Thermal decomposition of CF3Br using Br-atom absorption

✍ Scribed by J. Hranisavljevic; J. J. Carroll; M.-C. Su; J. V. Michael

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 185 KB
• Volume: 30
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1998)30:11<859::aid-kin8>3.0.co;2-u

✦ Synopsis

Br-atom atomic resonance absorption spectrometry (ARAS) has been developed and applied to measure thermal decomposition rate constants for CF Br (ϩ Kr) : CF ϩ 3 3 over the temperature range, 1222-1624 K. The Br-atom curve-of-growth Br (ϩ Kr) (145 Ͻ was determined using this reaction. For molecules cm Ϫ3 , ab-12 Ͻ 163 nm) [Br] Յ 1 ϫ 10 sorbance, [Br], yielding . The curve-of-growth Ϫ13 Ϫ14

2

(ABS) ϭ 1.410 ϫ 10 ϭ 1.419 ϫ 10 cm was then used to convert (ABS) to Br-atom profiles which were then analyzed to give measured rate constants. These can be expressed in second-order by Ϫ9 k ϭ 8.147 ϫ 10 exp(Ϫ 1 A unimolecular theoretical ap-3 Ϫ1 Ϫ1

24488 K/T ) cm molecule s (Ϯ33%, 1222 Յ T Յ 1624 K). proach was used to rationalize the data. Theory indicates that the dissociation rates are closer to second-than to first-order, i.e., the magnitudes are 30-53% of the low-pressure-limit rate constants over 1222-1624 K and 123-757 torr. With the known, 0 E ϭ ⌬H ϭ 0 0 the optimized theoretical fit to the ARAS data requires Ϫ1 70.1 kcal mole , ͗⌬E͘ ϭ down These conclusions are consistent with recently published data and theory from Ϫ1 550 cm .