Diode laser studies of collisional energy transfer

Flynn, George W.; Weston, Ralph E.

doi:10.1021/j100133a003

Cited by 44 publications

(38 citation statements)

References 15 publications

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“…3 Since the time of an impulsive interaction is quite short, complete energy randomization among all available degrees of freedom of the collision system is not achieved. However, the degrees of freedom of the polyatomic collider may participate to some extent in the energy transfer.…”

Section: Discussionmentioning

confidence: 99%

“…This latter result is particularly intriguing in light of recent observations that vibrationally excited O 2 molecules with V g 26 are quenched much more efficiently by O 2 colliders than O 2 with V < 26, raising the possibility that for O 2 (Vg26) the reactive channel yielding O 3 opens up. 9 In the present article, we extend our studies of the CID of NO 2 * to include the molecular colliders HCl, CO 2 , N 2 O, and NH 3 . These studies are motivated in part by recent observations by Hartland and Dai who noted that in the deactiVating collisions of NO 2 *, the average energy transferred per collision is much higher for triatomic colliders, compared with atomic and diatomic colliders.…”

Section: Introductionmentioning

confidence: 94%

“…These studies are motivated in part by recent observations by Hartland and Dai who noted that in the deactiVating collisions of NO 2 *, the average energy transferred per collision is much higher for triatomic colliders, compared with atomic and diatomic colliders. 10,11 It is also known that the quenching rates of NO 2 * by molecular colliders such as NH 3 and H 2 O are particularly high. 12,13 A second important issue concerns the influence of attractive forces and reactive pathways in collisions of highly excited molecules.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

et al. 1996

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NO 2 in high vibrational levels was prepared in a pulsed molecular beam by laser excitation of the mixed 1 2 A 1 /2 2 B 2 state to energies hν below dissociation threshold D 0 , D 0 -hν ) 0-500 cm -1 . The beam of excited molecules was crossed with pulsed, neat molecular beams of HCl, CO 2 , N 2 O, and NH 3 at relative collision energies of ∼2000 cm -1 , and the NO produced by collision-induced dissociation (CID) was detected stateselectively. The CID yield spectra obtained by monitoring specific NO rotational levels while scanning the excitation wavelength show spectral features identical with those in the fluorescence excitation spectrum of NO 2 . The yield of the CID products, however, decreases exponentially (compared with the fluorescence spectrum) with the increase of the amount of energy required to reach the threshold of appearance of the monitored NO state. The average energy transferred per activating collision with polyatomic colliders is in the range 130-200 cm -1 , having values similar to or lower than those for diatomic and atomic colliders. This is in contrast to deactivating collisions, in which polyatomic colliders are in general more effective. The results are discussed in terms of a mechanism in which the NO 2 molecules are activated by impulsive collisions creating a distribution of molecules in quantum states above D 0 whose populations diminish exponentially with energy. The collisional activation is followed by unimolecular decomposition. The differences between the activation and deactivation pathways are rationalized in terms of the number of degrees of freedom available for energy transfer in each channel.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

et al. 1996

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“…Very valuable and detailed experimental data on inelastic collisions have recently been obtained from diode laser spectroscopy of the bath gas, which allows full rotational, vibrational and translational information on the result of a single collision. [35][36][37][38][39][40][41]47 Fully state-resolved observation of the energy transfer on the acceptor side, which characterized part of the far downward wing of P(EЈ,E) ͑i.e., at a restricted range of large ⌬E values͒, have so far been possible for CO 2 as a collider. To put the measured ''partial'' P(EЈ,E) data from these measurements on an absolute scale involves a non trivial problem of suitable normalization.…”

Section: Introductionmentioning

confidence: 99%

Collisional energy transfer probabilities of highly excited molecules from kinetically controlled selective ionization (KCSI). II. The collisional relaxation of toluene: P(E′,E) and moments of energy transfer for energies up to 50 000 cm−1

Lenzer

Luther

Reihs

et al. 2000

The Journal of Chemical Physics

110

156

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Complete and detailed experimental transition probability density functions P(E′,E) have been determined for the first time for collisions between a large, highly vibrationally excited molecule, toluene, and several bath gases. This was achieved by applying the method of kinetically controlled selective ionization (KCSI) (Paper I [J. Chem. Phys. 112, 4076 (2000), preceding article]). An optimum P(E′,E) representation is recommended (monoexponential with a parametric exponent in the argument) which uses only three parameters and features a smooth behavior of all parameters for the entire set of bath gases. In helium, argon, and CO2 the P(E′,E) show relatively increased amplitudes in the wings—large energy gaps |E′−E|—which can also be represented by a biexponential form. The fractional contribution of the second exponent in these biexponentials, which is directly related to the fraction of the so-called “supercollisions,” is found to be very small (<0.1%). For larger colliders the second term disappears completely and the wings of P(E′,E) have an even smaller amplitude than that provided by a monoexponential form. At such low levels, the second exponent is therefore of practically no relevance for the overall energy relaxation rate. All optimized P(E′,E) representations show a marked linear energetic dependence of the (weak) collision parameter α1(E), which also results in an (approximately) linear dependence of 〈ΔE〉 and of the square root of 〈ΔE2〉. The energy transfer parameters presented in this study form a new benchmark class in certainty and accuracy, e.g., with only 2%–7% uncertainty for our 〈ΔE〉 data below 25 000 cm−1. They should also form a reliable testground for future trajectory calculations and theories describing collisional energy transfer of polyatomic molecules.

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“…Although HCO 2 is of minor importance for the HO + CO → H + CO 2 reaction, it might significantly impact the reactive and inelastic collisions between a fast H and CO 2 . 15,16 Thus, a better understanding of its stability and dissociation dynamics helps to provide a comprehensive picture of the HOCO system. The photodetachment of HCO 2 − and its deuterated isotopomer was first investigated by Neumark and coworkers.…”

Section: Introductionmentioning

confidence: 99%

State-Resolved Quantum Dynamics of Photodetachment of HCO₂⁻/DCO₂⁻ on an Accurate Global Potential Energy Surface

Zou

Wang

et al. 2015

J. Phys. Chem. A

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Full-dimensional quantum dynamics studies of the photodetachment of HCO2(-) and DCO2(-) are reported using a wave-packet method on an accurate global potential energy surface of the neutral HOCO/HCO2 system. The calculated photoelectron spectra reproduced both the positions and widths of the main HCO2 and DCO2 peaks observed in experiment. Specifically, both the (2)A1 and (2)B2 resonance peaks of the neutral radicals were identified in our simulations thanks to the adiabatic PES that captures both the (2)A1 and (2)B2 minima. The narrow widths and isotope effect of the lowest resonances are indicative of tunneling-facilitated predissociation. Furthermore, the dissociation product CO2 was found to be excited in both its symmetric stretching and bending modes, which are coupled via a strong Fermi resonance, but rotationally cold, in good agreement with the recent photoelectron-photodetachment coincidence experiments.

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Diode laser studies of collisional energy transfer

Cited by 44 publications

References 15 publications

Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

Collisional energy transfer probabilities of highly excited molecules from kinetically controlled selective ionization (KCSI). II. The collisional relaxation of toluene: P(E′,E) and moments of energy transfer for energies up to 50 000 cm−1

State-Resolved Quantum Dynamics of Photodetachment of HCO₂⁻/DCO₂⁻ on an Accurate Global Potential Energy Surface

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Diode laser studies of collisional energy transfer

Cited by 44 publications

References 15 publications

Molecular Beams Studies of the Dissociation of Highly Excited NO2 Induced by Molecular Colliders

Molecular Beams Studies of the Dissociation of Highly Excited NO2 Induced by Molecular Colliders

Collisional energy transfer probabilities of highly excited molecules from kinetically controlled selective ionization (KCSI). II. The collisional relaxation of toluene: P(E′,E) and moments of energy transfer for energies up to 50 000 cm−1

State-Resolved Quantum Dynamics of Photodetachment of HCO2−/DCO2− on an Accurate Global Potential Energy Surface

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Product

Resources

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Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

Molecular Beams Studies of the Dissociation of Highly Excited NO₂ Induced by Molecular Colliders

State-Resolved Quantum Dynamics of Photodetachment of HCO₂⁻/DCO₂⁻ on an Accurate Global Potential Energy Surface