High‐temperature collisional energy transfer in highly vibrationally excited molecules II: Isotope effects in isopropyl bromide systems

Brown, Thomas J.; King, Keith D.; Gilbert, Robert G.

doi:10.1002/kin.550190906

Cited by 7 publications

(5 citation statements)

References 38 publications

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“…By fitting the falloff data, ⟨Δ E d ⟩ was assigned as 1100 ± 100 cm −1 for self-collisions by Jung et al The very low pressure pyrolysis experiments gave ⟨Δ E d ⟩ as 850 and 1300 cm −1 for C 2 H 4 and C 6 H 6 , respectively, as bath gases, which are the most similar to SF 6 and C 4 F 10 that were studied. Similar ⟨Δ E d ⟩ values were reported from studies with isopropyl bromide . In their review of 2001, Barker, Yoder, and King favored a nearly linear relationship between ⟨Δ E d ⟩ and the vibrational energy of the excited molecule.…”

Section: Computational Resultssupporting

confidence: 62%

“…Also, some early measurements may not have been in the true high pressure limit . Tsang selected isopropyl bromide as the reference reaction for his shock-tube work, and two subsequent studies have confirmed his selection of Arrhenius parameters for isopropyl bromide. , Hippler et al combined their data with published results for t -butyl bromide to provide an Arrhenius plot encompassing 9 orders of magnitude in the rate constant. Their global fit gave Arrhenius parameters for t -butyl bromide that were slightly higher than those from Tsang’s work; this report also had included Tsang’s study of C 2 H 5 Br.…”

Section: Computational Resultsmentioning

confidence: 99%

“…Similar 〈∆E d 〉 values were reported from studies with isopropyl bromide. 36 In their review of 2001, Barker, Yoder, and King 40 favored a nearly linear relationship between 〈∆E d 〉 and the vibrational energy of the excited molecule. A modest inverse dependence of 〈∆E d 〉 on temperature is usually found, although there are examples with a more pronounced inverse dependence.…”

Section: B Comparison Of Calculated and Experimental Results For C 2 ...mentioning

confidence: 99%

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Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction

et al. 2010

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The recombination reactions of CH(2)Br and CH(2)Cl radicals have been used to generate vibrationally excited CH(2)BrCH(2)Br and CH(2)BrCH(2)Cl molecules with 91 kcal mol(-1) of energy in a room-temperature bath gas. The experimental unimolecular rate constants for elimination of HBr and HCl were compared to calculated statistical rate constants to assign threshold energies of 58 kcal mol(-1) for HBr elimination from C(2)H(4)Br(2) and 58 and 60 kcal mol(-1), respectively, for HBr and HCl elimination from C(2)H(4)BrCl. The Br-Cl interchange reaction was demonstrated and characterized by studying the CH(2)BrCD(2)Cl system generated by the recombination of CH(2)Br and CD(2)Cl radicals. The interchange reaction was identified from the elimination of HBr and DCl from CH(2)ClCD(2)Br. The interchange reaction rate is much faster than the rates of either DBr or HCl elimination from CH(2)BrCD(2)Cl, and a threshold energy of congruent with43 kcal mol(-1) was assigned to the interchange reaction. The statistical rate constants were calculated from models of the transition states that were obtained from density functional theory using the B3PW91 method with the 6-31G(d',p') basis set. The model for HBr elimination was tested versus published thermal and chemical activation data for C(2)H(5)Br. A comparison of Br-Cl interchange with the Cl-F and Br-F interchange reactions in 1,2-haloalkanes is presented.

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Section: Computational Resultssupporting

confidence: 62%

Section: Computational Resultsmentioning

confidence: 99%

Section: B Comparison Of Calculated and Experimental Results For C 2 ...mentioning

confidence: 99%

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Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction

et al. 2010

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“…66 Nevertheless, other studies have suggested that deuterium substitution yields either little change in energy transfer efficiency or that it can become even more pronounced. 73,74 In the context of the energy gap law, deuterium exchange is not expected to induce a significant effect on energy transfer efficiency, as isotope substitution primarily affects the highfrequency stretching modes and only slightly changes the lowfrequency bending modes.…”

Section: Discussionmentioning

confidence: 99%

Collisional Energy Transfer from Vibrationally Excited Hydrogen Isocyanide

Wilhelm

Dai

2019

J. Phys. Chem. A

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Collisional deactivation of vibrationally excited hydrogen isocyanide (HNC) by inert gas atoms was characterized using nanosecond time-resolved Fourier transform infrared emission spectroscopy. HNC, with an average nascent internal energy of 25.9 ± 1.4 kcal mol −1 , was generated following the 193 nm photolysis of vinyl cyanide (CH 2 CHCN) and collisionally deactivated with the series of inert atomic gases: He, Ar, Kr, and Xe. Time-dependent IR emission allows simultaneous experimental observation of the ν 1 NH and ν 3 NC stretch emissions from vibrationally excited HNC. Subsequent spectral fit analysis enables direct determination of the average energy of HNC in each spectrum and therefore a measure of the average energy lost per collision, ⟨ΔE⟩, as a function of internal energy. Collisional deactivation of excited HNC is shown to be relatively efficient, exhibiting ⟨ΔE⟩ values more than an order of magnitude larger than comparably sized molecules at similar internal energies. Furthermore, the lighter inert gases are shown to be more efficient quenchers. Both observations can be qualitatively explained by the momentum gap law modeled through the repulsive force dominated vibration-to-translation energy transfer mechanism. The feasibility of efficient collisional deactivation as a contributing factor to the observed overabundance of astrophysical HNC is discussed.

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“…We have not attempted to compare the calculated values of the present work with experimental determinations of hDEi for propane systems because to the best of our knowledge, there has been no experimental study of CET in propane þ rare gas systems. '' Indirect '' studies of related systems (e.g., 2-bromopropane þ neon 47 and deuterated cyclopropane þ helium 48 ) did not direct measure CET quantities, but inferred them from pressure-dependent thermal reaction rates at elevated temperatures. These and some more recent studies using time- resolved optoacoustic spectroscopy (e.g., C 3 F 8 þ argon 26 ) reveal no information about RET.…”

Section: E Considerations Of Qualitative Versus Versus Quantitative P...mentioning

confidence: 99%

Quasiclassical trajectory calculations of collisional energy transfer in propane systems: Multiple direct-encounter hard-sphere model

Linhananta

Lim

2002

Phys. Chem. Chem. Phys.

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Quasiclassical trajectory calculations of collisional energy transfer from highly vibrationally excited propane + rare gas systems are reported. This work extends our hard-sphere model K.F. Lim, Phys. Chem. Chem. Phys., 2000, 2, 1385) to examine the variation of the internal energy during collisions with a rare bath gas. This was accomplished by recording the vibrational and rotational energy of propane after each atom-atom encounter during trajectory simulations of propane + rare gas systems. This provides detailed information of the energy flow during a collision. It was found that collisions with small number of encounters transfer energy efficiently, whereas those with many encounters do not. Detailed analyses reveal that the former collisions arise from trajectories with high initial impact parameter, whereas the latter has small initial impact parameter. The reason behind this is the dependence of collision energy transfer (CET) of large polyatomic molecules on its shape. This is connected to the well-known role of rotational energy transfer (RET) as a gateway for CET.

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High‐temperature collisional energy transfer in highly vibrationally excited molecules II: Isotope effects in isopropyl bromide systems

Cited by 7 publications

References 38 publications

Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction

Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction

Collisional Energy Transfer from Vibrationally Excited Hydrogen Isocyanide

Quasiclassical trajectory calculations of collisional energy transfer in propane systems: Multiple direct-encounter hard-sphere model

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High‐temperature collisional energy transfer in highly vibrationally excited molecules II: Isotope effects in isopropyl bromide systems

Cited by 7 publications

References 38 publications

Unimolecular Reactions of CH2BrCH2Br, CH2BrCH2Cl, and CH2BrCD2Cl: Identification of the Cl−Br Interchange Reaction

Unimolecular Reactions of CH2BrCH2Br, CH2BrCH2Cl, and CH2BrCD2Cl: Identification of the Cl−Br Interchange Reaction

Collisional Energy Transfer from Vibrationally Excited Hydrogen Isocyanide

Quasiclassical trajectory calculations of collisional energy transfer in propane systems: Multiple direct-encounter hard-sphere model

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Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction

Unimolecular Reactions of CH₂BrCH₂Br, CH₂BrCH₂Cl, and CH₂BrCD₂Cl: Identification of the Cl−Br Interchange Reaction