Kinetic study of the absolute rate constant for the reaction between Na + N2O in the temperature range 349–917K by time-resolved atomic resonance absorption spectroscopy at λ = 589 nm (Na(32PJ) ← Na(32S12)) following pulsed irradiation
✍ Scribed by D. Husain; P. Marshall
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- English
- Weight
- 464 KB
- Volume
- 60
- Category
- Article
- ISSN
- 0010-2180
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✦ Synopsis
We present a kinetic study of the reaction between atomic sodium and nitrous oxide in the temperature range 349-917K. Na(32S~/2) was generated by the pulsed irradiation of NaI vapor in the presence of N20 and excess helium buffer gas, and monitored photoelectrically in the "single-shot" mode by time-resolved atomic resonance absorption spectroscopy of the unresolved doublet at X = 589 nm (Na(32Pj) *--Na(3~S~2)). The photoelectric signals representing resonance absorption were amplified without distortion, captured and digitized in a transient recorder, and interfaced to a microcomputer for kinetic analysis. Absolute second-order rate constants for the reaction Na + N20~ NaO + N2
(1)
were measured at 349, 390, 473, 540, 730, and 917K, leading to the following Arrhenius form:
kl= (1.9+-0.3) × 10 -~° × exp( -12.5 +_ 0.6 kJ mol-I/RT)
This result is compared with rate constants measured at single temperatures using diffusion flames at T = ca. 535K and a fast flow reactor at T = ca. 330K where, in both cases, atomic densities of Na(32S.2) are at least a factor of 103 greater than employed in the present investigation and where the effect of secondary reactions of NaO is significant. Finally, reaction (1) is considered in terms of the potential energy surfaces involved in reaction on the basis of Cs symmetry in the "least symmetrical complex" and the weak spin orbit coupling approximation.