-quenchable excited state formed by absorption. The main free radical decomposition occurs from the triplet state and this, in the absence of additives, such as butene-2, is responsible for the chain decomposition. The intersystem crossing and non-quenchable processes are independent of temperature. Isopentyl radicals formed from methyl addition to butene-2 can also propagate a chain reaction for acetaldehyde decomposition. At high temperatures and low pressures, dissociation of vibrationally excited isopentyl radicals can contribute to the measured isomerization yield. This is shown by the effect of addition of inert gas. Evidence is put forward that geometrical isomerization of the olefin involves a triplet aldehyde-olefin complex that can be decomposed by collision with ground state aldehyde molecules without cis-trans rearrangement of the olefin. This conclusion is consistent with other work in the gas and liquid phases.

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