Kinetic studies of the reactions NH(X{sup 3}{Sigma}{sup {minus}}) + NO and NH(X{sup 3}{Sigma}{sup {minus}}) + O{sub 2} at elevated temperatures
- Univ. Heidelberg (Germany). Physikalisch-Chemisches Institut
- Bhabha Atomic Research Centre, Bombay (India). Chemistry Division
Absolute rate coefficients for the reaction of NH(X{sup 3}{Sigma}{sup {minus}}) + NO = products (k{sub 1}) and NH(X{sup 3}{Sigma}{sup {minus}}) + O{sub 2} = products (k{sub 2}) were measured as a function of temperature in a heatable quartz reactor by means of the laser photolysis/laser-induced fluorescence (LP/LIP) pump-probe technique. NH(X{sup 3}{Sigma}{sup {minus}}) radicals were produced by the 193 nm photolysis of isocyanic acid in the presence of a large excess of xenon. The measured rate coefficients can be described by the following expressions: k{sub 1}(293 < T < 1,085 K) = 10{sup 14.18} {times} (T/298 K){sup ({minus}1.60 {+-} 0.01)} exp({minus}3.8 {+-} 0.2 kJ/mol/RT) cm{sup 3}/mol s; k{sub 2}(293 < T < 793 K) = 10{sup 9.38} {times} (T/298 K){sup (3.34 {+-} 0.15)} {times} exp(2.3 {+-} 0.4 kJ/mol/RT) cm{sup 3}/mol s. For the reaction NH(X{sup 3}{Sigma}{sup {minus}}) + NO (1), the branching ratio {beta} = k{sub 1a}/k{sub 1} into the OH product channel -- NH(X{sup 3}{Sigma}{sup {minus}}) + NO = OH + N{sub 2} (1a) -- was measured by means of a calibration method to be {beta} = (0.15 {+-} 0.05) at 300 K. In addition, the following temperature-dependent removal rate coefficient for NH(X{sup 3}{Sigma}{sup {minus}}, v = 1) by NO was measured: k{sub 1(v = 1)}(293 < T < 922 K) = 10{sup 13.68} {times} (T/298 K){sup {minus}0.71} {times} exp(0.27 {+-} 0.01 kJ/mol/RT) cm{sup 3}/mol s.
- OSTI ID:
- 93249
- Report Number(s):
- CONF-940711--
- Country of Publication:
- United States
- Language:
- English
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