Collisional energy transfer in the two-channel thermal decomposition of bromoethane-1,1,2,2-d4

Nguyen, Tam T., King, Keith D. and Gilbert, Robert G. (1983) Collisional energy transfer in the two-channel thermal decomposition of bromoethane-1,1,2,2-d4. Journal of Physical Chemistry, 87 3: 494-498. doi:10.1021/j100226a024

Author Nguyen, Tam T.
King, Keith D.
Gilbert, Robert G.
Title Collisional energy transfer in the two-channel thermal decomposition of bromoethane-1,1,2,2-d4
Journal name Journal of Physical Chemistry   Check publisher's open access policy
ISSN 0022-3654
Publication date 1983-02
Sub-type Article (original research)
DOI 10.1021/j100226a024
Volume 87
Issue 3
Start page 494
End page 498
Total pages 5
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Formatted abstract
The two-channel thermal decomposition of CHD 2CD 2Br (products HBr + C 2D 4, DBr + CHDCD 2), along with the decomposition of CH 3CH 2Br, has been studied by using the technique of very low-pressure pyrolysis (VLPP). Rate coefficients were obtained at pressures both so low that only gas/wall collisions occur (over the temperature range 950-1200 K) and dilute in various bath gases (pressures up to 10 Pa) over the range 1000-1070 K. Fitting these data by solution of the appropriate reaction-diffusion integrodifferential master equation yields the gas/wall collisional efficiency, the extrapolated high-pressure rate parameters, and the gas/gas collisional energy transfer probability function, P(E,E′). The extrapolated high-pressure rate coefficients are as follows: for CHD 2CD 2Br, 10 13.20 exp(-227.4 kJ mol -1/RT) s -1 (HBr elimination), 10 13.15 exp(-230.2 kJ mol -1/RT) s -1 (DBr elimination), and 10 13.6 exp(-221 kJ mol -1/RT) s -1 for CH 3CH 2Br, in good agreement with those obtained by other methods. Gas/wall collision efficiencies (the wall being seasoned quartz) are ∼0.6 at 1200 K, ∼0.8 at 1000 K (with those for the d 4 species ∼10% less than for the d 0), in accord with values estimated from the potential well depth. The data are moderately sensitive to P(E,E′). Assuming this for downward transitions to be a function of E - E′ alone, we found that this function falls off more steeply than exponential, as found previously for chloroethane. Average bromoethane/M downward energy transfer values (〈ΔE down〉) are 250 (M = Ne), 600 (M = CO 2), 850 (M = C 2H 4), and 1200 (M = benzene) cm -1, the variation of 〈ΔE down〉 with temperature being less than experimental uncertainty over the small experimental temperature range. © 1983 American Chemical Society.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemistry and Molecular Biosciences
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Created: Mon, 07 Mar 2011, 15:54:09 EST