التفاصيل البيبلوغرافية
| العنوان: |
Thermal rate constants for the Cl+H2 and Cl+D2 reactions between 296 and 3000 K. |
| المؤلفون: |
Kumaran, S. S., Lim, K. P., Michael, J. V. |
| المصدر: |
Journal of Chemical Physics; 12/1/1994, Vol. 101 Issue 11, p9487, 12p |
| مصطلحات موضوعية: |
PHOTOCHEMISTRY, ABSORPTION, CHEMICAL decomposition, CHEMICAL reactions, DYNAMICS |
| مستخلص: |
Rate constants for the Cl+H2 and D2 reactions have been measured at room temperature by the laser photolysis-resonance absorption (LP-RA) technique. Measurements were also performed at higher temperatures using two shock tube techniques: laser photolysis-shock tube (LP-ST) technique with Cl-atom atomic resonance absorption spectrometric (ARAS) detection, over the temperature range 699–1224 K; and higher temperature rates were obtained using both Cl-atom and H-atom ARAS techniques with the thermal decomposition of COCl2 as the Cl-atom source. The combined experimental results are expressed in three parameter form as kH2( ± 15%) = 4.78 × 10-16 T1.58 exp(-1610 K/T) and kD2( ± 20%) = 9.71 × 10-17 T1.75 exp(-2092 K/T) cm3 molecule-1 s-1 for the 296–3000 K range. The present results are compared to earlier direct studies which encompass the temperature ranges 199–1283 (H2) and 255–500 K (D2). These data including the present are then used to evaluate the rate behavior for each reaction over the entire experimental temperature range. In these evaluations the present data above 1300 K was given two times more weight than the earlier determinations.The evaluated rate constants are: kH2( ±14%)=2.52×10-11 exp(-2214 K/T) (199≤T<354 K), kH2(±17%)=1.57×10-16 T1.72 exp(-1544 K/T) (354≤T≤2939 K), and kD2(±5%)=2.77×10-16 T1.62 exp(-2162 K/T) (255≤T≤3020 K), in molecular units. The ratio then gives the experimental kinetic isotope effect, KIE ≡ (kH2/kD2). Using 11 previous models for the potential energy surface (PES), conventional transition state theoretical (CTST) calculations, with Wigner or Eckart tunneling correction, are compared to experiment. At this level of theory, the Eckart method agrees better with experiment; however, none of the previous PES’s reproduce the experimental results. The saddle point properties were then systematically varied... [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
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