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

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.

[1]  J. Jeffries,et al.  Kinetics of the reaction of CH3O with NO2 , 1985 .

[2]  Ian W. M. Smith,et al.  Vibrational relaxations of NO by atomic oxygen , 1979 .

[3]  H. Niki,et al.  On the Exchange Reaction 16O+18O2 , 1965 .

[4]  M. Quack,et al.  Complex Formation in Reactive and Inelastic Scattering: Statistical Adiabatic Channel Model of Unimolecular Processes III , 1975 .

[5]  Frederick Kaufman.  Kinetics of elementary radical reactions in the gas phase , 1984 .

[6]  K. Bayes,et al.  Electronic Energy Transfer from 32O2(a1Δg) to 36O2(X 3Σg , 1972 .

[7]  J. Troe,et al.  High‐pressure range of the recombination O + O2 → O3 , 1984 .

[8]  J. Calo,et al.  Phase‐sensitive pulse counting in modulated beam mass spectrometry , 1974 .

[9]  J. Troe,et al.  Photolysis quantum yields and atom recombination rates of bromine in compressed gases. Experiments up to 7 kbar , 1984 .

[10]  A. Varandas,et al.  Dynamics of the 18O + 16O2(υ=0) exchange reaction on a new potential energy surface for ground-state ozone , 1982 .

[11]  M. Quack,et al.  Unimolecular Processes V: Maximum Free Energy Criterion for the High Pressure Limit of Dissociation Reactions , 1977 .

[12]  M. Quack,et al.  Vibrational Relaxation of Diatomic Molecules in Complex Forming Collisions with Reactive Atoms , 1977 .

[13]  J. Herron,et al.  Mass Spectrometric Study of the Isotopic Exchange Rate of Oxygen Atoms with O2, NO, and NO2 , 1964 .

[14]  S. Jaffe,et al.  Isotopic exchange reactions of atomic oxygen produced by the photolysis of NO2 at 3660 Å , 1966 .

[15]  D. Singleton,et al.  Evaluations of the mean values and standard errors of rate constants and their temperature coefficients , 1979 .

[16]  G. Brink.  ELECTRON BOMBARDMENT MOLECULAR BEAM DETECTOR , 1966 .

[17]  R. L. Brown.  Tubular Flow Reactors With First-Order Kinetics. , 1978, Journal of research of the National Bureau of Standards.

[18]  D. C. Tardy,et al.  Theory of Unimolecular Reactions , 1973 .

[19]  Paul J. Crutzen,et al.  Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry: Supplement I CODATA Task Group on Chemical Kinetics , 1982 .

[20]  W. Fite.  Detection of radicals and excited molecules in dynamic systems , 1975 .

[21]  J. Jeffries,et al.  Kinetics of polyatomic radical reactions using a versatile flow reactor apparatus , 1984 .