Intermolecular vibrational energy transfer in thermal unimolecular systems

Tardy, D. C.; Rabinovitch, B. S.

doi:10.1021/cr60307a004

Cited by 474 publications

(240 citation statements)

References 31 publications

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“…The mathematical models usually used to interpret energy transfer data both in conventional thermal 10 and VEM 4 systems give the probability. P(AE), of a down-transition of magnitude AE by the substrate molecule as an exponential (eq.…”

Section: Resultsmentioning

confidence: 99%

Single-collision gas-surface vibrational energy transfer in a reacting system

Kelley¹,

Kasai²,

Rabinovitch³

1981

J. Phys. Chem.

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Section: Resultsmentioning

confidence: 99%

Single-collision gas-surface vibrational energy transfer in a reacting system

Kelley¹,

Kasai²,

Rabinovitch³

1981

J. Phys. Chem.

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“…A diffuse scattering model (Chen et al, 1997), which makes the assumption that each ion/helium collision is highly efficient at removing excess internal energy from the ion, was used to determine the highest cooling rates that might be expected. Alternatively, the exponential model for inefficient colliders (Tardy & Rabinovitch, 1977), which employs a relatively small energy down-step size, was used to estimate the lowest cooling rates that might be expected. For the multiple alanine-glycine (AG) polypeptide ions (Griffin & McAdoo, 1993) modeled in the study [viz., (AG) 8 Ϫ (AG) 32 ], the collisional cooling rates of 200 -2000 s Ϫ1 that were obtained with the diffuse scattering model give cooling rates about a factor of three greater than the inefficient colliders model for the same ion.…”

Section: Ion/ion Reactions Of Multiply Charged Ions ▪ Equivalent To Tmentioning

confidence: 99%

Ion/ion chemistry of high-mass multiply charged ions

McLuckey

Stephenson

1998

Mass Spectrom. Rev.

226

189

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Electrospray ionization has enabled the establishment of a new area of ion chemistry research based on the study of the reactions of high-mass multiply charged ions with ions of opposite polarity. The multiple-charging phenomenon associated with electrospray makes possible the generation of multiply charged reactant ionsthat yield charged products as a result of partial neutralization due to ion/ion chemistry. The charged products can be readily studied with mass spectrometric methods, providing useful insights into reaction mechanisms. This review presents the research done in this area, all of which has been performed within the past decade.

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“…In order to account for collisional energy transfer, the collision step size ͑den-sity͒ distribution P c (T,EЈ,E) must be incorporated in the master equation. 16,18 The collision step size distribution is the probability that a molecule which initially possessed energy in the range E to EϩdE is found in the energy range EЈ to EЈϩdEЈ after a single collision with a bath gas at temperature T. When multiplied by the collision frequency ͑assumed 19 to be due to collisions between particles which interact according to the Lennard-Jones potential͒, the collision step size distribution describes the collisional rate of production and loss of population. Unfortunately, P c (T,EЈ,E) is not known with certainty for any molecule and nothing is known about it for NB.…”

Section: Principal Assumptionsmentioning

confidence: 99%

“…Previous model studies by numerous researchers have shown that the detailed functional form of P c (T,EЈ,E) makes little difference in single-channel unimolecular reaction rate studies. [11][12][13] The conventional functional form often arbitrarily chosen for P c (T,EЈ,E) is the ''exponential model'' 19,20 …”

Section: Principal Assumptionsmentioning

confidence: 99%

“…The exponential model has been shown to give good descriptions of data from both unimolecular rate coefficient studies 19,21 and relatively ''direct'' experiments on energy transfer. 17,22,23 ''Supercollisions,'' in which surprisingly large amounts of energy are transferred per collision, 20,24,25 can be pragmatically and unambiguously defined as any deviation from the exponential model, but the reported deviations are rather small, 17,26,27 even when supercollisions are measurable.…”

Section: Eрeјрϱ ͑2b͒mentioning

confidence: 99%

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Vibrational energy transfer in shock-heated norbornene

Barker

King

1995

The Journal of Chemical Physics

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Recently, Kiefer et al. ͓J. H. Kiefer, S. S. Kumaran, and S. Sundaram, J. Chem. Phys. 99, 3531 ͑1993͔͒ studied shock-heated norbornene ͑NB͒ in krypton bath gas using the laser-schlieren technique and observed vibrational relaxation, unimolecular dissociation ͑to 1,3-cyclopentadiene and ethylene͒, and dissociation incubation times. Other workers have obtained an extensive body of high-pressure limit unimolecular reaction rate data at lower temperatures using conventional static and flow reactors. In the present work, we have developed a vibrational energy transfer-unimolecular reaction model based on steady-state RRKM calculations and time-dependent master equation calculations to satisfactorily describe all of the NB data ͑incubation times, vibrational relaxation times, and unimolecular rate coefficients͒. The results cover the temperature range from ϳ300 to 1500 K and the excitation energy range from ϳ1 000 to 18 000 cm Ϫ1 . Three different models ͑based on the exponential step-size distribution͒ for the average downward energy transferred per collision, ͗⌬E͘ down were investigated. The experimental data are too limited to enable the identification of a preferred model and it was not possible to determine whether the average ͗⌬E͘ down is temperature dependent. However, all three ͗⌬E͘ down models depend linearly on vibrational energy and it is concluded that standard unimolecular reaction rate codes must be revised to include energy-dependent microcanonical energy transfer parameters. The choice of energy transfer model affects the deduced reaction critical energy by more than 2 kcal mol Ϫ1 , however, which shows the importance of energy transfer in determining thermochemistry from unimolecular reaction fall-off data. It is shown that a single set of Arrhenius parameters gives a good fit of all the low temperature data and the shock-tube data extrapolated to the high pressure limit, obviating the need to invoke a change in reaction mechanism from concerted to diradical for high temperature conditions. Some possible future experiments are suggested.

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Intermolecular vibrational energy transfer in thermal unimolecular systems

Cited by 474 publications

References 31 publications

Single-collision gas-surface vibrational energy transfer in a reacting system

Single-collision gas-surface vibrational energy transfer in a reacting system

Ion/ion chemistry of high-mass multiply charged ions

Vibrational energy transfer in shock-heated norbornene

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