Kinetics of the isotope exchange reaction of 18O with NO and O2 at 298 K

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The rates of 18O isotope exchange reactions were measured at 298 K using a discharge-flow, modulated molecular beam mass spectrometer apparatus whose detection limit for NO and O was in the 109–1010 cm−3 range. The NO exchange is very fast, k1, x=(3.7±0.5)×10−11 cm3 s−1, and, assuming statistical breakdown of a long-lived complex, the rate constant for the formation of the NO°2 complex, k1, c f is (7.4±1.0)×10−11 cm3 s−1. The slower O2 exchange was measured three different ways, yielding three rate constants whose average is k2, x=(2.9±0.5)×10−12 cm3 s−1. The results are compared with earlier isotope exchange experiments and discussed in the context of measured and calculated high pressure recombination and vibrational relaxation rate constants.

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